Mercruiser 305 flooding at idle

[pike hunter]

I don't post often but read on a regular basis and found very great knowledge on the site.Thanks in advance to take the time to answer. My Mercruiser 305 1992 with a Alpha one. The motor is prone to flood at idle or trolling. I read the Mercury service bulletin # 97-8 and they recommend some verifications that I did on the week-end. The recommandations are: to put the spring loaded needle and seal kit # 3302-9029 and the other thing is to change the Venturi cluster # 421, what is on actually is the 407. Would like to know if the 407 run leaner then the 421 and also should I go for the 2 changes or try the spring loaded needle first?

[SeaSkwurrel]

What type of carb is it?

[pike hunter]

Excuse me. It's a Mercarb, 2 barrels.

[cneste]

Sounds like a stuck float in the fuel bowl. I dont know if this would work like a car but her goes ( use to clean my holley 4 barrel like this)I would disconnect the throttle linkage to the carb. I would start the engine and rev it up a few thousand rpms(3-4) and try spraying a carb cleaner down the opening on the top of the carb and then try to suffocate it by putting a rag over the throat until it almost stalls. Repeat the process several times. Of course I would do this in the water so you wont burn out the impeller. Does anyone agree??Chuck