Carb is flooding mercruiser 4.3 v6

[adam125]

Hi All,
Over the winter i have had my engine out doing various work on it! this weekend i have installed the engine but the only problem i have is the carb is badly flooding the engine so much to it filled all the cylinders up with fuel! I took the carb apart and the float looks good I have not touched the carb In the last 6 months its just been sitting my garage, it work perfect before? Any ideas guys?? any help would be much appreciated?

Regards
Adam

 

[alldodge]

Hi All,
Over the winter i have had my engine out doing various work on it! this weekend i have installed the engine but the only problem i have is the carb is badly flooding the engine so much to it filled all the cylinders up with fuel! I took the carb apart and the float looks good I have not touched the carb In the last 6 months its just been sitting my garage, it work perfect before? Any ideas guys?? any help would be much appreciated?

Regards
Adam

Howdy Adam
With the float is in good shape, the only other thing that can cause flooding is either the float level setting or the needle and needle seat. More the likely the float setting is correct since it just started happening, I would check the needle and seat that the float uses to fill the carb, may need to be replaced

 

[MikDee]

It could be some stubborn debri caught at or behind the needle seat?

 

[NHGuy]

Check the clear line from the fuel pump to the carb too. if the fuel pump diaphragm fails the line fills with gas and could/should over fill the float chamber.

 

[Volphin]

Well there's an oil change in your future too.

 

[Maclin]

Engine can't be running with cylinders full of fuel, so I have to wonder how the fuel keeps getting pumped to the carb with engine not running...?

 

[adam125]

thanks for the tips guys when I finfish work tonight I will have another play around, The engine was running when it filled initially I noticed the carb was overfilling so turned the engine off lucky I did because I tried to turn it over with a socket an wrench and the engine couldn't turn over I removed the spark plugs and cylinders where full of fuel. Thanks for the help though much appreciated I will give you the verdict tonight

Adam

 

[MikDee]

Jeez! Engine filled up with gas!? It sounds like your fuel tank is pressurized!?

 

[Maclin]

If the fuel is coming out the fuel bowl J-Vents then it has to be the needle & seat adjustment or they need replacement, or the float can be full of fuel, or the needle/seat can be seeing too much pressure from fuel pump although if all this was fine last year then pressure is probably not the issue. If the fuel is just going directly into the manifold from the bottom of the carb then the power valve could be ruptured, but this will leak more slowly than you describe, probably not fill a cylinder that quickly..

 

[Maclin]

The power valvle comment was only for a Holley carb, your engine may have a MerCarb or other. Those have welch plugs in the bottom of the fuel bowl that can begin leaking, but that symptom is like the power valve problem in a Holley, slow leak directly into manifold causing hard start and driveability issues due to flooding.

 

[adam125]

Hi guys maybe it was the fuel tank pressurized I striped the carb last night give it a good clean put it back together an its working perfect now, so was very strange didn't find anything obviously wrong? Thanks for the help though much appreciated another problem solved

Regards
Adam

 

[MikDee]

Alrighty then, Glad you got it all working good now, whatever was wrong? Hope it stays that way, Thanks for the reply!