This is in regards to my '89 IROC.

My dad first noticed this out when he was washing his car: he said that roughly every four minutes, he would hear a buzzing sound comming from the back of my car. I went out, waited for a few minutes, and eventually heard the same thing.

Then, just last night when I was standing by my door about to put the key in the lock, I heard the exact same sound. It's a buzzing/whirring sound which comes out of the backend of my car and lasts for about 8 or so seconds, then turns off. I can't think of what else would make that noise except for the fuel pump.

Any ideas why on earth this is happening?

 

Fuel pump relay is sticking. Probably needs replacing.

Quick test: Unplug the fuel pump relay. The relay is located against the firewall, driver side, towards the fender, should be a series of relays, including the fuel pump. The color of the wires for the FRP are orange, red, dk green/white, and black/white. I think there is one other color as well. Try unplugging this while the fuel pump is running when the car is off. It should stop.

 

Hey, thanks for the response Stekman.

I know what you're saying, but the only thing is that it's not actually "stuck" on... it primes for a few seconds every several minutes, then it shuts off again for a while.

 

this could be fun problem to nail down.
there are a few things that could cause that.
the ignition switch could be the problem although i feel that is unlikely.
the wire between the ECM & relay could be intermittently shorting, or an intermittent short to power from the fuel pump side of the relay.
with out pulling up a wiring diagram im not sure on this 1, but if the oil pressure switch has a always hot power wire going to it, the pressure switch could be the cause of it or a problem with it's wiring.
the ECM may be intermittently powering up, the ECM should power down about 10 seconds after the key has been turned off & then stay off.
i have seen them stay powered up & cause dead batteries. i have never seen a ECM power up by it's self & then turn back off, but it is possible. outside of swapping out the ECM about the only way to check it would be to hook a scanner up & see if it communicates when the fuel pump is running.

 

The power wire from the oil pressure switch is spliced into the power wire that comes from the relay to the pump. You could try unscrewing that next time the pump runs. it requires 4 psi pressure in order to "switch" on. However, if that is sticking, it too could cause the intermittent priming sessions.

 

That usually happens right after you turn the car off, so it's normal to have the fuel pump prime then.

It might be a place for you to start diagnosing...