93 Sunsport High Idle After Cruise

[Straitcountry86]

Hey guys, just picked up a 93 Sunsport and so far it's a great boat. Only issue I'm currently having is after cruising for a little while at fairly high rpm, upon returning back to neutral the idle will sometimes stick high at about 2k rpm and sometimes even 3k rpm. The only way to return the idle to normal is to turn the key off and restart the boat, which cures the issue every time. Thus I am leaning toward it not being a cable issue. Probably something with the carb. I checked the secondary butterflies and they are not sticking open. I also cleaned and lubed the cable linkage to no avail.

Engine is a PCM 351 HO. Any thoughts?

[Straitcountry86]

Anyone????

[Jetlink]

Mine sometimes idles higher than where I would like after I do a run that requires the secondaries to open up. I usually pull it to neutral, disengage the transmission and bump the throttle real quick and it settles down at the lower idle I desire. I plan on sorting this issue out next year though as I am winterizing Tuesday and don't want to start something I can't finish this year.

[Straitcountry86]

Thanks for the info. I thought it might be the secondaries so I took the flame arrestor off and checked them out when the idle was up high, and they didn't look open. Unless they were opened so little that the naked eye could not tell.

[Jetlink]

I have isolated my issue to the secondaries when I did some runs this summer at various stages of my rebuild, I only had the high idle after I gave it enough throttle to cause the secondaries to open up. If they stayed closed, it would return to the normal idle. I would try and test your carb the same way. Do a run with just the primaries open and then return to idle. If it idles normally, I would say that you found your problem.

[Straitcountry86]

If that is the problem, do you think a carb rebuild would solve it?

[Straitcountry86]

Does anyone know if a carb rebuild would likely fix the issue?

[wotan2525]

Does anyone know if a carb rebuild would likely fix the issue?

I'd put my money on yes.

[Cusefan78]

I'm not the greatest with carbs but it sound to me like something electronic on the carb isn't working properly. If your turning off the boat to reset the idle it's seems electrical. With my limited carb knowledge I'm pretty sure these things are suppose to be tuned when the engine is warm. Could the idle or fuel be set too high and when it's warm it's staying at the high idle position. Take all that with a grain of salt but to me it's a carb issue.

[Straitcountry86]

Bump to the top as it is time for me to try and solve this issue.

[Moor]

you should have an electric choke on your carb, i'd start there and make sure the choke isn't sticking, causing a high idle. It happened to me once on my old ski nautique, it can be adjusted with a flat blade screw driver.
also check to make sure all of the throttle linkage, throttle plates/shaft and the cable isnt sticky and moves free through out the entire operating range. It may me time for a carb rebuilt also. Definately sounds carb related to me.

what rpm does it idle at when it idles normally?

[Straitcountry86]

you should have an electric choke on your carb, i'd start there and make sure the choke isn't sticking, causing a high idle. It happened to me once on my old ski nautique, it can be adjusted with a flat blade screw driver.
also check to make sure all of the throttle linkage, throttle plates/shaft and the cable isnt sticky and moves free through out the entire operating range. It may me time for a carb rebuilt also. Definately sounds carb related to me.

what rpm does it idle at when it idles normally?

Normal idle seems ok. Maybe 800 or so. Then when it sticks it goes up to 2-3000. I was thinking about the electronic choke and wondering if that could be it, since the problem does seem to be related to something electrical (since it goes away when you stop and restart.) Was also thinking about doing a carb rebuild as well. Are these fairly easy to rebuild or am I better off having a professional do it?

[Moor]

You can try to unhook the 12v power wire that attaches to the choke (the only wire on it) and unhook the choke linkage or wire it open, then see if your still getting a high idle. if not, then your problem is more than likely a misadjusted or bad choke.

I've rebuilt my fair share of carbs. If your careful, organized and take your time, its not very difficult. There's small pieces that are lost easily. Other than that its just cleaning and replacing gaskets for the most part.
If your somewhat mechanically inclined then i'd say give it a try