HELP! FP leak at large quick disconnect!?!

**alacran** · 07-01-2008

So on Saturday i replaced the cheap Carter fuel pump with a PRJ FP and to be safe i also replaced all of the o-rings on the fuel rail, injectors and the quick disconnects.

Basically, the system is not holding pressure on shut down and i cant find a fuel leak anywhere even while its running.

Last night i took apart the large disconnect b/c as the fuel pressure drops i can make it hold pressure by holding that line a certain way. The first o-ring (in front) looked fine. I pulled the second o-ring and it stretched too far. So i figured i found the problem i will change the o-rings and be done with it.

Fuel pressure still drops! I was so frustrated that i got a worm clamp on there hoping it squeeze the seals tighter but it was no good. I am desperte for ideas here. All i can think about right now is diagnosing this all over.

Stick a FP gauge on the line before filter and see if its leaking before engine and so on.

Any thoughts? TIA.

EDIT: FP at cruising condition is 350 kPa and at WOT FP increases to 400 kPa

solution tighten the hell out of the worm clamp on the FP corrugated tube. Deadheaded the fuel pump at the filter and the pressure dropped. I hesitated but then decided to pull the fuel pump assembly loose and watched that thing drip fuel as it was leaking.

Moral of the story - when the instructions say snug it means really f'in tight or as tight as the little worm clamp will take.

TDCRacing · 07-01-2008

How long does it not hold pressure for? so you prime the pump by turning the key on then turn it off and how long doen it hold pressure for?

**alacran** · 07-01-2008

under a minute. After it primes the needle on the gauge starts falling.

**Arkanzan Wheeler** · 07-01-2008

Mine is doing the same thing, on mine it is a supercharger gasket vacuum leak. The fuel pressure regulator is vacuum operated, if there is not enough vacuum it will not pull enough fuel pressure. I have a new L32 gasket in the mail right now...

TDCRacing · 07-01-2008

do you have a tuner or a scan tool so you can check your short term and long term fuel trims? that would tell you right there if it was because of a vacume leak.

**alacran** · 07-02-2008

I have an aeroforce gauge...i will set it up.
I thought the vacuum decreased the fuel pressure. In other words, when there is boost you get max FP. The vacuum applied to the regulator decreases the fp.

Actually GM instructs you to unplug the vacuum line when checking FP. Either way, i will check for a vacuum leak later.

Any more thoughts?

**Reptile** · 07-02-2008

It could be bleeding off at the pump?

**alacran** · 07-02-2008

Originally Posted by Reptile

It could be bleeding off at the pump?

How? I want to check that but the hardware store i went to yesterday did not have anything that would match the threads of the fuel filter.

So far i am going to check for fp at the fuel filter (after i figure out a way to hook up my gauge to it.) and setup my scan gauge for LTFT and STFT. I will not be able to get a hold of the tech 2 til around 7/14.

Anything else?

**Reptile** · 07-02-2008

Well, what I was getting at is it could be leaking inside the tank. Fuel pump could be bleeding pressure off, or one of the lines going from the pump to the top of the sender where the lines connect.

I mean, who knows lol