Diablo

ANY BODY ELSE HAVE TROUBLE WITH VAPOR LOCK. I HAVE A 2000 358 WITH 502'S AND LAST WEEK DOWN IN FL. MY PORT ENGINE WOULD'NT RUN ,THOUGHT IT WAS A FUEL PUMP BUT WAS'NT IT APPEARS TO HAVE BEEN VAPOR LOCK, THE NEXT DAY IT RAN FINE.

GO4BROKE

Mpi's run 40-45 psi fuel pressure, and shouldn't vapor lock. Your motors should also have the "cool fuel" fuel cooler set up from Merc, further lessening the chance of vapor lock. I would check fuel pressure, filters, and for water in the gas. Are you sure fuel is the problem? A loose wiring connection killing the ignition is more likely. Check the kill switches and the ignition switch connections. Good luck!

GO4BROKE

Oh yeah, if you decide it really was vapor lock, I would be very suspicous of the quality of the fuel you got. If the octane was lower than the 87 rating or if the ried vapor pressure rating was low, the fuel would be very volatile and boil off easily, causing your vapor lock.

Vonbongo

I haven't heard of the 502's doing it, but vapor lock is a known problem on the 500EFI's.

I believe merc has a service bulletin about it: http://www.outdrives.com/bulletin/se...9/mcsb997x.pdf

It mentions winter grande and alchol as possible problems, also excessive heat in the engine compartment.

Diablo

I can only go by what the service dept told me.The engines are still under warranty and like i said the next day the boat ran fine they couldn't find anything wrong, the fuel pressure was rite at merc specs, they also checked the anti siphon valve because they had several cases of manufacturers using the wrong valves causing the fuel pumps to burn out early, but that was'nt a problem.Thanks for the tip on the fuel next time i'll buy fuel at another marina and see what happens.

CelticPride

Trep, I have twin 454 Mpi's and have had problems this winter with vapor lock. I first began to have the problem in November...after shutting down and comingback to restart like an hour later, my port engine would run for a few seconds, then die...would not restart for a while. I still have the probelm but it is not as chrinic...I let the engines idle for a bit before shutting down, to cool them..I open the hatch, etc...I also replaced the covers that cover up the water sparator..which I had previously removed...all of this seems to work.

hp500efi

I have had on occasion the same problem. Turned out to be a "overly heated" engine compartment. From now on, I raise the hatch when idling or sitting in hot temperatures.

Never had the problem since.

Looney Tune

May sound silly, but make sure your fuel overflow vents are not clogged. Also, maybe you can recalibrate the brain boxes. It is not too expensive. If interested let me know and I will look for the guy's name, he is in Lousian.