Having a real problem on one of my 500efi's. Thought maybe vapor lock, now symptoms have changed. First had problems with restart after 10 minutes shutdown. Now, even at idle, loose fuel pressure, also noticed over 3000, drops from 25/30 to 10/15 lbs. However, unlock the vapor lock, (vapor lock show no presuure upon attempted restart) now after a short rest, gauge shows 30lbs with ignition, of course drops once started after a few minutes. All symptoms are getting worse .... any ideas?

A friend had a very similar problem with starboard engine on new triple Fountain with 525s. After spending about 3k checking everything, it turned out to be a big glob of silicone that would get trapped over the outlet bung inside gas tank. It would move off bung when bounced around then get sucked back over bung when being operated. Very difficult to diagnose cause but an easy fix once observed. Sounds like it might be same or similar problem but object could be trapped in outlet.

Check any filter you have and replace. If this is not the problem then go after the pump. Don't run a port EFI engine with that little pressure or you will lean it out and destroy it.

Roby

Dealer just changed filters 3 hours ago, but I will try again. (any chance the water separator, after winter fuel) Hope its not the pump, mounted under the engine..... chance one would have to remove the engine. Curious why you say "port motor" ... it happens to be the starboard, although I get the point. Thanks

Do you have fuel cutoff switch(es)? Make sure they are working and flowing properly.

did they replace the small steel high pressure filter on the top as well? this filter gets overlooked alot. also check that the supply pump is in working order. the high pressure pump does not pull fuel well so if the supply pump is weak the high pressure pump cant maintain pressure.
Steve Schmidt
Competitive Edge Marine

Trouty,

2000, with 150 hours. Port motor has the retro 2nd fuel pump, starboard never needed it. That's how I knew the vapor lock problem. Strange how problem is "changing", as mentioned, was only upon a restart after running (like vapor lock) now obvious with pressure gauge while running, then upon idle. Thanks so far, please continue your thoughts. btw, I have now ordered the retro kit for this motor also, but even when I had vapor lock, it never acted like this.