99 gran prix 3800II help please

[tblake]

Have you tried the fuel pump resistor bypass? Check the tips and maintenance subforum.

[72240z]

How bad is it that the relay just isn't there?

This just gets better and better.

Is it identical tot he fuel pump relay? Because I have a spare I could use to check.
The numbers seem to match in the pic.
http://www.automotiveforums.com/vbul...d.php?t=658282

EDIT - Upon closer inspection there are no pins for that relay. The holes are there but no pins. I just read that its all post 97 1 vins? Pretty sure this is a 1 vin.

[BNaylor]

Originally Posted by 72240z

EDIT - Upon closer inspection there are no pins for that relay. The holes are there but no pins. I just read that its all post 97 1 vins? Pretty sure this is a 1 vin.

Is this a GTP or GTX model? Otherwise it sounds like you have the NA SII 3800 VIN "K" (GT or SE) and no fuel pump speed control relay. Check the 8th digit of the VIN number to be sure.

[tblake]

Good question Bob. I asked a few posts ago if it was an NA or SC 3800 but got no response so I thought I'd throw the fuel pump resistor bypass out there.

[72240z]

It's n/a, I thought n/a would be assumed before supercharged...I appreciated the tip though and checked right away regardless.

So are we out of ideas yet ? What would cause a pressure drop like I'm seeing besides the regulator or pump? Both of which seem to check out. Pump and filter have under 3000 miles on them.

[tblake]

You could hook up a voltmeter to your pump's grey wire and ground and check for proper B+ while you are running your car to see if the voltage at the pump dropps off.

[72240z]

Ya that was the next step, should be constant 12v no? I'm going to break out the multimeter today or tom and check voltage and resistance on the ground.

[tblake]

sound good. 12V constant at the punp while its running or at prime.

[doctorhrdware]

I have a dvm that will record the peak voltage. That makes it easy for one person to take the voltage readings.

[tblake]

I usually just yank the relay and jump it so the pump gets a constant 12V. Makes it easier to go to the back and check the voltage.

[72240z]

My mother was in the hospital today with a check infection so I didn't get a chance to check. What pins are you jumping? Would make my life easier.

I'm going to check the injector resistance too, I forgot up until now.

[72240z]

I get a constant 14.3v at the pump even when the pressure drops and it stalls. The ground checks out surprisingly well, maybe since I fixed the body ground.

Borrowed my friends alldata since mine is still mia and looked up actual GM pressure test procedure and it fails the prime hold test. They say it shouldn't drop more then 5psi after prime in 10 min and it does. Or more then 2psi at 10psi, which it passes. That leads to 3 options.

FPR
Leaking injectors
Fuel pump

I need fuel line shut off adapters to test leaking injectors and fpr, which I don't have nor can I find, prob a dealer tool. The lines (pipes) are so hard I can't just clamp them either. The fpr has passed every other field test I gave it so I feel it's fine. At this milage I doubt it's leaking injectors, plus in all my searching out of problems on the 3800II not once did I see that.

I'm going to return the pump and try another. The pressure bombs to like 0 when the car stalls and while I was testing the voltage and someone was reving the motor the pump really didn't sound very good. Not in my opinion anyway.

Opinions on all that? You guys quit yet?

[tblake]

if the fuel pressure bomb's to 0, car stalls, and the pump still has constant B+, I'd say that you have found your problem. Is the fuel pump exchangable/returnable?

After the fuel pump primes, exactly how low does the pressure drop?

[72240z]

Sorry for the late reply.

You know it didn't give it that test, completely slipped my mind to find out. Once it failed the 5psi test I went down the line to the 2psi test. Then the 3 optional problems the diagnosis chart showed. It dropped fast though (from max prime 49-52ish psi)5psi in the 1st min then maybe 15-20 by the end of the 10min test.

The pump had a 1 year replacement warranty but they supplier says he is out of stock until the end of November. After some complaining I am getting a refund, sadly it's mail order so I'll have wait a few more days. As soon as I receive it I'll pick one up local and see where I stand.

I really hope this is the end of it all. This car has gone from a good thing (gift to my mother from my brother) into a nightmare for me.

[worktester]

have seen that issue once before
and it came down a sensor that regulates the fuel to the injectors on the fuelrails