97 GT-40 EFI 585 Hours / Idle up and down then stalls...

[ricofrancois]

Hi Guys

My 97 Nautique with GT-40 EFI was just serviced but one of the ongoing issue remains.

The boat always starts perfectly from cold even if not used for a couple of weeks.

The only issue is when we take a longer break between sets like 20-30min, the boat starts then on idle or in gear, the engine will rev up and down then stalls or sometimes will start then stall.

If I put more gas on idle it clears the issue and everything is fine.

If we only break 5min between sets, it doesn't happen either.

The engine runs great for anything else otherwise.

I am waiting for my mechanic to look into it but I though I would throw the ball in the meantime.

Thanks

[east tx skier]

When you take a break, try running the blower and lifting up the motorbox a bit. It almost sounds like vapor lock symptoms, but the FCC supposedly solves that. I used to have a heat sensitive MC that would act similarly with that old garbage 4010 carb.

[ricofrancois]

Someone told me it could be leaking injectors. This would explain the boat starting fine from cold or after just a short break. If the injectors are leaking for 20 minutes this could then cause the engine to run too rich. After accelerating on idle the gas clears and the boat is fine... Does it make sense?

[gtxragtop]

Someone told me it could be leaking injectors. This would explain the boat starting fine from cold or after just a short break. If the injectors are leaking for 20 minutes this could then cause the engine to run too rich. After accelerating on idle the gas clears and the boat is fine... Does it make sense?

go to autozone. rent a fuel injection pressure gauge. When engine is running check for proper pressure. Shut engine off, does pressure drop over time? If yes could be an injector leak. If this is the case, then when you will find that full throttle will allow the engine to start more quickly. The engine in this case will also likely belch black smoke (rich fuel/air ratio until the excess fuel is burned off.

[Chexi]

Search under my name. I had an idle / stallin problem. There is a link to a video that shows what happened. In my case, changing the distributor is what finally solved the problem. I believe it was probably just the pip in the distributor, but after tryin so many other things, I just wanted it fixed, so we changed the whole thing. Ran flawlessly after that.

[gtxragtop]

Search under my name. I had an idle / stallin problem. There is a link to a video that shows what happened. In my case, changing the distributor is what finally solved the problem. I believe it was probably just the pip in the distributor, but after tryin so many other things, I just wanted it fixed, so we changed the whole thing. Ran flawlessly after that.

Due to this statement " If I put more gas on idle it clears the issue and everything is fine." I do not think it would be a distributor related issue. I would think that if a distributor issue, engine RPM would be a don't care.