Fuel Pump Relay help! 2003 Olds Alero
04-28-2010, 04:51 PM
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Fuel Pump Relay help! 2003 Olds Alero Buddy of mine's daily beater has been using up relays. Obviously this could be a few simple things. From looking up the P/N of the relay, it has a max of 35 amps on the load side. Also knowing that there are design tolerances incorporated into everything these days, the fuel pump does not run off of 35 amps. I would guess less than 15, as the fuse for the fuel pump is 15 Amps.
Monday I bypassed the relay with a paper clip, it started. So we pulled the same relay from the parking lights and it fired up and ran perfect. He went to Autozone and got a relay and popped it in there.
Tuesday, when he plans to head home, that Autozone relay had failed. Now, I did some research and apparently the original relays on this particular automobile had issues which led people to spend hundreds of dollars replacing the fuel pump to be stuck with the same problem. So, again, we stole another relay from the AC and started his car for the journey home.
Wednesday(today), we planned, after the research on Tuesday, to buy new relays from the dealership, hoping they were different and more superior. They were different, but unsure as to the superiority until tomorrow. There are six of these types of relays in his car. As I had swapped a bunch out, and some worked and some didn't, we put a new one in the fuel pump, and put an old one in the AC, which worked. The rest, which I have, I am going to test tonight.
I have read that on newer vehicles, the fuel pump relay powers the fuel pump during start up. Once oil pressure is achieved, the oil pressure sending unit powers the fuel pump. This is so if there is a wreck, the engine cuts off, as does oil pressure, and therefor kills the fuel pump so fuel isn't possibly spilled through a busted line.
Now I am wondering, if this is true, are there (2) circuits that control the fuel pump relay? I ask because, if I put a paper clip in the 87 and 30 socket, start the car, it will run until I pull the paper clip out. So this means (1) of (2) things, this vehicle does not have that feature, or the 12V low amperage control signal comes from two places. Does anyone know anything of this?
Also, what are other reasons for relays to fail? Like I said, I am going to test them tonight. Amperage overload of the coil side? Control side? Corrosion? Time?
Monday I bypassed the relay with a paper clip, it started. So we pulled the same relay from the parking lights and it fired up and ran perfect. He went to Autozone and got a relay and popped it in there.
Tuesday, when he plans to head home, that Autozone relay had failed. Now, I did some research and apparently the original relays on this particular automobile had issues which led people to spend hundreds of dollars replacing the fuel pump to be stuck with the same problem. So, again, we stole another relay from the AC and started his car for the journey home.
Wednesday(today), we planned, after the research on Tuesday, to buy new relays from the dealership, hoping they were different and more superior. They were different, but unsure as to the superiority until tomorrow. There are six of these types of relays in his car. As I had swapped a bunch out, and some worked and some didn't, we put a new one in the fuel pump, and put an old one in the AC, which worked. The rest, which I have, I am going to test tonight.
I have read that on newer vehicles, the fuel pump relay powers the fuel pump during start up. Once oil pressure is achieved, the oil pressure sending unit powers the fuel pump. This is so if there is a wreck, the engine cuts off, as does oil pressure, and therefor kills the fuel pump so fuel isn't possibly spilled through a busted line.
Now I am wondering, if this is true, are there (2) circuits that control the fuel pump relay? I ask because, if I put a paper clip in the 87 and 30 socket, start the car, it will run until I pull the paper clip out. So this means (1) of (2) things, this vehicle does not have that feature, or the 12V low amperage control signal comes from two places. Does anyone know anything of this?
Also, what are other reasons for relays to fail? Like I said, I am going to test them tonight. Amperage overload of the coil side? Control side? Corrosion? Time?
