2 cylinder running in one

[dnej]

Gidday,
Have a 2 cylinder 60 hp Mariner, (made by Yamaha).Put in at Raby Bay on Sunday,started first hit, and away we went. When throttleing back to slow down, motor cut back to only one cylinder.
Fished for a few hours, went to move, started immediately but on one only.
Let it run on one for a while, then the second kicked in. Had a long run to the amity banks, then the same thing happened.

Started again, same thing,one pot only, then a great run back to Raby Bay, throttled back, then lost one again.
Got to my brothers house, put the flusher on , started her up, ran on one for about 1.5 minutes, then the second kicked in,and the motor idled beautifully for the rest of the flush. Anyone got any ideas.
David

Also bro needs to repair his prop. Who does a good job.?

[melbdan]

Sounds like your losing spark in one pot, get the engine running wait till it runs on one pot and pull the spark plug lead off one pot at a time when u pull the lead and nothing happens thats the coil that is giving u trouble maybe get it checked out by an auto ele (make sure u use pliars when pulling the lead off)

[Big_Kev]

Spark or fuel.
Swap plugs from one pot to another. Or fit new ones.
Check fuel in bowls and clean the filters.
Then to the mechanics.
Be sure to smile when pulling off the plug leads with the engine running.
At least that will let you know if it is firing well.

[NQCairns]

Hi also consider the possibility of water getting into a cylinder, pull the plugs the guilty cyl plug will be very clean. nq

[dnej]

I will change the plugs, although they have only done about 4 hours. I just realised that the plug is probably fouling up when excess fuel is fed into the pot when I throttle back. This then would stay flooded when I try to restart, and remains that way till the plug cleans up. Maybe a sticking float?
Any comments.
David

[Big_Kev]

Sticky float.
Dave you are thinking a bit to hard.
Keep it simple to start with.
If the plugs are only 4 hours old they are probably ok.
Just swap them from pot to pot and see if the problem changes with it.
Drain the fuel bowls if you can and see if any crud comes out.
Cheers Kev.

[dnej]

Thanks, I will drain the bowls.
David

[Thebuffalo]

David don't let the new plugs fool you. I don't know a lot about boat motors but I do about motorbikes. I have seen new plugs die for no apparent reason, once it was in a brand new bike only a couple of hours old. Start at the easy end my friend.

Good luck

Thebuffalo.

[propdinger]

david
for a prop repair i use solas props on the sunshine coast he has fixed alot of mine as my name suggests

hit too many thingss in the creeks ...lol

jeff

[coasty]

try the plugs by pulling them both out put them back in the plug leads and hold them on the cylinder head to see if you have any spark when you turn the motor over.
i've had plugs faulty out of the packet. wait till the ceramic blows out and pops through the engine cover

[ba229]

the buffalo is right. new plugs can be just as faulty as old ones.

and although putting the plug on the block will (may) show a spark it may not spark in the cylinder. this is because when the fuel air is compressed the spark has to be stronger to jump the gap.

if it sparks on the block but not in the cylinder it could be the coil breaking down. but before worrying about that i would change plugs.

[NQCairns]

Coasty wrote:
wait till the ceramic blows out and pops through the engine cover

Crikey!!!!!!!!!!!!!!!!!

[dnej]

I have ordered the plugs, to replace the ones in the unit. However I cant understand why one would break down, after a good long run, when I throttle back, unless that pot is flooding.
You would think a dirty plug would remain dirty, and not restart after 1.5 minutes
Regards David

[Thebuffalo]

Dnej, It's not an exact science but when it comes to fault finding especially electrical it pays to start with the simplest item and work your way on from there (not trying to tell you how to suck eggs by the way). The plugs that I was referring too in previous posts were not oiled up at all. Truth be known you probably are right with you diegnosis of the problem. Worst scenario you will have new plugs for your next service when you need them. Let us know how you go.

Thebuffalo

[dnej]

I have found out it called wet fouling. Some motors have a shut down diode, that plays up. This model does not have that diode, so we have eliminated that at least.
Couldnt get out on the weekend so have done any trials with the new plugs.
Next will be secendary coil testing, then carby floats, to see why excess fuel is flooding that pot during throttle back.
Regards David

[ba229]

just re-read this post and was wondering why you think it is a flooding problem?

is it a duel carbi? or does the one carbi and intake manifold service both cylinders (this is what i would expect)? if it is the later why is the other cylinder not flooding aswell?

my old man taught me early on in life that 99.9% of problems with motors are electrical. i've had cars,lawnmowers,motorbikes and now a boat and the old man is right.

i once put new plugs into a holden EJ that i owned and spent the next 2 weeks chasing dodgy spark plugs. 2 where working intermittantly so when i thought i found the problem plug the other would play up.

further to this. i bought some plugs for my boat yesterday. the plugs are out in the shop for you to get yourself. the sales assistant was helping me and dropped about 5 plugs on the concrete floor (still in their boxes). these plugs were put back on the shelf. one thing plugs don't like is being dropped. so some poor person may have problems in the future with these new plugs when they buy them.

[dnej]

Has twin carbies, and the one plug wet fouls on throttle back, stays wet when restarted, for about 1.5 minutes, then kicks in and runs beautifully, til throttling back again.
Regards David

[ba229]

ok sounds like a fuel thing then :-)

it will be interesting to hear what the final verdict is.

keep us informed.

regards
alex

[Big_Kev]

May be that the float level has become to high for whatever reason.
Look for a piece of foreign material under the needle and seatholding it open.
The needle is a little pointy thing which controls the fuel into the bowl and is controlled by the float.
Check the filters and see if there is any foreign matter is in them.
Cheers Kev.

[dnej]

Kev,
That is my opinion as well . I feel the flooding is caused because the fuel continues to be drawn into the crank case chamber ,( 2 stroke) instead of being shut down by the float.
I know shutting down doesnt happen immediately,in any case, so a sticking float would compound the problem.
David
PS Who is the best Yamaha mech around, for old motors?

[Big_Kev]

Wynnum Marine is my recomendation.