1998 Correct Craft with 5.8 PCM Surging while Idling and excessive smoke from exhaust

[LouShaw]

Boat has new plugs and fresh oil at the proper level.

Any guidance would be appreciated! Thanks

[jpwhit]

Possibly bad valve guide oil seals, or blown head gasket. What color is the smoke?

[LouShaw]

Thanks for the response. Grayish smoke

[Jonny Quest]

GT40 engine or carbureted? If GT40, a surging or "loping" idle is a known issue. Replacing the Idle Air Control valve, Manifold Absolute Pressure sensor and Throttle Position sensor usually fix the loping idle. All these parts are Ford / FoMoCo and you don't have to buy PCM parts that are waaaay too expensive. Another known problem is the fuel pressure regulator. These parts are fairly easy to replace and you don't need a PhD in internal combustion engines to figure it out.

If you have a carby engine, dark gray / grey smoke can be an indication of an overly-rich air/fuel mixture.

lease provide additional details.

JQ

[LouShaw]

Thanks JQ. The engine is a 351 W I imagine some of the same issues may cause problems as the GT40

[LouShaw]

It has a Holley Carb

[Jonny Quest]

OK...dark gray smoke can be a sign of a carb out of adjustment. When was the carb last re-built? At idle, remove the spark arrestor and look down the throat of the carb. Can you see fuel dripping?

[LouShaw]

I will try this. My brother and Took the carb off and cleaned it. I bought the boat last spring and I dont know if its ever been rebuilt. Its mostly sat most of its life. It had less than 200 hours on it when I purchased it.