Audio Guy

Update...New Pump installed on Friday...All was well Friday all day, Friday night, Saturday ran a half a tank of fuel through it perfectly. Coming back to the marina entrance and started to come off of plane...starboard motor (Problem motor) died ...pulled out of the way of other boaters and restarted..Ran rough and kept stalling the way back to dock. Dumped the fuel filter this morning and spun on a new one..Motor would start up and die instantly when no throttle applied...with a bit of throttle would run but rough. Breather sounded like a jet plane sucking air!..But eventually cleared up. Went out for another run and it was perfect for about 30-45min....Then SAME thing.
Kind of at a loss here (again)
Almost feels like Water in Fuel but explain the Start up and quit immediately syndrome...Almost IAC Motor symptom ...

It also almost always has a Lazy start when warm...Port motor fine...Batteries load test fine..Guessing weak starter but only guessing.. Timing is Bang on the money and advances properly ..

Spark Test was good while we trouble shot Friday..

Any advice would be greatly appreciated...

Gimme Fuel

Sounding like a ground/electrical issue with slow cranking. Could be intermittent voltage drop/power loss to motor. Id take off all the heavy power leads and inspect lug ends at motor and at switches/battery too. Also inspect the fusable link on starter hot lead.

F-2 Speedy

iTrader: (6)

Pull the IAC and leave it plugged into the wiring harness, while watching the IAC cycle the key to on and see if the motor is activating, key on and off should move the plunger in and out, you also need to check the TPS setting/.

wybmabiity

If "Lazy" means longer than usual cranking time, then I'd be suspicious of dirty or otherwise defective injector(s). An extended cranking time when warm can arise from an injector failing to completely close when the engine is shutdown, allowing a small amount of fuel to leak into the intake and cause flooding during starting. I've heard this referred to as "hot soak". If its just dirty injector(s) (maybe from deficient fuel stabilization at storage time?) I guess you might correct it it with a dose of injector cleaner. Don't know to what extent this could contribute to the originally-described problem. This was an issue back in the late 90's with GM MPI engines which used Bosch injectors, and GM replaced defective injectors under warranty to correct it.

But if "Lazy" means slow cranking then ignore the above.

BUP

iTrader: (9)

^^^^^^^ they were Multecs and GM replaced them and finally decided to quit making the Multecs in 2001. I know because I have the GM bulletin all about it and the reason why they needed to be replace. Anyways the lb rating of the 500 efi multecs are different than what the auto side and what the Corvette used,. Merc racing used the MULTECS all the way up to 2004 even thou they were NLA thru GM. Merc had a ton still on hand so they used them.