Fuel Pressure Riddle
Thread Starter
Le Mans Master
Joined: Sep 2000
Posts: 6,303
Likes: 714
From: Bartlett IL
Fuel Pressure Riddle
I have been plagued by "No Fuel Pressure" for the last 2 weeks. I changed the FP Relay and Oil Pressure Sending unit along with the Charcoal Canister. At first, I diagnosed a problem with the Voltage Monitor circuit from the relay and the ECM ground circuit to the FP Relay. Both circuits had no continuity and FP was not turning on. I spliced new wiring for them and now FP turns on, BUT no Fuel Pressure.
I took fuel line apart at the filter and ran FP again. No fuel coming from the line. Replaced with new FP. Still no fuel. You can hear the pump but no fuel. Has 1/2 tank of fuel. I have also blown compressed air thru fuel and return line with no apparent blockage. There doesn't seem to be a leak in the lines. To test Ignition Module, I have sprayed starter fluid in TB's and motor will fire briefly. I have a pulsator coupling the FP with the fuel line in the tank. I'm wondering if that joint may be loose enough to allow fuel to leak back.
Any suggestions are welcome.
I took fuel line apart at the filter and ran FP again. No fuel coming from the line. Replaced with new FP. Still no fuel. You can hear the pump but no fuel. Has 1/2 tank of fuel. I have also blown compressed air thru fuel and return line with no apparent blockage. There doesn't seem to be a leak in the lines. To test Ignition Module, I have sprayed starter fluid in TB's and motor will fire briefly. I have a pulsator coupling the FP with the fuel line in the tank. I'm wondering if that joint may be loose enough to allow fuel to leak back.
Any suggestions are welcome.
Safety Car
Joined: Dec 2002
Posts: 3,655
Likes: 24
From: Charleston SC
Have you disconnected the line to see if it is pumpming fuel? If not it could be a bad regulator not allowing any FP to build. THe pulse damper is a posibility to test it just use peice of fuel line and a couple of hose clamps and replacce it.
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
he has done the line removal trick...
I assume the filter isn't blocked? But even then, SOMETHING would come through.
I would make sure the lines inside the tank are not causing all the pressure to bleed off. Also, test fuel flow at the tank end, literally. Not at the front. you may have a pinch in the metal lines.
I assume the filter isn't blocked? But even then, SOMETHING would come through.
I would make sure the lines inside the tank are not causing all the pressure to bleed off. Also, test fuel flow at the tank end, literally. Not at the front. you may have a pinch in the metal lines.
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Have you opened the line in front of the fuel filter after you replaced the pump??
If there is no flow there with the new pump and the supply line is not blocked and pump is runnning the problem must be with the pump assembly.
If the sock is not clogged and the pump is not defective look to the connection between top of pump and the delivery line, which I guess is the pulsator.
If there is no flow there with the new pump and the supply line is not blocked and pump is runnning the problem must be with the pump assembly.
If the sock is not clogged and the pump is not defective look to the connection between top of pump and the delivery line, which I guess is the pulsator.
Burning Brakes
Joined: Apr 2003
Posts: 783
Likes: 2
From: Wake Forest, NC
St. Jude Donor '05
When I was troubleshooting mine, I actually removed the relay and used a short piece of wire to jumper the pump in a constant on position then checked for pressure. Is there no fuel in the lines? If you hear the pump, and it's running, I would think it was likley trouble with the regulator.
And, sorry, but if you mentioned it, I didn't catch it... what year/injection system are you working with?
And, sorry, but if you mentioned it, I didn't catch it... what year/injection system are you working with?
Thread Starter
Le Mans Master
Joined: Sep 2000
Posts: 6,303
Likes: 714
From: Bartlett IL
Guys,
Thanks for the responses. The fuel line was disconnected at the back of the filter. I have run compressed air thru the lines as well with no apparent blockage. The pump strainer is brand new. I tested the pump with my Aeromotive VAFPR disconnected. Not sure if that could contribute to the problem but I wasn't getting Fuel Pressure when it was connected either.
I am going to replace pulsator with a solid piece of 3/8" fuel hose and
clamps. I'm pretty much out of ideas. Before I put the pump in, I turned on the ignition and had the motor buzzing.
Thanks for the responses. The fuel line was disconnected at the back of the filter. I have run compressed air thru the lines as well with no apparent blockage. The pump strainer is brand new. I tested the pump with my Aeromotive VAFPR disconnected. Not sure if that could contribute to the problem but I wasn't getting Fuel Pressure when it was connected either.
I am going to replace pulsator with a solid piece of 3/8" fuel hose and
clamps. I'm pretty much out of ideas. Before I put the pump in, I turned on the ignition and had the motor buzzing.
Safety Car
Joined: Dec 2002
Posts: 3,655
Likes: 24
From: Charleston SC
Dominic,
Once you stick the fuel line on there, if the problem isn't fixed i would bet you got a bad FP. Don't think it cant happen I chased my wifes car for 3 months because I just couldn't believe I installed a distributor with the same problem as the old one, geuss what I was wrong. I also had two brand new optis bad out of the box when i installed my stroker,but lucky for me they had compleatly diferent problems. Good luck and you have already done everything I would have done.
Once you stick the fuel line on there, if the problem isn't fixed i would bet you got a bad FP. Don't think it cant happen I chased my wifes car for 3 months because I just couldn't believe I installed a distributor with the same problem as the old one, geuss what I was wrong. I also had two brand new optis bad out of the box when i installed my stroker,but lucky for me they had compleatly diferent problems. Good luck and you have already done everything I would have done.
Le Mans Master
Joined: Dec 2004
Posts: 5,789
Likes: 8
From: Myrtle Beach SC
St. Jude Donor '05-'06
It is obvious that the pump is running.It should put out something.Try taking the line off and putting a piece in to a bucket and turn it on for a sec. Got fuel? If not pump is bad if you do have it then move on down the line. Is it possible the lines from the tank are reversed?I also know the FPR is a source of a lot of problems on these cars and I agree that it is wort checking/swapping out.
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