1992 Yamaha 115 Jet DRive won't rev up

riverview

Cadet
Joined
Aug 13, 2011
Messages
8
1992 Yamaha Jet drive two stroke will not rev above 3200 under load.

Used the boat and it ran fine, restarted it and it would not rev above 3200 RPM under load. Started it in the driveway and it revs up like it should.

KTook it to the shop and they tested compression, spark etc and said everything was fine, tore the carbs apart and set them up and it still will not rev up under load.

Anyone have any ideas or had the same problem. Hate paying $110 an hour and it still isn't fixed.

Thanks
 

Yaskeeter

Recruit
Joined
Aug 15, 2011
Messages
2
Re: 1992 Yamaha 115 Jet DRive won't rev up

I don't get why no one responds to us "Jet Guys". Guess not too many of us out there but face it, only the lower end is what's different. I have a 2000 115 Yamie on the back of my ZX18. Low hours and have had no problems yet. I work in an automotive repair shop and understand how all these systems & components work. I wouldn?t claim to be a marine expert by any means. Anyway, I've spent a lot of time at work lately researching the ethanol fuel, the marinas in my area only sell the 10% blend now & it's caused a bunch of problems in my area this year. The most interesting thing learned in my research has been the gas companies are able to use the 10% alcohol to get the octane where they need it, 87, 93 etc. I have not been able to confirm this for a fact as of yet. What was said was that as the alcohol starts separate, may only take 3-4 weeks or so, the octane settles to the bottom of the fuel tank and gets used up first. What would be left is crap fuel that nothing would run good on. This would be my bet on your problem. It would be real hard to test for this and prove short of replacing the fuel, but this is what i would try first. If you haven't done so yet get the Yamaha fuel separating filter to mount back by your fuel supply, its cheap insurance. Run the new ethanol fuel additive with every tank and remember even then the fuel is only good for 4-12 months depending on how much you dose. Wish you luck.
 

riverview

Cadet
Joined
Aug 13, 2011
Messages
8
Re: 1992 Yamaha 115 Jet DRive won't rev up

I agree, that ethanol and two strokes are not a good idea. However, here in Canada Shell has a Vpower gas that has no ethanol and that is all I use as well as Stabil marine additive. Also have a separate water separator fuel filter.

It appears that the shop I took it to made a mistake about the ignition system, makes you wonder. Under load the CDI wasn't working quite right at highter RPM and also had a bad coil.

Anyway, everything is back to normal and I am happy while being poorer.
 
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