'78 Merc 800 carb questions

[brooksk]

I have an old '78 Merc 800 that sometimes stalls out after slowing down from near full throttle. It almost feels like the motor can't get enough gas or air when I open the throttle back up. After ~1-2 minutes the motor kicks in and revs up like it should. I've changed gas tanks and now run off of portable. Changed fuel lines. Have the correct 50:1 gas/oil mix and had the idle mixture set by a boat serviceman. The motor runs fine otherwise: startup and full-throttle good, just only when I try to accelerate. My carb seems to be a central bowl type (2-carbs total). Could my acceleration problems be due to the throttle linkage sticking, choke stuck, main jets clogged, or inlet needle/float clogged or incorrectly adjusted.

 

[mellowyellow]

Re: '78 Merc 800 carb questions

for me and my 1150 it was the fuel pump diaphram....<br />not broken or torn, just got weak over time.<br />it's a cheap try at least. <br />or just another thing to think about.<br />good luck <br />M.Y.

 

[petryshyn]

Re: '78 Merc 800 carb questions

Try running it with the cowling off. If this cures the problem, inspect the motor mounts for sag. Some also have a bellows seal that tears. (exhaust gas leaks by sagging mounts and chokes engine)