Fuel pump not working?

Hello,

If you have verified that both the fuel pump relay and fuse are in good working condition, and you have already replaced the fuel pump itself, there are a few other potential causes for the lack of power to the fuel pump in your 1999 Oldsmobile Alero. Here are a few troubleshooting steps to consider:

Wiring issue: Inspect the wiring harness that connects to the fuel pump. Look for any signs of damage, loose connections, or corrosion. Ensure that the wiring is securely connected and in good condition. Use a multimeter to test for continuity in the wiring to confirm if there is any break or short circuit.

Fuel pump control module: Some vehicles have a fuel pump control module that regulates power to the fuel pump. Check if your Oldsmobile Alero has a separate control module for the fuel pump and test it if possible. If it's faulty, it may need to be replaced.

Fuel pump relay socket: The relay socket itself could be faulty, causing a poor connection between the relay and the socket. Inspect the socket for any signs of corrosion or damage. Clean the contacts and ensure a good connection.

Ignition switch: The ignition switch is responsible for sending power to various components, including the fuel pump. A faulty ignition switch can result in a lack of power to the fuel pump. Test the ignition switch or consult a professional for assistance.

Fuel pump driver module: Some vehicles have a fuel pump driver module that controls the fuel pump's operation. If your Alero has one, it may be worth checking and testing this module.

Thanks,
Alex
2CarPros

Okay, In the diagrams below I have included the wiring diagrams (enlarged just to show circuit) for the fuel pump circuit. It consists of a fused power supply to the pump, PCM controlled power, a 4 pin relay, the fuel pump, and three (3) ground locations, along with six (6) wires and a junction box. I also have included a link on how to use a multi-meter for you down below. Please go to the link and familiarize yourself with how to use a multi-meter if you need to.

https://www.2carpros.com/articles/how-to-use-a-voltmeter

Okay, I need you to get me a voltage reading at pins E6 and E8 at the under hood junction box (diagram 1). Please make sure you have your key in run/"on" and not start. Please get back to us with what you find out.

Thanks,
Alex
2CarPros

Hello again,

Sorry, what I need is to get a voltage reading from pin E8 in the Underhood Junction Box. It will have the dark green wire with a white stripe going to it. You will need an assistant trying to start the vehicle while you are getting your reading. Let me know what you find out please.

Thanks,
Alex
2CarPros

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.

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