New fuel pump keeps failing

[GMjr]

Replaced pump with a driveworks pump. Car runs great and then I turn it off and when I come back the pump doesn't prime or turn on. It's a 2004 century 3.1. It keeps happening nearly everyday. Then I go in the trunk check the connection and sometimes it starts but ive had to tow it twice now. Please help. I need to get my kid to school and doctor ect.

 

[NFortin198]

First I would check to make sure the connections are clean and tight. Then I would check the body ground as that seems to be a common problem. It is also a possibility that you have a bad pump, again this is common with aftermarket pumps. For parts that are difficult to get to, or to replace, your better off paying the price for OEM parts.

 

[GMjr]

Everything is tight and intact as far as I can see. Ground is good. Put a new relay in today because it wasn't too expensive. So that's ruled out. Pump works great when it's got power but either something isn't allowing it to prime for ignition or there is a broken circuit somehow that I cannot see right?

 

[wptski]

Everything is tight and intact as far as I can see. Ground is good. Put a new relay in today because it wasn't too expensive. So that's ruled out. Pump works great when it's got power but either something isn't allowing it to prime for ignition or there is a broken circuit somehow that I cannot see right?

IIRC, working on my 1990 Buick Century. Ignition switch to Run starts the fuel pump but when put in Start the relay keeps the pump running from a timed circuit, once started the ignition switch returns to Run position. You need a electrical diagram. I had a AllDataDIY account back then.

In Run, you should hear the pump run but in Start you'd need to measure the voltage at the pump or current draw.

There is or was at one time and my 1990 Buick had a dangling female connector near the firewall which is a fuel pump test connection. If you ground that wire the fuel pump runs. This was actually shown in the electrical diagram.

 

[ryenie]

There is or was at one time and my 1990 Buick had a dangling female connector near the firewall which is a fuel pump test connection. If you ground that wire the fuel pump runs. This was actually shown in the electrical diagram.

By looking at the wiring diagram this ability still exists, but it may not have a wire, just a terminal on the fuse box. Not exactly sure, but on one of the slots for the relay the relay has a leg that doesn't look to extend past the fuse box and is labeled fuel pump prime terminal, it doesn't go to anything so i would think this is it, however I think you have to apply 12volts to this terminal not ground, and the key has to be in off position. I've never actually used the terminal but i've seen it on many many cars.

I don't see any mention that the passkey system {security light} has any say over the fuel pump, so i think it would have to be between the fuel pump, fuel pump relay, and the wiring, or the pcm. Are these the same symptoms it was showing that prompted the replacement, did you replace just the pump, or the assembly as whole? It should prime for 2 seconds when you turn the key to run, if the engine isn't started within those two seconds it will cut off until you either turn the key back off and on, or crank the engine. This is now controlled by the pcm. If you have a test light or volt meter we can try and walk you through testing it from the relay or any thing else you may need help with,to see if the pcm is commanding it on as its supposed to or other areas to check. The Pcm applies voltage to the relay primary side so you can check to see if you have voltage from the pcm at the relay.

 

[HotZ28]

The Pcm applies voltage to the relay primary side so you can check to see if you have voltage from the pcm at the relay.

IIRC, the PCM supplies a ground (not v) to the relay to energize the relay. Please show a schematic to clarify my lack of memory.

 

[ryenie]

Please show a schematic to clarify.

, Given the location of the ground of the coil relay, it is what makes me think the 12v comes from the pcm rather than the pcm grounding the coil.