2000 500EFI - Fuel Issues - need expert advice if possible
 

I have 2 500EFI in a 2000 Formula Fastech with 200 hrs on them

Both motors 'act' like they are vapor locking from time to time. I have just accepted this as a normal (painful) fact of life that i must bleed the motors to get them moving from time to time.

Both have only the electric fuel pumps, no booster.

hooked up a pressure gauge to the bleeder schrader valve the other day and opened up the 'bleed' valve on the pressure gauge to let the fuel flow through the clear tubing.

I see that there is significant air in the clear tube as it flows out of the bleeder valve even after draining enough fuel that it should have emptied the whole fuel system, so am wondering if something else might be happening causing the symptoms of vapor lock.

Max fuel pressure was 38 on stbd and 42 on port so this doesnt seem too out of the ordinary, but the air in the fuel line seems like it could be a contributing factor to vapor lock.

Also ran a vacuum gauge just before the port side fuel filter to see if i had a leak in the suction side and the suction seemed fine. Read 2-3#s if i remember right.

Has anyone seen this before? Could bad fuel pumps cause air to be introduced or is something else going on?

Thanks,

Jim

ttt? Can anyone help me to determine what my next testing steps might be? Any experience with a similar issue?

Aftermarket efi fuel pump with and adjustable regulator and your done. Best thing I ever did with my 500efi.

Thx Black Baja. Can you give any details? Was the aftermarket pump a booster pump or an entirely new fuel system? What brand/model? About how much did the changeover cost?

Why did you need to do that? Just wondering because my 500EFI's are bone stock and I don't have issues.

What issue were you having? Only thing I have had to do fuel system was replace one of the pumps. That was a PITA!

My 500EFIs are both stock as well. forgot to mention that.

my buddy has a 1999 382 500efi blue motors same kind of symptoms, ended up going to premium fuel to get it to stop .Especially on hot days

That fuel system can hold a bunch of air. Since the fuel is pre-regulated, any air in the fuel rails can only get out by going through the injectors. It will take some time to get all of the air out. Put the pressure gauge on the rail and run the engine for a bit. You may even want to run it on the lake with someone monitoring the gauge. See if there are any fluctuations, pressure drops, etc. Do that for both engines.
If it had a leak on the suction side, it would probably not want to even pick up the fuel. Those pumps DO NOT have much in the way of suction. They are made to push fuel. So, I don't think that is your problem.
Eddie

Just for schits and giggles, has anyone tried an extended pick up fuel water separator head ? I know someone makes it.

Thanks Eddie, Since the boat seems to run perfectly when underway and i only see issues at starting time should i focus my efforts on pre-start fuel pressure or do you think that if i check in-operation fuel pressures that will tell me something about the fuel pumps? How large of a variation in that pressure would be acceptable underway?

I ran about a quart of fuel through by just turning the key to accessory position and back off a bunch of times and was still getting air in the fuel that was delivered when the fuel was tapped at the fuel rail.