dumb question but befuddled merc 140

inkrat41

Cadet
Joined
Jul 19, 2010
Messages
8
I have a 1985 3.0 Mercruiser
M C M 140
Serial Number #5372984
Rochester 2 G C Carburetor


I get everything running great in the driveway for 1/2 hour or better. new distibutor, timing set, new plugs (ngk) wire set , fresh gas, great compression, new fuel filter, water separtator good fuel pump new etc. I'm not a complete moron (have some parts missing) been a shade tree mechanic for years. take the boat out runs great for 15 minutes no overheating no issues then she starts to sputter, hard to restart and chugs to the dock any advice?
 

Bt Doctur

Supreme Mariner
Joined
Aug 29, 2004
Messages
19,093
Re: dumb question but befuddled merc 140

remove and drain fuel sep filter into a clear container looking for water.
check anti-syphon valve at tank.
 
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