Damn, it's the fuel pump isn't it!

[TheJacket]

OK, high pitch whine going on behind the back seat of my 280SEL 4.5 liter ('73) - changes in pitch a bit, fades in and out, and continues for 30 seconds after I shut off the car.

It's the fuel pump isn't it? Any cures other than replacing it?

Thanks again, gang....

[Peoria Benz]

Hey there! I posted a thread recently about noise from back there which only seems to occur after I turn the motor off when things are warm. I haven't had a chance to see if it is the pump or some pressure release from the return line from the fuel rail. Just curious, how does your car start when hot? Does your noise seem to be there even when running? Or with key in the second position, but motor not running? We'll get it figured out yet. Maybe with the three day weekend.

[TheJacket]

Is yours a high pitch whine? Haven't checked to see if it starts before I fire up the car (which seems to start just fine under any circumstances), and yes, it makes that sound while I am driving - again, changing a bit in pitch, etc, but there.

Part II of this is that if it IS the fuel pump, and I do have to replace it, I am seeing around $500.00 online EXCEPT one place that calls it an "In-line" fuel pump and it's $67.00...WTF?

[Peoria Benz]

All of the 6 cylinder mechanical injected cars I have ever owned have a fuel pump you could hear, but I have never really noticed it with the elec injected V8. The "run on" whine is fairly high pitched and as of yet, I have not been able to isolate it. (wife gets mad when I get my good trousers dirty) As far as the price, the $500 range sounds right. The cheap one has to be the wrong part.

[jireman]

Originally Posted by TheJacket

OK, high pitch whine going on behind the back seat of my 280SEL 4.5 liter ('73) - changes in pitch a bit, fades in and out, and continues for 30 seconds after I shut off the car.

It's the fuel pump isn't it? Any cures other than replacing it?

Thanks again, gang....

have a pump of my 76 450 sl car is getting a 302 ford engine if I ever get started Jim In Omaha 402 453 7889

[TheJacket]

Well, whatever it was, the noise has stopped...I wonder if it had anything to do with trying a much lower octane gas ...now that I have run higher octane thru it, the high pitch whine is gone.