Runs Rough, Roy Penn

[roy penn]

'98 Mercruiser 4.3 Starts up easily enough. It immediately runs rough and dies. After a time by quickly going to high rpms (2000) it will level out to where it does not die but has low rpms (400 to 550) and runs rough. I have used carb cleaner plus added Sea Foam to about 10 to 15 gallons of last seasons gas to no satisfaction. I can go to carb while running rough and play with the butterfly which requires almost full choke and keep it running just fine. Any help greatly appreciated.

 

[Bondo]

I can go to carb while running rough and play with the butterfly which requires almost full choke and keep it running just fine.

Ayuh,.... Welcome Aboard,..... Sounds like the carb is fulla crud, a full on rebuild might fix it up,.....

Carb cleaner, don't do any good, til the carb is stripped of all it's pieces,....

Sea Foam don't make old gas new again either,....

Have ya checked the Contents of the fuel filter for water, 'n crud,..??

 

[roy penn]

I will check the filter and also think I will check the timing. Gotta go re-borrow my timing light from brother-in-law later this evening. Getting to that filter may prove a slow process. My 82 years will not let go long with my head down in the engine compartment, grin! Thanks for response. I was hoping the sea foam would help to clean it while running for awhile.