40 hp johnno problem!

[Blaster Bretty]

G-day bloke's and chick's, I got one those 40hp johnno's, 2 stroke 2000 model, 2 cylinder, elecy start + trim etc! as of late it has been a real dog to start! now it fire's on the 3rd crank (thats about about 3 x 3second crank's) and even then will splutter and stall and then it will fire all the time but continue to stall until about the 5th or 6th time and then revs up + splutters a bit and after warming go's ok but the last 2 time's I have had her out I have had a fuel flow issue at full throttle! she will go at full throttle (6500rpm) and then after about 10 seconds seems to starve of fuel. If I keep her at about 5000rpm she will not miss a beat all day! could this be an ignition problem or maybe a choke problem because if im idleing and want to take off it seems to flood a bit then she will kick in! Im thinking maybe the carbies need a clean! I replaced the plugs + filter a few months back but what about the carbie's, could the jets in them be a bit dirty or something like that!
As I said she go's good at about 5000rpm ( could only be 4000rpm, tacho out a wee bit) but if I try to give it a good blast for an extended time at full throttle or even 3/4 ( 5500rpm) it will start to cut out!
Any advice greatly appreciated!, thanks in advance!

Bretty

[blacksunday]

mate the old man tinny was doing the same thing it was a 200o 40hp johnson as well took into the the dealer and they cleaned out the carbs now running sweet again he says.the dealer told him it would have been a mix of dirty fuel and crap in there causing the problem when trying to go full stick that it would be causing it to starve for fuel.im verry surpised to hear someone else is having the same problem.:o

[Chimo]

Bretty

Just guessing here, but what sort of fuel pump do the 40s have? I had a high revs issue with both my 115s and it turned out to be the spring on one side of the fuel pump diaphram had let go. Same issue on both OMC motors within ten hrs.

With your starting have you tried pulling the plugs out and giving them a bit of a dry and clean? Also just to check if the plugs are really good have you tried heating them with a gas torch and then trying to start.

Have had similar issues starting with a little OMC I have and if the plugs not in real good dry uncarboned state it wastes too much time till I rip it out and do the above or at least clean and dry it.

Cheers
Chimo

PS Hows the big machine going?

[Blaster Bretty]

Bretty

Just guessing here, but what sort of fuel pump do the 40s have? I had a high revs issue with both my 115s and it turned out to be the spring on one side of the fuel pump diaphram had let go. Same issue on both OMC motors within ten hrs.

With your starting have you tried pulling the plugs out and giving them a bit of a dry and clean? Also just to check if the plugs are really good have you tried heating them with a gas torch and then trying to start.

Have had similar issues starting with a little OMC I have and if the plugs not in real good dry uncarboned state it wastes too much time till I rip it out and do the above or at least clean and dry it.

Cheers
Chimo

PS Hows the big machine going?
Yeah chimo I had another bloke on nuggets forum that rekons my diaphragm may have a small crack or split in it , he said these motors use a vaccum to operate the fuel pum's and when im calling for full power it starve's it of fuel!, this could be heading in the right direction here.
However to replace this diaphragm is a full mechanic job so I may go with black sunday's choice and get a full carby clean first and see how it will go!
Thanks again guy's

Bretty

[Blaster Bretty]

Bretty



PS Hows the big machine going?
Are you refering to the tritons gearbox, I had the thing rebuilt at $2750, came in better than other quote's of $2500 - $4000 and I got a rebuilt torque converter, a brand new oil pump (which was making the noise) and they even fitted an after market oil cooler up front to help from overheating! I rekon they were a good bunch of bloke's , in the end the work was done by the bloke who done the service in the first place so I have to eat my words on that one!

Bretty

[Chimo]

Bretty

The OMC man who did mine is not that far from you at Parkwood. He has been caught on these before so he knows now. Took us a long time to find the the spring was not connected on the first one, but ten minutes for the second one. I think that even with a pin hole you would still get enogh fuel but with the spring there but just not attached; which you cannot easily see, there can be an issue.

My other option for not much happening when you try and go faster is the power pack. I had the bottom half of the unit on my 9.9 start to break down so the behaviour was not consistent, probably depended on how I smiled at it. Anyhoo Ian, the man, identified the issue and fixed it after I had stuffed around for quite a while. Fixed it so well that next time I used it we spun the bush in the prop, guess it wasn't used to having that many horses spinning it.

Cheers
Chimo