Help fuel problems.........

[yamaha_2000r6]

1999 donzi z3250 with twin mercruiser MIE 7.4 MPI engines with velvet drives. Problem is I can start both engines drive to a swim spot and after sitting for a couple hours neither engine will start. This has happened twice now and the last time I removed one of the fuel water separators and there was no fuel in it. The pumps both run when you turn the key and the engines try to start but only sputter and die. I pulled one line to the starboard tank and can suck fuel through it manually as well as blow back through the line. The boat has two tanks with a line running to the rail with shutoffs and 2 lines going one to each engine. I've read similiar posts with 1 efi engine and some were going to try the fuel pump but I can't imagine both pumps being bad. Plus the last time I got towed in and by the time I was back to the slip the boat started right up again. Is there anything I can check short of going to a dealer? Everyone is booked up on texoma. I read a post on an anti-siphon valve but not sure how it works. I assume the fuel is draining back into the tank or getting air from somewhere but am so lost on what to try.

 

[P 0 P E Y E]

Re: Help fuel problems.........

Assuming that there is plenty of EMF in the batteries and the problem is fuel starvation I would try this:

Inspect and try to understand the path of fuel. understand the fuel tanks, fuel supply from each tank and the shutoff valves.

See if you might be able to determine that one or more valves are in an improper position.

A cross over valve could be causing your fuel starvation problem. It may happen after shut down and take some time for the air and fuel in the extra line to clear.

Just a hunch. And it costs you nothing but time to check into. Best of luck and keep us posted.

 

[Jeepster04]

Re: Help fuel problems.........

As far as I know the fuel filters shouldnt empty out when you shut the engines off. Have you tried filling them up with fuel then putting them back on and seeing if they start?

Does the system have check valves?

 

[yamaha_2000r6]

Re: Help fuel problems.........

I will try maybe shutting off the crossover valves when I shutdown and see if that helps. Where would a check valve be located? I have a vacuum gauge and will try and rig it up so I can see if the pumps are pulling ok. Just can't imagine both pumps going bad at the same time.

 

[yamaha_2000r6]

Re: Help fuel problems.........

Well took the boat to the marina and ofcourse they haven't been able to fix it. Guess I will be without a boat on the 4th. Might decide to go pick it up and do some more shadetree mechanicing on it.I'll keep you posted if I find the problem.