Mercarb 2bbl flooding after engine stops

[toneybrown]

So, last summer I had this same issue. Stop the engine and fuel would drip down, then the boat didn't want to restart until all the fuel evaporated or I opened up the throttle to let it air out. Last summer I installed a new needle, seat and float. Adjusted everything and the flooding problem stopped.

Today I pulled the tarp off the boat, reinstalled the points and changed oil. Had a hard time getting the engine started, but some starter fluid seemed to work. I killed the engine and fuel was dripping into the carb at a much higher rate then when I had the issue last year. A very fast steady drip.

I pulled the carb off, checked the needle and seat. Readjusted the float to 14mm and 27mm drop. I am currently using the spring. As that is what was in it when I first tore it apart last year.

So, is there some other adjustment I need to make? Is the float adjustment I found incorrect? I measured from the bottom dot on the float to the rim of the carb.

Any help is appreciated.

 

[Rick Stephens]

Might measure fuel pump pressure. But likely you got crap in your carb. A little goes a long ways in needle valve seats. Could also be a float with a little leak, and it's getting heavy. Or simply a bad float height adjustment.

 

[toneybrown]

I'll pull it all apart and clean as best I can. I'll double check my float adjustment. I don't have the necessary equipment for a pressure test. Not sure how exactly to do it.

 

[toneybrown]

One thing I left out of my original post. I actually pulled the carb off twice. After the first time I took it off I just adjusted the float a little down. When I put the carb back on I was not getting any fuel to the jets, and the boat wouldn't run at all. When I unbuttoned the top of the carb before removing the whole thing, there was something like a pressure release or vacuum release from the bowl side. I'm assuming this would be normal if the carb was sucking air out of the bowl instead of fuel?

 

[Rick Stephens]

The Mercruiser manual for your motor will give you highly detailed instructions on how to rebuild that carburetor. It needs a kit and done exactly properly. Sounds like you've been guessing, that won't cut it if you want the motor to run right.

 

[toneybrown]

I took the carb apart again and found some debris in the seat. I think it may have fallen in from all the crap blowing around the air right now. Should have done a better job of making sure everything was cleaned out before putting it together.

Now I just need to figure out why my idling is wonky. If I get it to idle around 650rpm it will eventually bog down and die. Almost like it ran out of gas. I have to pump the throttle before it will restart. It will then idle for several minutes before bogging down and dying again. If I increase the idle to closer to 800 rpm it seems to idle as long as I want, but the rpms jump up and down 150-200 rpm. Not sure what is causing the fluctuation. I may change the points to a new pair I have just to make sure they aren't causing a problem.

 

[Scott Danforth]

the fluctuation is from crap in your fuel and carb.

pull the carb apart, clean it thoroughly, then assemble with a new gasket kit.

most gunk in a carb is pumped in to the tank