Hey everyone, this is for my '97Z. Looks like I might have another possible fuel pump/system issue. Symptoms are good cranking but no fire. I'm certain the car has gas, but because the car is stranded underneath a freeway overpass I can't hear if the fuel pump is turning on or not, which is always my cheap and easy test to see if the fuel pump is working.

I've already replaced the fuel pump twice on this car over the years; first by myself and then again through a shop when it was in for other repairs. Since it's been so long that I've repaired the fuel pump system I'm trying to remember the steps to diagnose the situation. I'm hoping you guys can help me sort it out. I plan to:

*check the fuel pump relay to see if there's voltage going to the connector. The fuel pump relay is behind the driver's side kick panel, right? I'll replace the relay just to see if that works.

*my Chilton manual says to check the fuel pump fuse, but I don't think this car has a fuel pump fuse, does it? Where is it then? I can't find it in the engine compartment fuse panel, the driver's side fuse panel, and I don't see any fuse for the fuel pump in my offical GM shop manuals either, just the relay.

*check for voltage at the fuel pump wiring above the rear axle.

Other than that I don't think anything can be wrong other than the fuel pump AGAIN. There are no DTC's and nothing else seems amiss. My "security" light is on but it has been since 1999 and that's never stopped the car from running. The only odd thing that happened was that my fuel gauge suddenly pegged to past full. Why can't I remember how I diagnosed this last time? I can't remember, and I hope you guys can give me a hand. Thanks in advance...

 

Shoebox's site has a great article on this. Hook up 12 volts to the fuel pump primer connector in the engine compartment to see if the fuel pump turns on. I believe its a direct connect to the fuel pump, bypassing all of the other connections, relays, solenoids, etc. If the pump doesn't prime when you hook up 12 volts through the primer connector, its the pump that's the problem.

 

 

Testing the pressure with a gauge is the only way to know, even if you can hear the pump run.

 

I stand corrected

 

Get a gauge on the shraeder valve locacted on the back side of the intake. It looks like a tire air valve.

You can buy a fuel pressure gauge from autozone.

 

Do you still have the fuel pump bucket in place? If not, and it is fuel pump related, not having the bucket in place may be a reason why fuel pumps are short lived.

 

Direct connection to the fuel pump? That sounds familiar, so I'll try that and also see if I get pressure too. Of course, I can't find my fuel pressure gauge from the last time I had this issue so I'll buy another one. You guys are right as usual-even if it does turn on that doesn't mean it's going to get the car started. What's the fuel pressure spec for key on, engine off? Idling? After shut off? Thanks guys, I'll let you know...

 

With the engine running w/out vacuum connected to the fuel pressure regulator it should be between 43 and 45psi. Once you get the fuel pressure gauge connected, try and start it and see what happens to the fuel pressure. IIRC without the engine running I think it primes to about 30psi? In your case, if it's not running at all there will be next to no pressure being read.
Anyway, you never answered my question, do you know if you are still using the fuel pump bucket?

 

I know when I installed the fuel pump the first time I used the bucket. I don't know about the second time because a shop did the install. Update:

Alright I got the fuel pressure gauge, put it on the car and there's no pressure at all during key on or cranking. I tried to connect the fuel pump to 12v directly and nothing. I checked for 12v at the fuel pump relay connections and there was power.

Where do I go from here guys? Is this the pump basically gone? I hate electric fuel pumps...

 

Sounds like your fuel pump went bad. Do you have the fuel pump access cut in the trunk. That will make changing the pump easier and quicker.

 

Check and see if you are getting power at the last connector to the pump under the car (during priming or when you have the prime connector jumpered).

http://shbox.com/1/fuel_pump_testing.jpg

 

Yeah I've got that cut out. This is the 3rd pump in 6 years and less than 5K. I need to find out why this car is eating pumps. Luckily the shop thst installed the last pump is willing to warranty the thing. Suggestions anyone?

 

When mine ate fuel pumps it was due to an underlying electrical issue that eventually burned up the engine harness too. Peel back the carpet behind the driver seat up to the top of the back seat and look for burnt up wiring. Mine was so bad that I just bypassed the original fuel pump relay/wiring and ran new power wire directly to the distribution block, probed for a good ground and put in a new relay to the ignition switch. It has been kicking *** ever since for the past few years/15k miles (approx).

 

What brand fuel pumps have you been using. That seems like alot of fuel pumps to go bad in 6 years.

 

The first pump that I installed was a Delphi unit. I'm not sure what the make of the 2nd one was since the shop put that one in; I was under the impression it was a Delphi also, but I'll see on Monday when the pump arrives at the shop. I'm tempted to swap it out myself but since it's under warranty then I'll make them do the work...