after a long day of trouble shooting, checking spark, taking the fuel filters off and seeing a lower than expected level, tracing the fuel lines all the way back, removing and cleaning all connections, he found....a problem with the anti-siphon valve at the exit of the fuel tank, I don't know exactly what was wrong, but he did something to it (probably cleaning out varnished fuel deposits) and then the engine no longer would slowly run out of fuel. I took the boat out of the harbor and ran it fairly hard for about 15 minutes including a couple full throttle runs and no stumbles or stalls.
Now for some follow up issues.... First, by logic, I do not think the mech fuel pump was bad since we replicated symptoms with the electric one (though maybe not quite as bad). the mechanic (who I have some language barriers with) insists it was a two part problem, but I really want him to pull the electric pump back off and put the oem one back on. Anyone disagree with this? When he tested the pressure it showed 7-8 psi as he ran the engine off starting fuel while testing the pressure on a rubber hose added to the rigid fuel line. To me that was good, but he said it should be higher at idle so when under load it maintains in the 8 psi range, plus it could have been constrained by the plugged up anti-siphon valve. It was also a janky install in my opinion with a power wire running off the coil and no oil pressure cutout, no heat shrink connections (simple crimp), etc.. While I hate to mess with a running engine, I think having STBD with an electric pump and Port with a mechanical will look really bad upon time to sell, let alone how it was installed.
Let me know your thoughts on this. Also, I had bought a cheaper aftermarket carter pump -- better to put the old oem one back on or the new carter (unpainted).
Secondly, I ran both motors for a short time at absolute full throttle and Port pulled 3800 and Stbd (the side with the issues) only 3400. I had to back off the throttle substantially on the port side to match RPMS. It was a bit choppy so I couldn't hammer it for long, but enough to be sure of this discrepency at high rpms.
Do you think the cause of the lower rpms is the fuel is still somewhat constricted? Any other explanation?
Thanks everyone for the help - would love to hear back on this before meeting with him again tomorrow. I feel the R&R of putting the OEM pump back on is worth it even if it doesn't go well and the electric one has to be put back on. I hate non original stuff and i know it reduces the boat's value come sale and survey time.
