Creeping engine Idle

[Chad]

Hello. I've got a 2003 Nautique with a 330 Excalibur PCM.
My normal tech went out of business and I'm trying a new guy. I'd like to get the jump on what's wrong with my boat.

The past summer my boat after warming up only...…(.cold there were no problems)..... my idle would creep up to 1000rpm and higher. I'd shut down the engine and restart and the idle would go back to a normal 700ish. This acted mostly in perfect pass but not always.
Any ideas to what's wrong are greatly appreciated.
thanks
chad

[Infinity]

My initial guess was perhaps the carb needs to be re-built (assuming this is a carb boat). Not familiar with this specific engine since I have not owned one but I had a similar issue with a Sea Ray I/O Mercruiser I used to own. The previous owner had used ethenol fuel and some of the ports were clogged causing erratic idle and acceleration issues. Re-built the carb after soaking it overnight and cleaning really well....as well as had the timing adjusted. The issues went away after that. (I also drained fuel tank since I knew the guy had let the boat sit tho I know this does not sound like your issue).

However, if you can turn boat off, restart it and then the idle stays normal, then its likely something else. Figured I would toss that idea out there tho since a good carb clean is good anyway if it hasn't been done for a while.
I assume you have also changed the fuel filters? Pretty sure that engine has an inline fuel filter between the fuel tank and the engine, as well as the FCC paper fuel filter which requires removing the FCC canister to replace which is mounted to the engine.

Have you replace the distributor cap and rotor in recent years? Corrosion can cause all sorts of issues like this. Probably smart to replace the ignition wires and plugs as well if its not been done for a while.

This link may give you some ideas to look into and part numbers if the same engine:

http://www.correctcraftfan.com/forum...-tune-up-parts

This link seems to also have some good info:

https://www.justanswer.com/boat/9ig0...e-details.html

[Chad]

Thanks for reply

the engine is fuel injected and I replace all my wires and cap/filters every two years. And only put ethanol in under rare occasions.
throttle link?
heck I’m afraid to do too much.
i like paying experts

[Infinity]

Right on, hopefully its a good mechanic who will be able to narrow it down and solve for you.