1999 Oldsmobile Alero No Power to fuel pump

Tiny
BZOMERLEI
  • MEMBER
  • 1999 OLDSMOBILE ALERO
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 120,000 MILES
My son's Alero will not start. When we turn the key ON, the fuel pump does not run.

I checked the fuel pump fuse and relay, both are OK and both are getting power when I turn the key ON.

I was originally having problems with the security light being stuck on, I fixed that by using the resistor method to fool the BCM that it is receiving the correct resistance from the key cylinder.

Any idea what the pin outs are at the wiring harness near the gas tank? I'm wondering about the single plug side, not the dual plug on top of the tank. I'm thinking there may be a short in the harness someplace that is preventing power from getting all the way to the pump.

Any other suggestions?
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Thursday, June 18th, 2009 AT 4:21 PM

7 Replies

Tiny
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I purchased access to the website and now have access to the wiring diagram.

I learned that the wire harness at the fuel tank has a medium gauge gray and black wire that run the pump. The back is grounded and I verified 0 ohms from that pin to the chassis ground.

I also verified 12 volts across those pins as well as DC amps when the key was turned to on. The volts and the amps dropped after about 2 seconds. I think that is normal.

The question is why is the pump not running? Is there something else inside the pump, preventing the pump from spinning up for those 2 seconds? Note: the fuel tank is still drained, does it require a minimal amount of fuel to even turn on? I think I'll put 2-3 gallons in it while waiting for a response.
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Thursday, June 18th, 2009 AT 8:54 PM
Tiny
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I unplugged the fuel pump harness from the body connection and then manually connected a 12volt source to the gray and black leads. The pump runs and pressurized the system. I reconnected the harness and started the car, it ran for 5 seconds until the pressure dropped. The pump does not run when connected to the harness.

One more thing, there is an old remote car started installed in this car, I found it when trying to bypass the Passlock II. I'm wondering if something there is interfering. I have disconnected it with no change. When connected, it does lock and unlock the doors when the key is turned, so I think it is functional.

ANy help would be appreciated.
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Friday, June 19th, 2009 AT 11:13 AM
Tiny
BRIAN 1
  • MEMBER
Sorry nobody helped yet, I didnt see your question, I'll try and help.I would start by scanning for any theft deterrant codes, sounds like more of a passlock problem, you said you put a resistor in to by pass it, usually a bad idea to do that, I would just start by fixing the security light first(probably just needs an ignition switch)very common on these. Then perform the 10 min relearn and see if it starts, if it doesnt then check spark and fuel pressure. When there is a theft deterrant problem or code these vehicles will not start and only run for 5-10 seconds, that is also the reason why you only get power at the connector for 5 seconds, if the BCM see's a problem in the sys it will go into theft mode and disable the fuel pump. Post back with what you find.
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Friday, June 19th, 2009 AT 12:02 PM
Tiny
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The Passlock is fixed, the security light does not come on anymore. It was solid on, before I did the resistor bypass. Once I added the resistor, I did the 'new key learning procedure' the light went out, and has not turned back on. Doing research on this, I learned that when the key is first turned on, the fuel pump is only energized for a few seconds, and wil turn back on when the key is set to start or the engine is running. From what I can tell, I am getting voltage at the wireharness, but the pump does not run, even for that 2 seconds.

For your other questions, I am getting spark but not fuel. I can get the engine to run for a few seconds by using aresol starter fluid. I can also get the car to run a few seconds by manually energizing the fuel pump at the tank wire harness to pressurize the system. I am getting fuel pressure at the fuel rail when manually running the pump.

I'm wondering if there is an issue with the other wires going to the fuel pump assembly. I think one set is for the fuel level (seems to be working) and the another is for tank pressure.

I was unable to get any codes from the DEI Avital 3200 starter, but I was able to put it into 'valet' mode, this should bypass the Avital system.

Thanks
Brent
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Friday, June 19th, 2009 AT 12:37 PM
Tiny
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I'm more than a little peeved right now. Turns out the fuel pump relay WAS bad. The second thing I did after checking the fuse was check the relay. I took it down to AutoZone and they plugged it into something and declared it 'good'. Since it was 'good' I started down other paths. I must have spent another $100 on parts and tools, when I needed to spend $15 on a new relay.

Anyhow, enough ranting, I tell you how I figured it out. The website pointed me in the right direction. One of the first steps was running a fusable jumper from the + on the battery to pin 30 on the relay socket. That worked. On a whim I pulled out the A/C relay and put it in the fuel pump socket since it was the same part number. Viola, it worked.

I'm thinking the the relay was working enough that it would pass the test at AutoZone, but failed when it was actually delivering current.

Brent
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Friday, June 19th, 2009 AT 3:36 PM
Tiny
BRIAN 1
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Sorry I wasent more help, I got to you question to late.I would have steped you in the wright direction, but atleast you got it fixed. One again sorry for the delay. Thank you brian
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Friday, June 19th, 2009 AT 8:20 PM
Tiny
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Brian,
Sorry, did not mean to imply I was peeved with you or the website, I was directing that at AutoZone and their relay test.

I'm happy it is fixed, but irritated that the second thing I checked after resolving the Passlock II issue turned out to be the eventual culprit.

Ah well, I learned a bit more, I guess that counts for something.

Brent
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Friday, June 19th, 2009 AT 9:52 PM

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