Motor Woes

[Steplift 72']

Originally Posted by bigshrimpin

Carbs are cake to rebuild especially on the older wh- carbs. If you're pumping the bulb and fuel is pour out the front of the carbs . . . the needles aren't seating (either from the needles being old or the floats not being adjusted properly). Get the kits and rebuild the carbs!! Also you might want to look into the low compression in that cylinder. You probably have a stuck ring . . . you might try decarbing (using power tune) the motor . . . spend a little extra time on that cylinder. If compression doesn't come back . . . I would pull that head and check the cylinder wall for scoring.

I agree that 20 psi lower on one cylinder is bad. I had a few psi differential on a V4 looper that caused the motor to run really weak. The old Mercury "Boathouse Bulletin" says a Merc 150 should push a V20 to 46 mph with a light load and about 42+ with 4 passengers and full fuel. If you're running 42 mph, have you lost any RPM? I had less compression loss than that on one cylinder of a 6 cylinder Merc and it wouldn't crank cold without starting fluid! If you can find someone with a borescope you may be able to get a look at the cylinder walls without pulling the head.