Fuel issue?

[Jakal]

I have had this car for a few months now and have been been working out all the problems the previous owner caused. The problem I am currently working on is that sometimes when I shut the car off and come back to start it, it will have zero fuel pressure. I know this because there is a pressure gauge under the hood. If you let it sit or tap on the filter it seems to fire up. Then when its running it looks like to gauge is pegged at about 100psi for fuel pressure. I am a little confused because it has the t25 turbo and as far as I can tell stock fuel system. So would a clogged fuel filter cause this to happen or am I going to be looking into a sensor or something?

 

[Soccerguy136]

The stock fuel pump has a check valve that keeps pressure in the line. If that part is leaking, you just need to replace the pump. However, the car should still start, just take a few extra cranks to build back up the line pressure.

It could also be the fuel pump nipple o-ring causing it to leak pressure back into the tank instead of keeping it in the line. This will usually cause the car not to start, but can be harder to diagnose if it's just slightly leaking.

If you aren't smelling fuel in or around the car, it will most likely be one of these two things. If you are, then you have a fuel leak somewhere.

Also, where is your fuel gauge hooked up? 100psi of fuel pressure is incredibly high. It should only be about 43psi at idle with the vacuum hose to the fpr unplugged. Do you have an aftermarket afpr?

 

[JMAR]

I don't think a clogged fuel filter will cause the symptoms your having.. but then again the parts like 10 bucks and easy to change...

Great info soccerguy by the way..

Good luck

 

[Jakal]

The pressure gauge is located on top of the fuel filter right down under the battery. After looking at the psi while the car was running it is at 60psi. I do not believe that I do but the car is new and the guy I bought it from had no idea of what it had. How would I tell if I have one? How would I lower the fuel pressure because based on what you said the pressure is about 17 psi high which would explain the slight slugish ness and the 20mpg. Also the car only runs outs of fuel pressure every once in a while. Like today out of the five times I had to stop, only once it ran out of pressure then took a couple mins of cranking the engine it came back.

 

[Soccerguy136]

You should easily be able to tell if you have an AFPR. Just do a google search of what one looks like and see if you see it in the engine bay. It should have 2 fuel lines and one vacuum line coming off of it.

That said, if there is a gauge on top of the fuel filter, then you most likely don't have one, as the gauge would be located on the AFPR in that case.

When you looked at the fuel pressure, did you unplug the vacuum line to the fuel pressure regulator like I said?

If you did and it's still that high, then most likely the previous owner put in a 255lph pump, which will overrun the stock fpr and cause a higher fuel pressure.

 

[Kod]

Possible mpi relay?

 

[Jakal]

I have not had this issue for a few days now but it is doing something a little different. Now when I start it sometimes it will almost die and you hit the throttle and it will sound like its not getting fuel then out of the blue it revs up normal. Also when driving it cold it idles normal but when you get to operating temp and come to a stop light the car drops rpms to like 2-300 rpm and runs no chugging or stalling just sits at 2-300 but only after its at operating temp. When its below operating temp its at like 650rpm idling.

 

[spyderdrifter]

A clogged fuel filter will actually drop your fuel pressure. You should still replace your fuel filter anyway for peace of mind. Since y out haven't had the car very long, you don't know when it was last replaced. It's just good maintenance to do.