25 hp mercury outboard

Engine stalls out and will not idle and unable to keep it running under a load. I have rebuilt the carb, new fuel supply, new fuel pump and new plugs. What should I look at next? I would like to use before the snow flies

Re: 25 hp mercury outboard

There is a hole on the diaphram that needs to be matched up correctly to your carb. Make sure you have the correct one.

Re: 25 hp mercury outboard

Fuel pump should be part of the carb on this engine. Make sure the gasket between carb and intake is not installed incorrectly blocking the pulse hole that drives the pump. If all looks good, and carb is indeed clean, I have seen alot of leaks around the gaskets that are sandwiched either side of the reed cage. My two cents...

Re: 25 hp mercury outboard

I had to rebuild my carb on 25HP mercury outboard, When i was done had the same problem. Engine would run for a bit then quit. When the engine was about to stall out i could pump the bulb and it would run fine. So i figured the gas was not being replaced in the carb bowl. This is what i found; I rebuilt the carb in the garage. My kit came with a couple different mounting gaskets so i chose the gasket that looked closest to the original, matched it up to the carb and it looked great, however on the motor one of the ports was offset from the port on the carb. looking at the old gasket the hole for this was elongated, the new gasket the hole was not so it covered up the hole on the engine. I elongated the hole on the gasket, and it worked fine. Good luck!!