1999 Chaparral 2330

[John12756]

My chaparral 2330 revs up upon starting to 2000rpm and after a while it will come back to normal, this only happens when the boat has run for an hour and then cut off. When restarting after 5 minutes it revs to 2000rpm, any ideas? Thank you.

 

[SST]

My 1987 235 does the opposite. When it is a cold start and I have to pump the shifter while cranking, it will sometimes rise to 2000rpm. Then I'll adjust the shifter to a lower rpm. If my engine is warm from a recent run, all I have to do is turn the key and it starts and settles at 900rpm with no movement of the shifter.

Are you usually pumping the shifter at all during a hot start?

 

[John12756]

i never pump the shifter on cold start up, it fires up great and settles at the appropriate rpm, after a 1 hour run and the cut the engine off and when i go to start that's when i get the revving up to 2000, i think its a heat sensitive issue. If i let the engine rev for a while two to three minutes it will come back and settle where it should be.

 

[Doc]

What does your temp gauge show? If you have an infrared heat sensor you could verify the temp gauge and check temps on other areas of your motor. Seems like the engine is trying to cool down.

 

[John12756]

Temperature says 165 and it only does it when it's hot, if I ride for an hour and sit for an hour, it will start right up, no problem

 

[Doc]

You say after a while it comes back down to normal. About how long is awhile?

 

[John12756]

Five minutes

 

[Doc]

Five minutes

Wow. That is extreme. I've seen it where they might idle up a bit for 5 seconds then go back to normal. 5 minutes is crazy. and if you rev it up it still settles at 2k rather than where it should?
Just trying to understand the issue. Right now I have no clue on what to do to stop this behavior.

 

[John12756]

Yes when you are sitting still after running for an hour, cut the engine off, wait 5 minutes, start again, it revs to 2000rpm and you Rev the throttle once or twice, it still stays at 2000rpm, wait about 5 minutes and it comes back to normal idle speed, crazy situation

 

[willbaker13]

Throttle position sensor?

 

[John12756]

I don't even know what that is, but u might be right

 

[Iggy]

About 7 years ago I basically had the same problem. I can't remember the name of the part. But it was a small plunger type of a part. In other words, it moved something to do with the throttle body. There were two wires that controlled it if my memory is right. It was on the port side of the engine. Hope this helps?

 

[John12756]

We need to get a little closer than that, check your paperwork on your boat, a part name would very helpful, thanks

 

[jfkirby]

possibly the Idle Air Control valve. Might be what Iggy is referring to above. It's a solenoid plunger that moves in and out of the throttle body to regulate amount of air going in, and if faulty can cause idle RPM issues.

 

[Iggy]

Thats it!!

 

[J Kyle]

Might be worth the time to clean/replace the IAC filter first. Its kinda like that filter screen nobody knows about at bottom of cool fuel module It could possibly never been cleaned or changed out. New IAC valve is $185-$205.

 

[Iggy]

Keep in mind that both Merc and Volvo are GM blocks. So you can find that part for less.