is this normal??

- E
- EBounds
  
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posted
20 years ago

Fri, Dec 12, 2003 5:09 PM

I am pretty clueless about vehicles so I wanted to throw this question out there for the experts. I just had the fuel pump replaced in my 1992 Buick Regal. Now I notice when I shut down the car and the car is cold you can still hear the fuel pump whirring for about 30 seconds, after the car warms up though its fine. Should I be concerned about this? One person did tell me its fine and that its probably just a cheap aftermarket fuel pump but I thought I would get other opinions.

thanks in advance

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- Indian Summer
  
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posted
20 years ago

Sat, Dec 13, 2003 4:19 AM

Indian Summer

Should I be concerned about this?

Yes. Sounds morbid but, someone plows into your car splitting the fuel line, too daze to get out, you cut the ignition with no luck.

Is the key out of the ignition?

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- CURLY
  
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posted
20 years ago

Sat, Dec 13, 2003 6:45 AM

Yes this is normal. Gm cars use an oil pressure switch as a back up to the fuel pump relay. If the relay should fail, then oil pressure will close the connnection and keep the fuel pump running. Cold engine oil is thicker than hot oil,so when you shut the engine off, the thicker oil is holding the fuel pump bypass switch closed until oil psi drops. After market pumps or factory, both will act the same.

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- Bruce Chang
  
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posted
20 years ago

Sat, Dec 13, 2003 8:39 AM

I'll precede this with, yes, the oil pressure sender is a back up for the fuel pump relay and no, the fuel pump is not the culprit, it is only doing what the fuel pump or oil pressure switch is telling it to do. So that being said.....

No, this is not normal. Go to any GM car lot and start any car and shut it down and see if the fuel pump keeps running. There is no reason the fuel pump should continue running after the engine has been shut down. If the thicker oil is holding the fuel pump bypass switch closed, then you have other problems than just the fuel pump running after shutting down. Most likely, your oil pressure sender is bad. I'd check it first. Or just unplug it and see if the whirring continues. A new oil pressure sender shouldn't be more than about $25 and since it doesn't sound like you'd do the work yourself, maybe 30 minutes of labor. Total cost: $50.

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- Garrett Fulton
  
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posted
20 years ago

Sat, Dec 13, 2003 3:43 PM

My '93 GM diesel pickup also does this and it is caused by thick cold oil holding the pressure switch closed. Won't do it with hot oil at all. There was a service bulletin about changing the combination oil press. transmitter/oil pressure switch due to the press. switch contacts building up high resistance and not allowing full voltage to the pump. This was the problem my truck had. There's an electrical schematic in the serv. bull. and batt. power is supplied to the press. switch/fuel pump circuit with the ign. switch turned off. Thick oil will hold the switch closed for about 10 seconds on my truck and keep the pump running after the engine is shut off cold.. I don't believe it's a problem at all.

Garrett Fulton