Carburetor Float Question

Prospector

Cadet
Joined
Mar 29, 2004
Messages
22
Engine is a 2001 Merc 60HP Bigfoot 4-stroke with carb. When laid up in October 2009 everything was running fine until several minutes prior to shutdown when engine started to stumble. Early April 2010 I changed spark plugs and changed lube oil and oil filter and drained 4 quarts instead of 3 out of engine. Oil was brownish gray color. I suspect at least 25% of drained oil is gasoline. I checked compression of each cylinder and got 185 psig-195 psig. T'stat checked out OK - opened at 120F. Temp. Sensor checked out OK with OHM and hot water test. I changed t'stat and temp sensor anyway. Enricher checked out OK with 12VDC test. Opened fuel pump and diaphragms looked OK but I changed the inboard diaphragm with plunger anyway. Engine now starts and runs rough and stalls at idle. Fuel tank bulb will not stay hard. I changed bulb and fuel line but bulb still will not stay hard. I now suspect a bad #1 carburetor float or needle/seat causing fuel to leak into oil. The #1 carb. is suspect because I find more fuel staining on #1 new spark plug more than on other 3 new spark plugs.
Question is: Can I change the float in #1 carb without removing all 4 carburetors as an assembly? Is there anything else that would give me the symptoms of fuel in lube oil (making oil) and tank bulb not staying hard?
 

verado7

Chief Petty Officer
Joined
Apr 28, 2009
Messages
511
Re: Carburetor Float Question

change the needles and gaskets and set the float height in all 4 carbs - i'm guessing they have never been done before ? 9 years is really good with out an overhaul -
 

Prospector

Cadet
Joined
Mar 29, 2004
Messages
22
Re: Carburetor Float Question

I should add: Primer bulb will get hard if I pump it fast but then it goes soft after a short time. This happens with engine running or not running. Seems that fuel is being leaked off by one or more of the carbs. I really need to assure this problem is with a carb. because boat is in a cable lift and I have no trailer and I am reluctant to remove carbs while engine is over water. I'm using walkboards to access rear of pontoon boat and the engine.
 

verado7

Chief Petty Officer
Joined
Apr 28, 2009
Messages
511
Re: Carburetor Float Question

yeah you said you changed the primer bulb -so carbs are leaking -
 
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