I can help you but I may not be able to get you back on the water before your boating season ends. You can send me the ECM and I'll check it out for you, no charge but like I said it may not make it back to you before your season ends.

I actually helped my neighbor check his out. I have a fuel pressure gage so we hooked it up to the fuel rail. When you turn the key on, we could see the fuel pressure come up to normal range. We then started the engine and the pressure would hold for a few minutes then the pressure would become irratic and then go to zero. Obviously the engine would die out. It sounded like both fuel pumps were working but the fuel pump at the cooler was quitting. Merc has changed it now to where you have to replace the cooler and pump as an assembly. If the computer isn't beeping, in most cases I have found the problems to take me back to the basics.(fuel and spark) If you do not have a fuel pressure gage then go to a local auto parts store and either borrow or rent one. I will be happy to assist you any way that I can. We have been running 496's and have logged over 1500 hours so we have had our opportunities to learn a few of their weaknesses.

Thanks much for the help. I am out of town for the next week but will work on this when I get back.

Trippin - I may take you up on your offer. I'll get in touch with you when I get back.

i know this is a very old thread but I’m having the exact same problem did you ever figure this out?

The guy hasn't even logged into this site in 14 years. I don't think he's going to be replying.

it was worth a shot though right? i have the same exact problem , do you have any idea what it is?