Pete280

I have been havin a problem with the motor dieing every time I go out, 2000 502 mpi, boat runs great, all of a sudden dies every so often, it wont restart, to get it restarted I started replacing filters then I realized all I have to do is take the filter off and put it back on (same one) Filter is always half full when removing it.

This is what I have done so far, removed and replaced siphon valve, the tank pickup is a 5/8" tube welded to tank so I cant check that. replaced hose to fuel filter, replaced fuel pump, relay and regulator. ran a scan on the motor and no codes were present.

should I replace the fuel lines going from filter to pump? they look fine but maybe they are flexing when I'm running and are getting kinked?

I'm pretty sure the fuel is getting cut off every once and a while, other than that the boat will run great,

Any thoughts?

thanks

Pete280

I should also add that I poured the fuel out of the filter and no water was present, I have run approx 40-60 gallons through the motor since I have had this problem going on so I dont think it's a fuel issue.

txriverrat2001

When you say it dies - does it just shut off?? or surge? It may be coincidental or the time it takes you to remove the filter that it starts back up.... A fuel pressure gauge will verify pressure ... And I would probe the purple wire to make sure you're not losing power (12V) through a loose connection or corroded connection.....

ezstriper

also, a long shot but ck the tank vent, seen them clogged with spider crap and such....Rob

Pete280

thanks, when it dies it is abrupt and shuts down. I checked the tank vent and there is a screen under the cap so I dont think anything could get beyond that.

after looking at a manual last night I did realize that my vaccum line from the regulator (on cool fuel) goes directly to the plenum, the drawings show it teeing off and one line going to a fuel damper under the plenum. It has been like this since a rebuild last year so I dont think it's the problem but I'll stick my head up there and find the fuel damper.

KAAMA

iTrader: (1)

Kinda sounds like it might be your coil going bad. (???) The engine will run fine for a while and when the coil heats up (gets too hot) it will shut down/off which is usually typical of a bad coil. Then once the coil cools down the engine will restart and eveything will act normal again until the coil gets hot again and the process repeats itself, but what do I know---I just kill bugs for a living.

SB

iTrader: (1)

The nipple that the the water seperator spins onto is the fuel outlet of the seperator that goes to pump.

This nipple only goes down and inch or so and therefore is not in the 'reseorvoir' of fuel in your seperator when your seperator is ony half full. It needs to stay completely full of course for your pump to draw fuel.

Either you have an inlet to seperator from tank issue (restriction or air source) or you have mucho vapor coming from return line that goes back into seperator. Make sure the reurn line is not too close to a heat source and getting to hot.
Low psi liquid is much apt to vaporize than high psi fluid at same temp.

As mentioned , the vent can cause this fuel flow restriction too of course. Tank fill cap off and blow thru vent hole to make sure not clogged.

Reckless32

Pete did you get it fixed? I saw you out taking pics durng the poker run last weekend outside of Lynnhaven. Should come raftup with us at Chicks for lunch. Had a blast.

Pete280

Thanks for the suggestions,
I'll try blowing out the tank vents this week.

I had a FP gauge hooked up last weekend and it was 38psi and went to zero when it died, seems to only happen in 1-2' chop and above 4K, I loosened the filter let a hiss of air out and it ran great the rest of the day.

maybe the lines from the sep to pump are getting kinked when in choppy water? what would cause too much vaccum pressure in the system?

I should have stopped by Rick but since I wasnt in the run I dont like to free load, looked like a great day.

fstboater

A cracked fuel pick up line can do this put a piece od clear line in and look for air bubbles. Most pick up tubes have a screen in them blow it out if if you cant pull the tube to ck it try removing the anti siphon valve. You can put a vacuum gauge in the inlet side to see if something is blocked. And make sure you have 12 volts to the fuel pump you can do this with a jumper wire from the battery straight to the pump to go around the harness and relay.Good luck