Reving to hard in on idle. Master craft pro star 190

[Jdhascamp]

Hello I have a 5.7 v8 Ford inmar engine 1988 I seem to be having problems with my boat it struggles to start then once it’s running it sounds ropey and start reving harder than it should do! I have had all the plugs out cleaned them also had the carb apart cleaned made sure everything is free but yet still it runs harder
Can someone please help me with my issue

Cheers josh

[thatsmrmastercraft]

From your description, it sounds like you may have a vacuum leak at your carburetor base gasket or the gasket between the spacer and intake manifold. To check this, with the engine idling at the lowest reasonable speed possible, spray carb cleaner along the gasket surface all the way around the carb. Using the straw provided with the can helps. If the RPM's increase, you found a leak. Leaks occur from worn/broken/dry gaskets, or from the mating surfaces not being completely clean and a new gasket being used.
This could be fuel or ignition related. Having a good distributor cap and rotor is important. Timing should be set correctly as well. Do you have points or electronic ignition? If points, they should be replaced annually and set using a dwell meter, not just point gap. If electronic ignition, coil + voltage should be same as battery voltage with key on/ engine off, and while running. Low voltage will greatly affect starting and performance.
Your carburetor could be to blame. Worn gaskets can cause vacuum and/or fuel leaks internally. Clogged passages will also cause your symptoms. How long since your carb was rebuilt?
Where are you located?


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