Odd Fuel psi symptoms..w/in

[KnightFire]

My fuel pressure is set to 50psi at the AFPR, when I turn the key to the ON position, I hear the fuel pump prime the system my pressure goes up to about 40psi and immediately back down to 0psi. I swapped out the injectors with 44lb/hr Accel's and after doing so, my pressure loss stopped (the injectors leaked down).

Now all of a sudden I have NO pressure unless I start the car, then it stays right at 50psi as set...when I turn the car off...back to 0psi.

I've checked the system and I have NO fuel leaks!

I do have a new Aeromotive AFPR, I'm just wondering if these are the symptoms of a ruptered diaphram? Can anyone confirm? Other possible problems?

TIA

KnightFire

[Kevin - Blown 95 TA]

Is there a check valve in that fuel pump that is not working?

[KnightFire]

Not to my knowledge...here is the AFPR I have now:


http://216.242.145.16/products/produ...l?p=12&large=1





KnightFire

[Joe 1320]

Pull the vacuum line off the regulator. If the diaphram is ruptured, you'll have fuel in the vacuum line.

[KnightFire]

Just looked at that...no fuel in the vacuum line.






KnightFire

[Joe 1320]

Did you do the "sniff" test? There might not be visible fuel, but sniffing the vacuum line will give you an indication of fuel or not.

Just to confirm, what you say is that turning the key to run but not start, the fuel pump doesn't pressurize the rails? If you are getting pressure at that point, but shutting the car off the pressure immediatly drops to zero, that is normal if your fuel pump doesn't have a check valve.

[KnightFire]

I didn't actually sniff the line, but there didn't appear to be any fuel coming from the AFPR at all...I'll try that later though.

***Edit*** I just sniffed the line and I did smell fuel...however the line was dry as a bone?!

It was holding pressure just fine until recently, even with the new AFPR and injectors it would hold 50psi after the key was turned off.

As it is now, I turn the key to the ON position to prime the fuel, the fuel psi goes to 50psi and immediately falls to 0psi, while the key is still in the ON position.

To get the fuel to stay at 50psi I must start the car...as soon as I turn it off...back to 0psi.


KnightFire

[MN6WS6]

My car started this about 2 months ago. Last month, the fuel pump went out while I was 70 miles from home resulting in a $135 tow bill. My suggestion, go spend the $170 on a Walbro fuel pump now and put it in, or pay $100 to tow it home AND $170 on a fuel pump. I learned the hard way.

[KnightFire]

I have a Walbro 340lph now...less than 1yr old.


Thanks for the suggestion anyhow!

I just picked up a new filter, its the only thing on there thats older than 1yr old. Hopefully its something as simple as that...I'll know tomorrow.



KnightFire

[Kevin - Blown 95 TA]

My bet is that it is either the check ball in the pump, a loose hose coming from the output of the pump, or an outside possibility one of the new injectors is leaking.

[KnightFire]

Hmmm, Ya might be on to something with the pump's check ball. I doubt its an injector, the psi drops WAY too fast for it to be a leaking O-ring or something in the injector. The psi drops FAST.

I'm gonna replace the filter and have a look around the fuel tank...I'd really hate to replace that pump again...



KnightFire

[Kevin - Blown 95 TA]

Dean, Did you drop the rear and all that s___, or did you cut the hole in the trunk above the tank when you did the pump? Just curious...

[KnightFire]

Originally posted by Kevin - Blown 95 TA
Dean, Did you drop the rear and all that s___, or did you cut the hole in the trunk above the tank when you did the pump? Just curious...

I did it the ghetto way, I cut a hole in the floor of the hatch. I haven't welded it back together yet...thats probably a good thing right about now.

Why?

How can I check to see if its the check ball? Any simple tests?



KnightFire

[Kevin - Blown 95 TA]

If you can dead head the pump back there into a gauge, then you could see how fast it falls off. If you jump terminals 30 and 87 in the fuse box (with the FP relay out) the pump should run.

[KnightFire]

Hmmm I'll see if there is any way to attach a gauge to the pump, I don't think that there is, at least not one where I can drop the pump back in the tank to get fuel.

I know the pump is working, I can hear it when I turn the key on and it supplies the fuel just fine while running...or maybe I'm not understanding what by-passing the FP relay and jumping the two fuses would do, other than test the pump for operation. Would there be something else to look for while doing this that I'm missing?

I think I'm gonna replace the fuel filter, put my old AFPR back on and if neither of those fix it...replace the pump. I really can't think of anything else...opinions?


KnightFire