Low pressure fuel pump PSI?
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Cargo Master
Joined: Apr 2003
Posts: 2,408
Likes: 5
From: Parkesburg PA
Low pressure fuel pump PSI?
I know the EFI high pressure pump should be like 35-38psi, but above 2500rpm's I'm loosing pressure. Got to say this, it still runs fine till about 16-18 psi. I want to check pressure between the low and high pressure pumps. The fuel pressure gauge I'm using has the connectors for it. It's high-end snap-on borrowed from my cousin (who's got his own shop). I just don't know what pressure to expect and what to look for to figure out what pump is bad. My cousin said just replace both pumps, but I did that 2 years ago along with both filters.
Is there any other issues? How about voltage at the pumps. They should be 12v correct?
Thanks,
Is there any other issues? How about voltage at the pumps. They should be 12v correct?
Thanks,
Senior User
Joined: Jul 2006
Posts: 462
Likes: 0
i dont know much about this area with efi's. i would look at all lines and check all filters. im not sure but i would think there would be some type of filter on the pump in the tank. i would also make sure all wires look good and are not damnaged
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Cargo Master
Joined: Apr 2003
Posts: 2,408
Likes: 5
From: Parkesburg PA
I went through the system about 2-3 years ago and replaced everything. Tank sock, tank low pressure pump, canister filter, booster pump, high pressure filter and regulator.
I'm loosing pressure above about 2500 RPM. I doubt the filters are clogged. The tank was clean and they've all been replaced 10-15k miles ago. So it's either the expensive HP pump that's easy to change, or the cheap tank pump that's a PITA to change.
It's frustrating because I was hoping after spending all the time and money to completely redo the fuel system I figured it would last many years.
Oh well... Guess I just have to start digging...
I'm loosing pressure above about 2500 RPM. I doubt the filters are clogged. The tank was clean and they've all been replaced 10-15k miles ago. So it's either the expensive HP pump that's easy to change, or the cheap tank pump that's a PITA to change.
It's frustrating because I was hoping after spending all the time and money to completely redo the fuel system I figured it would last many years.
Oh well... Guess I just have to start digging...
Elder User
Joined: Feb 2004
Posts: 830
Likes: 0
From: Indiana
Where did you check the pressure initially? On the fuel rail?
Have you tried to unhook and plug the vacuum line to the fuel pressure regulator to see if it makes a difference. I don't think your regulator is bad but it might help you figure out if the pump is possibly bad or not. With the vacuum unhooked it should have about 10 psi more pressure.
Have you tried to unhook and plug the vacuum line to the fuel pressure regulator to see if it makes a difference. I don't think your regulator is bad but it might help you figure out if the pump is possibly bad or not. With the vacuum unhooked it should have about 10 psi more pressure.
Thread Starter
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Cargo Master
Joined: Apr 2003
Posts: 2,408
Likes: 5
From: Parkesburg PA
I checked it at the rail. I also pulled the vacuum line and it did increase pressure, but it still drops off. I either have a failing pump or a bad electrical connection. I just wanted to see if I can isolate it by testing between the high and low pressure pumps.
Elder User
Joined: Feb 2004
Posts: 830
Likes: 0
From: Indiana
It sounds like your on the right track. Either the high pressure pump isn't working right or it's not able to get enough gas to build the pressure it needs.
You don't have any kinked hoses anywhere near your tank do you?
You don't have any kinked hoses anywhere near your tank do you?
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