Fuel Pressure not holding
- Thread starter dvernst
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I'm assuming you mean when you shut the car off...The fuel pressure at the rail drops quickly....
You only need 1 injector to leak down a little bit to lose the pressure on the rail...Either that or the check valve in the pump is not holding.
This should not affect the car at all while driving.
If you have another set of Injectors...swap them out just to see if the pressure holds,If It doesn't,It is more than likely the check valve....In which case I wouldn't bother with it until it's time to do another fuel pump.
If It does...start swapping the Injectors you took out back in one by one until you find the culprit.
You only need 1 injector to leak down a little bit to lose the pressure on the rail...Either that or the check valve in the pump is not holding.
This should not affect the car at all while driving.
If you have another set of Injectors...swap them out just to see if the pressure holds,If It doesn't,It is more than likely the check valve....In which case I wouldn't bother with it until it's time to do another fuel pump.
If It does...start swapping the Injectors you took out back in one by one until you find the culprit.
Yes the pressure drops quickly to about 20 psi, and then will hold steady. When I pinch the fuel feed line the pressure holds steady.
Jan Larsson
Active Member
- Joined
- Nov 22, 2001
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- 2,151
Same issues I had and I will be replacing my fuel pump with a Walbro 340 ... funny thing is I installed a Walbro 307 (or is it 305?) about 3-4 years ago so did not last to loong and now I have to drop the fuel tank again 
Same issues I had and I will be replacing my fuel pump with a Walbro 340 ... funny thing is I installed a Walbro 307 (or is it 305?) about 3-4 years ago so did not last to loong and now I have to drop the fuel tank again
I believe mine is the 307 also. It has been in there for about 8 years.
I had the same problem last year. I had the FP cranked and the 50lbs inj at full tilt and the car still leaned out at 60MPH or so at WOT. I bet it is your pump taking a dump. My car ran great one trip to the track and lean the next trip 2 weeks later. The car ran fine part throttle.
I think you are going to have to drop the tank and swap pumps. I hope I am wrong, but on my cars the holding FP after the car is shut off has been all over the place and my cars run fine. At least you can upgrade to the new pump from the 307 if you drop the tank.
for replacing the pump - you don't have to drop the tank. i know some people don't like cutting up their car but you can make an access door instead of dropping the tank....
LS2 Forums
LS2 Forums
Dont do that ^^^^ It is more work to take apart the interior, cut the floor, cut the tank, and then reasemble then it is just to do it right. If you have a lift and can take your time it should be no big deal. I did mine and it was all straight forward except for finding a way to drop the tank without bending the neck. I ended up doing it anyway..
Jason
Jason
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