Help on 2003 Fountain twin 6.2s
 

Alright guys need some help on my boat. Seems like when I take boat out and it warms up my starboard motor starts to die. sometimes it will flutter and come back sometimes it will die and ill have to bring other motor back down to idle and the starboard will fire right back up with no issues. The only codes that come up are 94 pitot pressure, 75 fuel level circuit high, 119 steering position circuit low, 104 lake/sea temp circuit high, 130 trim sensor circuit high. Im guessing these are all ghost codes. serial number on starboard engine is OM626568. had muffs hooked to boat and let idle today and never got it to die or have the problem. I wiggled every wire I could think of to see if it was a loose connection. Ive had multiple people look at it and it never acts up or has any codes at idle. only does it in the water under some load and rpms. Gonna try to hook up a fuel pressure gauge tomorrow and make sure its not a fuel pump issue and getting adequate pressure to the rail which if I recall is 48-53 psi correct? Only other thing I can think to check would be crackshaft position sensor and though about swapping them on motors to see if the problem would follow that. other then that im not sure what my problem is. thanks for any help guys.

Fuel pressure should be 43 psi at 1800 rpm

The current codes have no issue with current problem

What maintenance has been done this season?

Take the fuel filter off and dump it into a clear container to see if there is anything but clean gas

Problem started last year. Over winter both fuel filters were replaced on both motors as well as the cap and rotors. Same problem persists this year but only more frequent.

Do start by checking fuel pressure.

Your serial number (assuming Bravo drives) shows a boost pump and the cool fuel HP pump.
https://www.mercruiserparts.com/350-...-0m600000-thru

Port motor pressure is to high and may have a clogged screen or issue with the regulator on the cool fuel module.

Starboard motor is within spec, and while it was holding the pressure did you have any symptoms? If it wasn't acting up then don't know if it was fuel pressure or something else. Need it to act to get an idea of the issue.

If the motor is running out of fuel it could be the pump, antisiphon valve on the tank, regulator

Don't know much about the newer stuff so here's my .02. Since it runs great on the muffs when you force water into the impeller, maybe there is a water pressure sender when under power in the water you aren't getting enough water thru the impeller. You say it gets worse the longer it runs. Something is going progressively bad. Just thinking outta the box.