Strange fuel pressure issues
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From: Springfield, IL
Strange fuel pressure issues Let me first list the problems that I'm dealing with here:
1.) The fuel pressure very gradually bleeds off the longer I drive the car. Usually if I drive for around 15 minutes, it'll go from 61psi to around 57-58. 30 minutes takes it down to 52-53.
2.) When I turn the key on (once) to prime the lines, it doesn't usually prime up very much (as in MAYBE 10psi). If I crank it over a couple times, you can see the fuel pressure shoot right up to the 60psi, but it starts bleeding off pretty rapidly.
3.) When I shut the car off, the pressure bleeds off rapidly as well.
4.) If the pressure starts out at 61psi, at WOT, the fuel pressure drops down to around 52 or so and stays there until I let off the throttle. If I do the same at a lower initial psi, it drops off even more than that. I saw it hit 48psi once, from an initial 56, and that was all the testing I did.
The problems all started when installed a new fuel pump. At first the car wouldn't start, and that was traced to the fuel pressure regulator clip not being seated properly, letting all the fuel leak out. After that was put back on properly, I had the fuel pressure slowly bleeding off problem, so I figured I must have just fubared the FPR. I then installed a return line and an Aeromotive external FPR trying to solve the problem. Well it didn't.
Does anybody have any idea's about what could be wrong??
1.) The fuel pressure very gradually bleeds off the longer I drive the car. Usually if I drive for around 15 minutes, it'll go from 61psi to around 57-58. 30 minutes takes it down to 52-53.
2.) When I turn the key on (once) to prime the lines, it doesn't usually prime up very much (as in MAYBE 10psi). If I crank it over a couple times, you can see the fuel pressure shoot right up to the 60psi, but it starts bleeding off pretty rapidly.
3.) When I shut the car off, the pressure bleeds off rapidly as well.
4.) If the pressure starts out at 61psi, at WOT, the fuel pressure drops down to around 52 or so and stays there until I let off the throttle. If I do the same at a lower initial psi, it drops off even more than that. I saw it hit 48psi once, from an initial 56, and that was all the testing I did.
The problems all started when installed a new fuel pump. At first the car wouldn't start, and that was traced to the fuel pressure regulator clip not being seated properly, letting all the fuel leak out. After that was put back on properly, I had the fuel pressure slowly bleeding off problem, so I figured I must have just fubared the FPR. I then installed a return line and an Aeromotive external FPR trying to solve the problem. Well it didn't.
Does anybody have any idea's about what could be wrong??
Re: Strange fuel pressure issues it sounds very similar to the symptoms of a fule line leaking from the pump. what happenes is that the fule line from the pump to the top of the module either gets punctured somehow or the clamps you used come loose somehow.
make sure you use hi pressure fule injection hose ( better yet get aeroquip fule injection hose, doesn't mind being soaked in gas) from the pump to the top of the module. another thang to do is to use 2 clamps down where the pump meets the hose, prefrrably t-bolt clamps to insure that they don't gouge the hose. and make sure the clamps are tight!
hope this helps!
make sure you use hi pressure fule injection hose ( better yet get aeroquip fule injection hose, doesn't mind being soaked in gas) from the pump to the top of the module. another thang to do is to use 2 clamps down where the pump meets the hose, prefrrably t-bolt clamps to insure that they don't gouge the hose. and make sure the clamps are tight!
hope this helps!
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From: Las Cruces, NM
Re: Strange fuel pressure issues Sounds like a leak on the line from the pump to the sender unit. If you used a walbro pump, it has a 5/16" connection and the sender is 3/8" connection. Just about everyone uses just a single 3/8" hose. Which of course means you have to crank the heck out of the clamp to not get a leak. I have stated this many in many posts but no one really seems to listen. Really cranking the clamp down will somewhat work, at least to the hose breaks.
Gary
Gary
Re: Strange fuel pressure issues I would agree that it's probably a leak at the pump. I would also check the 'plastic' line from the tank to where it goes into the filter. Twice now I've had pressure problems and found kinks in the line. I have since replaced it with a better line.
Re: Strange fuel pressure issues At least you still have fuel pressure, my line burst in a couple places (can be seen in my link) and it would barely get any gas...like there was no "rattling" from being lean cause there was not enough fuel. Used a 5/16 hi press fuel INJECTION hose and fuel injection clamps...no problems now. Yeah the smaller hose is a not really easy to get on, but it goes on and doesnt get pinched by the clamps.
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From: Springfield, IL
Re: Strange fuel pressure issues I thought about the leaky line between the fuel pump and the sending unit, but that only makes sense to a certain degree. If it was leaking like that, wouldn't it cause lower fuel pressure all the time, not just after a 15-20 minute drive?
Also, this was a Racetronix Plug 'N Play system, and everything that was in the kit seemed like it was pretty simple to put together. The metal band clamp included with it was cinched down pretty tight on that hose. I made sure of this just because of all the posts I'd read in here regarding that same issue. I didn't want to have to drop the tank AGAIN.
Also, at one point I did have kinks in that plastic fuel line, but I replaced it with an unkinked one.
CAT3- You mentioned the line getting pinched by the clamp.. I believe that the hose used DID overlap a little after I'd tightened it all the way down. Does that potentially cause a problem, even if everything is tight?
Also, this was a Racetronix Plug 'N Play system, and everything that was in the kit seemed like it was pretty simple to put together. The metal band clamp included with it was cinched down pretty tight on that hose. I made sure of this just because of all the posts I'd read in here regarding that same issue. I didn't want to have to drop the tank AGAIN.
Also, at one point I did have kinks in that plastic fuel line, but I replaced it with an unkinked one.
CAT3- You mentioned the line getting pinched by the clamp.. I believe that the hose used DID overlap a little after I'd tightened it all the way down. Does that potentially cause a problem, even if everything is tight?
Re: Strange fuel pressure issues you don't have to drop the tank, do what a lot of people already do , cut an access panel!
swapping fule pumps becomes a 10 min job then!
swapping fule pumps becomes a 10 min job then!
