Engines stall at idle speed

I have twin 2004 Yamaha f225 engines.

Portand starboard engines stall at idle after high rev warm-up. The problem occurswhen I run them at cruising speed for several miles (getting them fully warmedup), then shut the engines off for a while. When I turn them on, the enginesrun for about a minute then stall. They won’t crank until bulb is squeezed,won’t stay running unless I immediately get to higher RPMs (say, greater than2500). Runs fine after that, even at idle speed. Thought it might be the lowpressure fuel pump but I ran it at idle at the dock for 1 ½ hours and it didfine. It only happens after I’ve been running for a while, turn them off andlet them cool down a little, and then turn them on.


Earlierthis year it was happening only with the port engine, but now it’s bothengines. This didn’t happen last year. This year I changed gas stations forfuel-ups. Could it be fuel related?

Anyadvice would be greatly appreciated.

Hello.


First of all, I would advise against high-rev warmups. The engines should be able to idle without any manual throttle being applied. And never idle it for 1.5 hours. You can potentially fry the computers that way. Try to keep it under 15 minutes max.


Check for leaks/kinks in all the fuel lines. The fact that you can squeeze the primer bulb after it stalls (and the engines turn over after you pump it) points to this being the #1 suspect.


Also, is your fuel tank venting properly? Next time the issue occurs, open the gas cap. If you hear hissing (i.e. pressure being relieved), then that's at least part of your problem, because lack of venting creates a vacuum effect in the fuel lines. So the pumps are constantly working against that vacuum.


If it's venting ok, then check for water or gunk in the fuel filter. If you find anything other than fresh fuel, clean out the fuel system.

Thanks. I'm taking the boat to my Yamaha tech next week and I'll copy him on your post.