15hp motor died :(

[BaitThrower]

Well was ferrying the kids and sister between vic point and coochie today and on one trip back the motor died back at the ramp. Kinda just slow idled then died.

I scraped a bank near the ramp but that didnt seem to present a prob. When I went to start it, wouldnt start. Checked fuel line, seemed to be ok. Guessing it might be something electrical. Pulled out spark plugs. They seemed ok. Just doesnt want to kick over.

Any tips or things I should check first.

[wiz]

what brand yr model all helps

lanyard safety cut out not pulled off is it

[Blackened]

G'day

My little merc had a suspect switch box within warranty quite some time ago, if yours is merc/mariner, may be an issue?

Dave

[BaitThrower]

Sorry guys. 15hp Johnson, 1986 model.

Says it should eb run with 100:1 oil ration but I have been running it at 50:1.
Would this have any effect?

Also, used a different pre-mix oil today. Was using Valvoline semi-synthetic but only bottle I could get this morning was BP Hi-Tide, although that shouldnt have any effect right? The Hi-Tide was mixed with a clean load of fuel at 50:1.

Also, motor doesnt have a safety cut out lanyard ::)

[Kleyny]

if when you try and start it and the compression fells the same start with the basics.

SPARK
put a screwdriver where the plug goes put it roughly 2-5mm form the block and get someone to pull start it.(remove the spark plug) should put out a good size blue spark.
if it does then put your plug in the lead and ground that and see what the spark is doing should fire a good size spark to the threaded section if it doesnt it stuffed (this going off a normal tang type plug)
if your not getting spark could be coil, kill switch or cdi.

FUEL
try and start it with the choke on then quickly remove the plugs they should be wet. if they arent your fuel delivery may not be right.
put a bit of fuel down its throut and see if she fire then.

neil

[BaitThrower]

if when you try and start it and the compression fells the same start with the basics.

SPARK
put a screwdriver where the plug goes put it roughly 2-5mm form the block and get someone to pull start it.(remove the spark plug) should put out a good size blue spark.
if it does then put your plug in the lead and ground that and see what the spark is doing should fire a good size spark to the threaded section if it doesnt it stuffed (this going off a normal tang type plug)
if your not getting spark could be coil, kill switch or cdi.

FUEL
try and start it with the choke on then quickly remove the plugs they should be wet. if they arent your fuel delivery may not be right.
put a bit of fuel down its throut and see if she fire then.

neil

I suspected fuel first, but after a fair bit of start attempts I pulled the plugs and they were wet so looks like fuel delivery was ok.

Will check spark plugs next. They are fairly new. Only had maybe 5 hours run time, however, I am using the compatible NGK plug instead of the Champion plug the manufacturer recommends. I don't see this as being a problem as last time i took it out she ran fine. Idle has always been a little on the slow side though.

[Kleyny]

NGK is a far better plug than a champion IMO.
you may have fouled the plugs. different than what your used to.
if you kept your old plugs put them in and see what happens.
I would still check the quality ofthe spark comeing out of the coils though.

neil

[Roughasguts]

Is it still in gear?

[BaitThrower]

Hi guys. Today I put the Champion plugs back in,a nd what do you know, she started up no problem. I also did some research and apparently the champion plugs are 0.30 gap and the compatible cross referenced NGK plug are 0.40... although some sites say different things... hmm. I do prefer NGK but might just stick with Champion plugs on this motor.

Also, was boat in gear... possibly. I did move it into and out of gear a few times but I have noticed that sometimes there is a large grey area where it should be out of gear but is still in gear. The motor dfoesn't seem to have the same feature as the older suzuki I had in that if the boat was in forward or reverse gear then the mechanism to spin the flywheel would not engage. It seems this johnno engages the mechanism no matter whether it is in gear or not... Unfortunate.

Anyway going to take it out again tomorrow and hopefully it wont do the same again. I'll be stick close to shore anyway :)

[Kleyny]

at least she going again

[BaitThrower]

at least she going again

Yep. Hopefully it stays going. :P

[Noelm]

and your Motor, DOES need 50:1 not 100:1 so make sure you continue your current mixture.

[FNQCairns]

Hi guys. Today I put the Champion plugs back in,a nd what do you know, she started up no problem. I also did some research and apparently the champion plugs are 0.30 gap and the compatible cross referenced NGK plug are 0.40... although some sites say different things... hmm. I do prefer NGK but might just stick with Champion plugs on this motor.

Also, was boat in gear... possibly. I did move it into and out of gear a few times but I have noticed that sometimes there is a large grey area where it should be out of gear but is still in gear. The motor dfoesn't seem to have the same feature as the older suzuki I had in that if the boat was in forward or reverse gear then the mechanism to spin the flywheel would not engage. It seems this johnno engages the mechanism no matter whether it is in gear or not... Unfortunate.

Anyway going to take it out again tomorrow and hopefully it wont do the same again. I'll be stick close to shore anyway :)


Also the OMC engines were effectivly designed around the Champion plug they specify, history has shown with outboards that using the plug specified including the brand saves lot's of hastles -believe it or not!

World wide all true OMC gurus will also say this, if they don't then then they just talk. It's a lesson born from knowledge over thousands of outboards nothing else.

That said, it does sound like a faulty plug (if a plug fault), complete failure is just one of those things, usually NGKs in OMC engine cause wide ranging problems all noticeable but usually doesn't stop them from getting back to the ramp.

cheers fnq

[Kleyny]

Also the OMC engines were effectivly designed around the Champion plug they specify, history has shown with outboards that using the plug specified including the brand saves lot's of hastles -believe it or not!

World wide all true OMC gurus will also say this, if they don't then then they just talk. It's a lesson born from knowledge over thousands of outboards nothing else.

That said, it does sound like a faulty plug (if a plug fault), complete failure is just one of those things, usually NGKs in OMC engine cause wide ranging problems all noticeable but usually doesn't stop them from getting back to the ramp.

cheers fnq

Very interesting

neil

[BaitThrower]

Ok a bit of an update...

After starting the motor in the bucket up yesterday quite successfully on first or second pull several times after re-installing the Champion plugs, I took it out down to Cabbage Tree point today.

Got the boat in the water, managed to start the engine ok, off we went, crusiing for about 15 minutes at various speeds, idle through to WOT etc. Decided all sounds and feels good so sounded up for s apot o anchor for a bit of fishing.. Stopped motor, fished for 15 mins, nothing around. Went to start her up again. She just wouldn't kick over at all. Started paddling back to the ramp before some nice guy offered us a tow to the other side of the river. Not far. Thanks mate if you happen to be an ausfisher!

Anyway, when I got it back home I checked fuel was going through fuel lines up to the intake, then around to the fuel filter. All seems fine. No blockages, plenty of flow. It's gotta be electrical. I pulled off the spark plug wires on both ends, and at the end coming from the coils? there seemed to be a bit of a buildup of purple/brown kinda grease stuff on the connection. I think there is a fair bit of this stuff too on the connector inside the wires? Should this be there? Wondering if it just needs new spark plugs wires... Anyway I cleaned this off the connections of the various plug points but hard to get it our of the wire connectors itself.

Tried starting again but no go. Put the NGK plugs back in and it took about a dozen yanks on the cord with quite a bit of force and eventually I got it started. It ran for 30 seconds then eventually died.

Certainly seems like its not getting spark terribly easily. Harder than a bloody chainsaw to start!

Anyone know any good online guides or videos on how to check for spark or how to test the electrical path. I'm a semi-newbie at this stuff but learning fast!

[FNQCairns]

To me anyway from what you have said, I would have the aim of replacing the coil anyway, with the thought that even if it is not the problem a spare will always be handy. they are pretty cheap for outboard parts but it is still money.

Try pulling the plug, fit it back into the plug boot, place the thread/hex on a powerhead bolt away from the sparkplug hole and get someone to pull the engine over, the spark should be bright and strong.
Another idea is to heat the coil with a hairdryer until it fails under the above test -simulates the fairly common failures due to heat sink, which does sound like your problem from your explanation but still a guess none the less.

cheers fnq

[BaitThrower]

Try pulling the plug, fit it back into the plug boot, place the thread/hex on a powerhead bolt away from the sparkplug hole and get someone to pull the engine over, the spark should be bright and strong.
cheers fnq

Ok so basically pull out each spark plug, put it back in the wiring boot. The touch the hex bit of the plug (that you put the socket on to tighten?) to one of the power head bolts, and hold it there while someone else yanks on the cord... Is that right?

I'd assume fuel should be disconnected too to avoid a bomb going off? :P

[tunaticer]

Definitely sounds to me like your engine floods unpredictably at times. When you remove the plugs are they wet looking or slightly oily looking?
Check the linkage from the choke button to the butterfly it operates that the pins are in correctly and the butterfly is not flapping in the wind so to speak. If it has a pump choke assembly check all the lines are connected properly.
It could be a small amount of debris in the needle and seat letting the fuel bowl to overfill and thus flooding the motor.
It is possible also that the fuel pump cap on the side of the motor immediately before where the fuel line goes to the carby is not seating correctly too.

Jack.

[BaitThrower]

Definitely sounds to me like your engine floods unpredictably at times. When you remove the plugs are they wet looking or slightly oily looking?
Check the linkage from the choke button to the butterfly it operates that the pins are in correctly and the butterfly is not flapping in the wind so to speak. If it has a pump choke assembly check all the lines are connected properly.
It could be a small amount of debris in the needle and seat letting the fuel bowl to overfill and thus flooding the motor.
It is possible also that the fuel pump cap on the side of the motor immediately before where the fuel line goes to the carby is not seating correctly too.

Jack.

Hi mate. When i remove plugs, they are I guess wet looking, perhaps with a bit of oil too, although this is after yanking on the cord many times to get it going, so I would expect that. I havent really tried running it, then stopping, then pulling the plugs before I try crank it over again. Should they be "dry" in this instance after you stop the motor?

Linkage from choke... this seems ok. There is a spring loaded mechanism that controls this and when choke is off this appears to hold it in ok, however, the choke pull bar/lever thingy is quite loose. I wonder if I can tigthen it a little for just a little more friction. It seems fairly lose. Once I check for spark as above, I'll check this is more detail as the next thing on the list :)

re fuel pump cap... had a look at this and everything seems well seated as far as I can tell just looking at it. Probably not the best check, but will add to the list as a possibility for later :)

[BaitThrower]

Definitely sounds to me like your engine floods unpredictably at times. When you remove the plugs are they wet looking or slightly oily looking?
Check the linkage from the choke button to the butterfly it operates that the pins are in correctly and the butterfly is not flapping in the wind so to speak. If it has a pump choke assembly check all the lines are connected properly.
It could be a small amount of debris in the needle and seat letting the fuel bowl to overfill and thus flooding the motor.
It is possible also that the fuel pump cap on the side of the motor immediately before where the fuel line goes to the carby is not seating correctly too.

Jack.

Hi mate. When i remove plugs, they are I guess wet looking, perhaps with a bit of oil too, although this is after yanking on the cord many times to get it going, so I would expect that. I havent really tried running it, then stopping, then pulling the plugs before I try crank it over again. Should they be "dry" in this instance after you stop the motor?

Linkage from choke... this seems ok. There is a spring loaded mechanism that controls this and when choke is off this appears to hold it in ok, however, the choke pull bar/lever thingy is quite loose. I wonder if I can tigthen it a little for just a little more friction. It seems fairly lose. Once I check for spark as above, I'll check this is more detail as the next thing on the list :)

re fuel pump cap... had a look at this and everything seems well seated as far as I can tell just looking at it. Probably not the best check, but will add to the list as a possibility for later :)

[BaitThrower]

and your Motor, DOES need 50:1 not 100:1 so make sure you continue your current mixture.

Yep have done 50:1 since getting :)

[Angla]

If you can have it in a darkened area and you pull the starter. Sparks will be seen jumping from the leads to the frame of the motor if they are bad anywhere.

Chris

[jimbo 69]

I've got a johno 15 96 model, not long after i bought it it started to play up.

running rough and missing on occasions and other times running ok, i stripped and cleaned the carby many times, and it would sometimes come good.

when i had had enough and realised that it was to intermitant i took it to the local johno mech, turned out to be the black box (ignition?) now it runs like a champion

he said sometimes a quick tap with a spanner can make it come good for a while and comfirm the problem

cost $290 for a new one.

[BaitThrower]

Checked spark plugs. Only getting kind of an orange coloured spark out of them. Only a slight blue if I really yank on the cord hard??

I also checked the resistance of the spark plug leads using a procedure I got off the net somewhere. Apparently set the multimeter to 40k Ohm setting, attach red pin inside plug wire, black to ground, check reading. Supposed to be anywhere between 3 and 15 ohms, with lower being better. Anyway my cheap ass multimeter doesnt have a 40 setting, only a 20k setting, and on this setting I am getting readings of 0.25 on both leads. Can anyone tell me what this figures translates to in Ohms? Thanks.

I'll probably grab some new coils, because according to you guys, I should be at least getting a decent size blue spark yeah?

[FNQCairns]

Checked spark plugs. Only getting kind of an orange coloured spark out of them. Only a slight blue if I really yank on the cord hard??

I also checked the resistance of the spark plug leads using a procedure I got off the net somewhere. Apparently set the multimeter to 40k Ohm setting, attach red pin inside plug wire, black to ground, check reading. Supposed to be anywhere between 3 and 15 ohms, with lower being better. Anyway my cheap ass multimeter doesnt have a 40 setting, only a 20k setting, and on this setting I am getting readings of 0.25 on both leads. Can anyone tell me what this figures translates to in Ohms? Thanks.

I'll probably grab some new coils, because according to you guys, I should be at least getting a decent size blue spark yeah?

Blue spark not needed, but strong and bright which you have, pull starting cannot reproduce what the engine does when running.

The aim is to give you the chance to troubleshoot in real time, your ohms seem ok to me, these are not car leads and are for all intents just copper wire like welders leads, so on average anything but a break/bad contact will be good enough, of coarse there is also optimum.

If you do have a heat related failure on one coil (not uncommon with age or a past overheat) you can now check for lack of spark easily even when on the water.

If you have one cyl failing from a coil problem while under power the other cylinder will try to do all of the work but it cannot, this is easily recognisable as the engine will run down with some fuss. If you were getting a complete spark out ie a problem further upstream of the of the coils then the engine will just cut out at speed.

The idea of flooding sounds plausible after you experience a problem, the ONLY way to start when flooded is at full throttle be sure to catch it quick though and certainly never do it in gear.

Try running the engine on muffs with the hair dryer on the suspect coil if you have one, if the problem occurs then do the spark test. You can also do this to the CDI unit.
Running the engine at night is as mentioned above a great way to spot light shows.

cheers fnq

[BaitThrower]

Blue spark not needed, but strong and bright which you have, pull starting cannot reproduce what the engine does when running.

The aim is to give you the chance to troubleshoot in real time, your ohms seem ok to me, these are not car leads and are for all intents just copper wire like welders leads, so on average anything but a break/bad contact will be good enough, of coarse there is also optimum.

If you do have a heat related failure on one coil (not uncommon with age or a past overheat) you can now check for lack of spark easily even when on the water.

If you have one cyl failing from a coil problem while under power the other cylinder will try to do all of the work but it cannot, this is easily recognisable as the engine will run down with some fuss. If you were getting a complete spark out ie a problem further upstream of the of the coils then the engine will just cut out at speed.

The idea of flooding sounds plausible after you experience a problem, the ONLY way to start when flooded is at full throttle be sure to catch it quick though and certainly never do it in gear.

Try running the engine on muffs with the hair dryer on the suspect coil if you have one, if the problem occurs then do the spark test. You can also do this to the CDI unit.
Running the engine at night is as mentioned above a great way to spot light shows.

cheers fnq

Ok on spark. Seems to be normal then by what you say when cold.

What you have said about one cylinder failing when under way, this does not seem to be the case, as everything seems to run just fine until I stop the motor for a bit of fishing, then it just doesnt restart. So that rules this one out (which is good!).

The flooding could well indeed be the cause. What are some of the possible causes of this? I've checked the choke lever and linkage and I dont think it moves anywhere when underway. Whats next to check... the carb float valve? Suggestions please :)

I'll try get the engine going on muffs (can it be in a bucket though? this is how i run the motor normally at home). So for this test, what you are saying is start the engine - if i can - let it run, pop the lid then start blasting one of the coil cases with hot air from the hair dryer yes until it fails? Which would then be indicated by a loss of one cylinder which would cause the motor to run poorly and possibly cut out? yes? Then repeat for the other coil. Is that how you do it? How long roughly should it take to heat the coils up enough to check for failure... 30 secs? 5 mins? Sorry about all the questions, just making sure I do the tests right for an accurate result.

If nothing else, I am learning a hell of a lot out of all this about the engine components and how they all work together :)

Keep the suggestions flowing!
8-)

[BaitThrower]

Since yesterday I have done some more checking with the multimeter. Coil resistance all appears to be ok, as does all the electrics etc.

Have since learnt that the spark plug gap should really be 0.30 but this Clymer workshop manual I have says 0.40 which is incorrect. Wondering if that after I have run it and it has heated up, whether the gap is expanding/widening slightly beyond 0.40" and this is what is giving me problems? i.e. harder to get a good spark when hot? I have now re-gapped the plugs to 0.30" and they seem to be sparking betetr now with a blue spark, as opposed to the light orange spark I was getting...

Also, last couple trips out, a lot of spray has come over the sides (short side dinghy) and it collects on top fo fuel tank cap which is where the breather is located. I'd guess that some of this water has found its way down the breather screw threads and into the fuel. Probably not a lot, but nonetheless, I should probably clear it... Use some Fuel Doctor to disperse this water?

[BaitThrower]

Just adding a little more to the thread for future reference of others with similar issues...

Got the engine running in the bucket today no problems. Took a few pulls to start but ok. The spark is much brighter and stronger it seems after re-gapping the plugs down to 0.30". Prior to this, the spark plugs seemed to blacken up quite a bit and I noticed the water in the bucket was rather oily and filthy after it all settled for a few hours... Seemed like there wasn't full combustion taking place in the cylinders and a lot of oil/gas being exhausted out through the prop.

After re-gapping the plugs, starting seems easier. Also, pulled the plugs and they have a nice normal tan colour and no fouling as yet. Obviously a few more tests but previously I pulled brand new plugs at 0.40" after 20 minutes of run time and they are semi-black...

Still need to do an on-water test where i get the motor really warmed up, but the spark plug gap issue, and resolution... looks to be at least a good step forward to fixing the problem, or avoiding future issues...

So, morale of the story... found out exactly what spark plug gap your motor should use, and be aware that these recommendations can change over time. Apparently Johnson recommended 0.40" with these engines, but later advised reducing to 0.30". Setting them in the lower gap range makes sense because as the plugs heat up and wear, the gap actually gets larger, and too large a gap may not produce a good enough spark for good, constant ignition. Also, while most plugs come pre-gapped these days, it is worth checking them out of the box just in case!

I may add more as I learn more :)

[choppa]

i'll be watching this thread with interest,,, same drama's are happening with my 15 hp johnno,,,,,

had it in the shop as was advised that a small screw had come adrift inside the carby,,, once this was replaced all was well,,, until last trip out when the same problem reoccured

as per baithrowers experience,, but a bit different,,, mine starts easily,,, goes well,, but when you either idle down or turn it off,,,, it struggles to restart,,, and once it fires,, its like as if its running under full choke,,, with bugger all power going to the prop,,and i have drama trying to get it to run after you throw it in gear,,,(stalls75% of the time)

one thing that did happen tho on the last trip,,, after it fired,,, and got underway,,,, i had nothing in the way of throttle,,,, this lasted for about half a kilometre,,, then a small noise from the motor,,, and full throttle resumed,,,, running it back to the marina,, it didnt miss a beat,,,until i backed off to go into the marina itself,,, and then once more,,,no power

i pulled the cowling of at home and noticed a very slight burr on the flywheel cog,,, and also on the main starter cog,,,,

wondering if the problem has anything to do with the cog not releasing after start up,,,,, i'll find out tomorrow,,,, planning to take it for a run with the toolbox on board,,,,,

2 things will happen,,,,, new motor (s) is one,,,,,,,,

choppa

[FNQCairns]

Just adding a little more to the thread for future reference of others with similar issues...

Got the engine running in the bucket today no problems. Took a few pulls to start but ok. The spark is much brighter and stronger it seems after re-gapping the plugs down to 0.30". Prior to this, the spark plugs seemed to blacken up quite a bit and I noticed the water in the bucket was rather oily and filthy after it all settled for a few hours... Seemed like there wasn't full combustion taking place in the cylinders and a lot of oil/gas being exhausted out through the prop.

After re-gapping the plugs, starting seems easier. Also, pulled the plugs and they have a nice normal tan colour and no fouling as yet. Obviously a few more tests but previously I pulled brand new plugs at 0.40" after 20 minutes of run time and they are semi-black...

Still need to do an on-water test where i get the motor really warmed up, but the spark plug gap issue, and resolution... looks to be at least a good step forward to fixing the problem, or avoiding future issues...

So, morale of the story... found out exactly what spark plug gap your motor should use, and be aware that these recommendations can change over time. Apparently Johnson recommended 0.40" with these engines, but later advised reducing to 0.30". Setting them in the lower gap range makes sense because as the plugs heat up and wear, the gap actually gets larger, and too large a gap may not produce a good enough spark for good, constant ignition. Also, while most plugs come pre-gapped these days, it is worth checking them out of the box just in case!

I may add more as I learn more :)

Missed this post, so your problem is a hot start one, think you are on the right track withthe plug gap, gapped on the smaller side will help starting and gapped tothe larger side will help burn at higher revs, many gap just a little smaller to help with wear over time as you say but not strictly needed if basic maintenace is followed as our rec engines do not see huge hours in any year.

Just don't forget for a hard to start engine that is hot/flooded, full throttle is the go, with experience in the quirkier side of your particular engine you may find the procedure where it becomes a reliable starter. Failing that your next journey will be to set the carb back to spec IMO don't go there until you have no other good choice.

good luck

cheers fnq .

[FNQCairns]

i'll be watching this thread with interest,,, same drama's are happening with my 15 hp johnno,,,,,

had it in the shop as was advised that a small screw had come adrift inside the carby,,, once this was replaced all was well,,, until last trip out when the same problem reoccured

as per baithrowers experience,, but a bit different,,, mine starts easily,,, goes well,, but when you either idle down or turn it off,,,, it struggles to restart,,, and once it fires,, its like as if its running under full choke,,, with bugger all power going to the prop,,and i have drama trying to get it to run after you throw it in gear,,,(stalls75% of the time)

one thing that did happen tho on the last trip,,, after it fired,,, and got underway,,,, i had nothing in the way of throttle,,,, this lasted for about half a kilometre,,, then a small noise from the motor,,, and full throttle resumed,,,, running it back to the marina,, it didnt miss a beat,,,until i backed off to go into the marina itself,,, and then once more,,,no power

i pulled the cowling of at home and noticed a very slight burr on the flywheel cog,,, and also on the main starter cog,,,,

wondering if the problem has anything to do with the cog not releasing after start up,,,,, i'll find out tomorrow,,,, planning to take it for a run with the toolbox on board,,,,,

2 things will happen,,,,, new motor (s) is one,,,,,,,,

choppa

Choppa try pulling the choke on to varying degrees when the engine is playing up, if it speeds up at this time then there is a metered fuel delivery problem - clean jets/bowl etc.

I have also had a little luck at full throttle traveling full speed pulling the choke fully on but keeping the throttle pegged (cannot do any specific damage), this dumps a lot of fuel and vacume through the engine and can clear minor problems - got to the stage of doing this in a maintenance sense to one particular engine which helped it behave for the entire trip more times than not as a result althought I never worked out specifically why it helped this engine through the day.

Anyway interested to hear if a little extra fuel does help the engine accelerate.

cheers fnq

[choppa]

nahhh,,, it does bugger all mate,,,, tried it in case it was a choke vibrating ""on"" whilst under way,,,

to explain a bit more in detail,,, when the motors off,,, you only have a small amount of ""play"" on the throttle to use,,, this then ""free's"" up when motor is running to allow gear to be engaged and vvvrrrooooommmmm to happen,,,,,

my problem is the motor wont allow the throttle to ""open"",,, and hence the initial stalling is caused by the revs being to low,,,

i have looked at the idle adjustment,,,looked at the mix adjustment ,,, looked at just about everything,,,, its all seems to be ok,,,

and its spasmodic,,,, meaning that you may stop n start a dozen times,,,,, then it kicks in and wants to chug along

the weekend of the m&g,,, (after coming out of the shop),,, it didn't happen at all,,, last week i moved around 2 or 3 times and went for a final run up to parrot island in the passage,,,, and bingo,,,,, a very slow start back to the ramp,,, and then it went bang,,,and kicked in,,,,

i'm fortunante,,,, that its only hanging onto the transom by the securing bolts,,,,, bugger or else to undo to make it accidentally become a reef,,,,

choppa

[BaitThrower]

Missed this post, so your problem is a hot start one, think you are on the right track withthe plug gap, gapped on the smaller side will help starting and gapped tothe larger side will help burn at higher revs, many gap just a little smaller to help with wear over time as you say but not strictly needed if basic maintenace is followed as our rec engines do not see huge hours in any year.

Just don't forget for a hard to start engine that is hot/flooded, full throttle is the go, with experience in the quirkier side of your particular engine you may find the procedure where it becomes a reliable starter. Failing that your next journey will be to set the carb back to spec IMO don't go there until you have no other good choice.

good luck

cheers fnq .

Thanks for info. Yeash I think the re-gapping has helped quite a bit. No problem at all starting and stopping and restarting in the bin at home... Although it probably doesnt get hot enough to replicate the problem in the same way as when on the water. As a side note, I did find a slightly different start procedure. This was, once engine had been run and was still warm, do a half-hearted pull on the rope, so it doesn't really have enough oomph to start, then on second pull, it seems to free up the pistons and less force needed to turn it over (is this the same kinda result as using a decompression button on a chainsaw?). Anyway, also when restarting, I have throttle at idle now, so as to not flood the engine if I hold it at full open and rope it a few times with no result.

But again, this is all very good and well at home in the bucket. The test will be whether this process works the same out on the water after I have been cruising around for a bit and the motor is much warmer.

Additionally, I have ordered ndew coils and a power pack from the USA. I don't really think it needs them. I doubt they are the problem, but no harm in putting brand new ones in anyway right? :P

[FNQCairns]

Thanks for info. Yeash I think the re-gapping has helped quite a bit. No problem at all starting and stopping and restarting in the bin at home... Although it probably doesnt get hot enough to replicate the problem in the same way as when on the water. As a side note, I did find a slightly different start procedure. This was, once engine had been run and was still warm, do a half-hearted pull on the rope, so it doesn't really have enough oomph to start, then on second pull, it seems to free up the pistons and less force needed to turn it over (is this the same kinda result as using a decompression button on a chainsaw?). Anyway, also when restarting, I have throttle at idle now, so as to not flood the engine if I hold it at full open and rope it a few times with no result.

But again, this is all very good and well at home in the bucket. The test will be whether this process works the same out on the water after I have been cruising around for a bit and the motor is much warmer.

Additionally, I have ordered ndew coils and a power pack from the USA. I don't really think it needs them. I doubt they are the problem, but no harm in putting brand new ones in anyway right? :P

Sounds like you starting to get the feel of the temperamental old girl.

Just a note on the full throttle start thing, although it goes a little against common sense, in practice in starting this procedure is less prone to flooding the engine than any other throttle position. Full throttle means less vacume=more air=less fuel=easier hot starting esp if hot start flooding is an issue.

You engine has less backpressure on the muffs this also equates to a slightly leaner start condition than if it were in water. If you replicate this slightly leaner setting on the water with the throttle when hot it may help.

cheers fnq

[FNQCairns]

nahhh,,, it does bugger all mate,,,, tried it in case it was a choke vibrating ""on"" whilst under way,,,

to explain a bit more in detail,,, when the motors off,,, you only have a small amount of ""play"" on the throttle to use,,, this then ""free's"" up when motor is running to allow gear to be engaged and vvvrrrooooommmmm to happen,,,,,

my problem is the motor wont allow the throttle to ""open"",,, and hence the initial stalling is caused by the revs being to low,,,

i have looked at the idle adjustment,,,looked at the mix adjustment ,,, looked at just about everything,,,, its all seems to be ok,,,

and its spasmodic,,,, meaning that you may stop n start a dozen times,,,,, then it kicks in and wants to chug along

the weekend of the m&g,,, (after coming out of the shop),,, it didn't happen at all,,, last week i moved around 2 or 3 times and went for a final run up to parrot island in the passage,,,, and bingo,,,,, a very slow start back to the ramp,,, and then it went bang,,,and kicked in,,,,

i'm fortunante,,,, that its only hanging onto the transom by the securing bolts,,,,, bugger or else to undo to make it accidentally become a reef,,,,

choppa

OK so is your engine young enough to have the start in gear throttle lockout gismo fitted to the engine linkages? Sounds on the surface it is sticky somehow. This device dis-allows the full range of throttle to be used unless in gear BUT pullstart is locked out unless in neutral, which is not your issue although it give the average bloke no hope when on the water with a problematic motor. Right pain in the butox from a seaworthy point of view.

cheers fnq

[BaitThrower]

My johhno lockout mechanism doesn't seem to work... I can yank on the cord all day if its in gear... I gotta look at fixing that :) Thnaks foer the info on throttle settings. I have the motor in the bin outside at the moment and testing it some more. Will test starting with full throttle. See if it floods. Although I'm starting to suspect more and more that the spark plug gapping was the problem right from the start :)

[FNQCairns]

My johhno lockout mechanism doesn't seem to work... I can yank on the cord all day if its in gear... I gotta look at fixing that :) Thnaks foer the info on throttle settings. I have the motor in the bin outside at the moment and testing it some more. Will test starting with full throttle. See if it floods. Although I'm starting to suspect more and more that the spark plug gapping was the problem right from the start :)

yeah good luck with it, in theory the bigger the SP gap but still within specs you can obtain the better the engine will perform, less fouling, less fuel used more performance etc. But as you know starting can become an issue with the bigger gaps as can motor smoothness at trolling speeds.

Very hard to replicate your on the water situations at home almost to the point of do it for interest but do not expect any quality crossover to on the water behavior.
Cold burn in neutral and the resultant carbon and free unburnt 2 stroke oil frustrate the situation greatly.

cheers fnq

[BaitThrower]

yeah good luck with it, in theory the bigger the SP gap but still within specs you can obtain the better the engine will perform, less fouling, less fuel used more performance etc. But as you know starting can become an issue with the bigger gaps as can motor smoothness at trolling speeds.

Very hard to replicate your on the water situations at home almost to the point of do it for interest but do not expect any quality crossover to on the water behavior.
Cold burn in neutral and the resultant carbon and free unburnt 2 stroke oil frustrate the situation greatly.

cheers fnq

Update.. testing in bucket at home... Full throttle restart... No problems.
SP gap... well I put back in some new NGK plugs regapped to 0.30". I noted what you said re using Champions, but havent got a spare set here... hard to get! so I wanted to test for plug fouling with this new gap setting so I used new NGK. From what i have read, the NGK equivalent should be equal to, if not better than the Champion plugs. All specs check out as same etc.

Anyway gave it a run in the bucket for a while... couple small rev cycles and trolling it at idle in the bucket for a while. Switched off, pulled the plugs and no fouling whatsoever... plugs were essentially dry... no black spots, if anything, slightest brown/tan color, but this even rubbed off so nothing permanent. They still looked new. I seem to recall last time I put in new NGK plugs at 0.40" gap setting, they came out a bit black looking even after first 10 min run in bucket. so this is definitely different.

As an aside, when I had these probs on water, it hapopened with both a set of NGK plugs the first time, and then with Champions the next. Both were set at 0.40". Anyway, still comes down to an on-water test to see if it isd indeed a gap issue, but the cleanliness of the plugs gapped at 0.30" (no fouling) vs 0.40" (quick fouling) seems to be a very good step forward at least.

Just need to find time to get on the bloody water now!
:P

[BaitThrower]

Adding more info for future reference of other Johnno 15hp 80's models owners.

Discovered today that at the end of the tiller arm is an idle adjustment. No wonder I couldn't find this mentioned in any service manuals. I spent hours looking in books but none of them mentioned it. Anyway the twist knob on the front of the tiller arm (surrounding the "STOP" button) will adjust idle revs higher/lower depending on which way it is turned. As the motor seemed to always idle a little on the lower side, I twisted it in a turn or two and now the motor purrs like a kitten at idle.

Also, I have since decarbonized the carbs and combustion chamber using OMC Engine Tuner Spray which seems to have improved running a little as well, althought his is hard to tell. Using NGK plugs gapped at 0.30 now which is working well and almost no sign of fouling so far, even after lots of idling in the bucket at home testing.

Installed new SOLAS 3-blade prop as old prop bushing had worn unevenly somewhere as propr was spinning a little out of round. Have two new ignition coils and a power pack (if needed) coming from the USA. Will install these if I again have trouble out on the water (still havent got it on water again for high speed testing, and more importantly, the restart on warm engine). Heck, I might just installt he new ones anyway and keep the older ones as backups if needed.

[BaitThrower]

Ok folks, probably the final update. yesterday finally got her out on the water...
A few stop/starts of varying time intervals and total travel of around 25km on the southport broadwater... A fair bit of idling and low speed, but a bit of near WOT (probably 80%) for a third of the distance travelled too.

New ignition coils and power pack installed.

No problem with motor idling steadily now (because I found the idle adjustment LOL) and the motor ran smoothly with little vibration. After stopping and tilting etc and leaving for about 30 mins on one occassion, she started up fine. One time a few extra pulls and half a choke to get it kicking over, but this is not un-normal for a Johnson of this era - fuel sometimes takes a while to get to chamber it seems).

Anyway all good and brought her back home. Pulled the plugs to have a look. Bottom chamber looked ok. Top was fouled a little and a touch black. This may have been because this was the first time I had run it at anything faster than fast idle since I used the Engine Tuner De-carb treatment, so hopefully this one cylinder was just blowing more of the crap off than in the other.

I re-checked compression again on both cylinders and one was 108 PSI, and the other about 105 PSI so all good there.

So what could the problem have been? Well, if you have been following along the other posts, probably the large 0.40" spark plug gap had something to do with it and may have been the major factor in this case. Fuel flow could also play a part at some stage as these motors take quite a bit of priming and a few pulls to get the fuel flowing where it needs to go, but once this is done, it flows no problem.

So until something else happens (hopefully it doesnt) I'm going to put my money on spark quality (or lack of it) over fuel (or anything else at this time).

[mr_boats]

Hi everyone

I'm actually a marine Mechanic and have been trading for over 17 years.
The first thing I do if this is booked into my shop is:
Spark and compression test. The compressin is the most important thing. If its there you have a good chance to fix the motor. As for spark. It has to be a Strong BLUE spark. You mentioned the spark was orange. This indicates WATER has fouled the plugs. If this is the case get rid of the plugs your wasting your time cleaning them and resetting them (They will just die after a little bit of running which it seems to have done) for the price of around $6 a plug replace them. But DON'T use your engine as they will just foul again and damage your new plugs. Get someone to strip the carby and clean it(Preferable a marine mechanic). Remember to clean out all fuel lines as well so if there is any water in the lines it won't go straight back into your clean carrby. Get rid of all the fuel in your tank. Clean it spotless with a cup of new fuel and a clean rag on a stick. Then you'll be right to go.
Remember the basic's of a outboard it needs 3 things to run Compression, fuel and spark. If all of these 3 things are coreect she'll run.

Cheers
Garry.

[BaitThrower]

Garry,

Thanks for the info. The water idea is new to me. Good info. I think I have it sorted now though. Compression seems good at 110 and 108 respectively. Getting a nice bright blue spark too now. Last time out the motor worked well and no sign of restart issues. If it happens again I'll investigate the water/carb issue more.

Some of the problem may have been that when sitting idle and rocking in the swell, it seems fuel somehow drains from the lines internally and when I go to start it, its getting no fuel. When trying to crank over with no choke, still no fuel flow. So I add choke (something I wasn't doing when I had the problems for fear of flooding it) and it kicks again as fuel is again re-introduced into the chambers. Note that I don't have to keep choke on once this is done again. Kick it over and it fires a little, then choke off again and she starts next pull and away we go with no further issues. I think this model uses a vacuum type pump? Not sure, but seems the vacuum is lost quite quickly when motor off?

As mentioned above, could have been many factors, but I think I have it sorted now. Compressions good, spark now good, and worked out the fuel supply anomalies that seem present in this motor. I am getting a new fuel pump shipped to change that as well to rule out that problem... if that will remedy the vacuum issue? Not sure but got it for next to nothing so no harm putting new one in I guess.

I was using new plugs at various stages. Also ran some de-carb through and now use Fuel-Doctor additive to disperse any water in the fuel. Seems to be working well.

As an aside, I ran some fuel doctor in the Lancer last tank full (motor has done 230,000km and was getting only about 380km to a tank). Adding first dose of fuel doctor and last tank got closer to 480km, although about 150km of that was highway driving. Still, seems to be getting more Kms... Fuel Doctor probably has helped clean the injectors and lines a little. I'm sold on it anyway for now. Will see how many kms it does around town on next tank load :)

[choppa]

just as a ""hopefully this will help""" comment,,,

after similar dramas with my 15hp johnno as stated in a prior response,,, it went of to the mechanics which found a small screw in the carbie set up somewhere had "created" the problem,,,,

this fixed,,, its back on the water,,,, and disdnt miss a beat for 2-3 trips out,,,

then 2 weeks ago,,, bang,, it started again,,,, runs beautifully one minute,,, then coughs splutters and seems to be running on full choke the next,,,, no power

this time i pulled the cowling off,,, deciding whether its time to create a reef

soon as the cowling came off.... no problem,,,,,,, its back to as new again

put cowling back on,,,,,,, drama reoccured,,, and this happened 99% of the time each time i took cowling off and put it back on

so,,,, (HOPEFULLY),,, a 10 cent part fixed it,,,,

cable tied the bloody sparky leads away from the cowling hook catch,,,,,,,,,,,,,

now i'm not saying this is the problem in your case,,,,,, but it seems to have fixed mine,,,,

or for the time being anyways,,,,,,,

choppa

[FNQCairns]

just as a ""hopefully this will help""" comment,,,

after similar dramas with my 15hp johnno as stated in a prior response,,, it went of to the mechanics which found a small screw in the carbie set up somewhere had "created" the problem,,,,

this fixed,,, its back on the water,,,, and disdnt miss a beat for 2-3 trips out,,,

then 2 weeks ago,,, bang,, it started again,,,, runs beautifully one minute,,, then coughs splutters and seems to be running on full choke the next,,,, no power

this time i pulled the cowling off,,, deciding whether its time to create a reef

soon as the cowling came off.... no problem,,,,,,, its back to as new again

put cowling back on,,,,,,, drama reoccured,,, and this happened 99% of the time each time i took cowling off and put it back on

so,,,, (HOPEFULLY),,, a 10 cent part fixed it,,,,

cable tied the bloody sparky leads away from the cowling hook catch,,,,,,,,,,,,,

now i'm not saying this is the problem in your case,,,,,, but it seems to have fixed mine,,,,

or for the time being anyways,,,,,,,

choppa

Ha! isn't that sometimes the way! so much for the screw theory though...

cheers fnq