Its not my fuel pump. So wtf. - Maintenance and Repair Forum

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Its not my fuel pump. So wtf.
Thursday, May 27, 2010 1:47 PM
Put my second fuel pump in the cav today. Dropped the tank twice in the last 2 weeks. I bought the dealer pump. It primes great. But the car still dies. Im flipping out right now. It ran great for 2 minutes after i put it in, primed it 10 or 12 times, and started it. Then it died, and continues to stall everytime i try to start it.

Please, somebody help me out here..




Re: Its not my fuel pump. So wtf.
Thursday, May 27, 2010 2:26 PM
You have a fuel pressure gauge hooked up to the fuel line, right? (if not, rent one for 20$ at Autozone). Watch what happens during prime, during start, and running/stalling.

Did you replace the power-plug on the fuel pump (common GM fuel pump issue)?

Did you replace the fuel filter?

Did you test the relay/fuse?

Does it try to run if you throttle it?

Sorry If you have answered these things already...but I forget easily.



Re: Its not my fuel pump. So wtf.
Thursday, May 27, 2010 3:41 PM
What is the proper way to test the relay?

Also, i did not replace the connector. I do have one though.

Everything else i have done. I suppose ill go pick up a fuel pressure guage now.



Re: Its not my fuel pump. So wtf.
Thursday, May 27, 2010 6:19 PM
Update..

The relay is fine.



Re: Its not my fuel pump. So wtf.
Thursday, May 27, 2010 8:44 PM
Yea, should hear a relatively loud click/feel a click (have someone turn the key) when the key turns on. There is a better way to test it, but that seems to work for me. But it seems that issue has been eliminated.

I think honestly theres just air in the lines. The pressure gauge will allow you to bleed the lines, and thus eliminate that possibility.

When I replaced mine I primed and bled a few times, then cranked it several times and it fired, backfired, then died. Then I primed again and it fired up! haven't had a problem since.

So, Priming procedure:

1. Connect fuel pressure tester to schraeder valve on fuel line
2. Turn key to "On", wait for pump to stop (have someone else in the car to handle the key), turn key "Off".
3. Release pressure (and hopefully air) with the side button on the tester.
4. Repeat until when the pump pumps, it builds pressure in the line (IIRC ~ 45-55 PSI)
5. Once you get pressure in the line, crank it over.
6. Be patient, I let the pump do its thing and give it a few seconds to chill before cycling it.

Also, just an FYI - Keep AT LEAST 1/4 tank at all times, our pumps are liquid cooled (fuel), so as the tank goes below 1/4, the pump heats up, and causes pre-mature failure.

Keep us updated.





Re: Its not my fuel pump. So wtf.
Thursday, May 27, 2010 11:37 PM
I will try this, thanks for your help!



Re: Its not my fuel pump. So wtf.
Friday, May 28, 2010 5:11 AM
NP



Re: Its not my fuel pump. So wtf.
Sunday, May 30, 2010 10:39 AM
Update.

I have not dropped the tank again to replace the connector, though i do have it. I spliced into the power and ground for the fuel pump i'm running currently. After starting the car it read around 13.20 volts consistently. I had my girlfriend rev the car after a minute of problem free idling, and that's when things went wrong. The 13 volts stayed constant, but as the RPMs came down, the car struggled to regain a healthy idle, and died.

This is the story for every start. However once the car dies once, i cannot get it to start for more than 2 or 3 seconds afterward unless i let it sit a few hours.

Also, there is clearly air somewhere in the lines, i believe it is at the pump itself. When priming for the two or three seconds, the pumps makes an aweful gurgling noise, but after a few primes, clears up.

Still dead in the garage. Any more ideas? Could this be the work of the bad power harness at the pump?



Re: Its not my fuel pump. So wtf.
Sunday, May 30, 2010 10:41 AM
Gonna go pick up a fuel pressure tester.

Wish me luck



Re: Its not my fuel pump. So wtf.
Sunday, May 30, 2010 5:25 PM
The pressure read about 30 PSI upon my first prime. After relieving pressure and a ton of air. I could not get it past 1 or 2 PSI. The pump sounds strong when priming (past the gurgling sound of gas & air).

It seems like there's a leak somewhere, but i am not leaking fuel.

Help?



Re: Its not my fuel pump. So wtf.
Sunday, May 30, 2010 7:00 PM
How many times did you prime and release pressure?

Are you low on gas?

Did you re-use the in-tank filter?

Something must not be connected properly, there really shouldn't be any more issues.

I doubt the connector is the problem, given the fact that the pump has been turning on and off reliably.

Double check all of your connections, the only thing at this point I can think of is the possibility something came loose while putting the tank back up.








Re: Its not my fuel pump. So wtf.
Sunday, May 30, 2010 10:54 PM
I just got done dropping the tank and replacing the connector just to scratch that off the list..



Car runs great =)

Who'd of thunk it?

I still cannot believe that something as small as a wire harness would cause all this to happen.

Thanks Jack! Wouldve had a hard time without yah.



Re: Its not my fuel pump. So wtf.
Monday, May 31, 2010 6:35 AM
Yea, no problem. Enjoy!

Don't forget to leave at least 1/4 tank at all times.



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