When my fuel tank is nearing empty, I can hear noises coming from the back of the car. The best way I can describe it is like a groan for 2-3 seconds, and audible above all the other noises in suburban driving. It repeats at variable times from 10 seconds to 2 minutes.

Today, for the first time, I noticed it after I had switched off and locked the car. I could hear it 30-40 feet away, and then it stopped.

So I started the car again and listened for it underneath, near the fuel pumps and accumulator. Nope. Not from there. Opening the boot/trunk I found it was loudest on the left side hidden in front of the panel covering the fuel tank. I then removed the fuel cap and let the pressure escape - the noise stopped.

Is there some sort of pressure relief valve hidden behind there? The fuel check valve? How do I remove the panel to check it out?

Also, my fuel pumps are quite noisy, and the buzzing noise is audible all the time while driving. One has a nasty noise like a little ball bearing being crunched every now and again. Sounds like replacement time. I have yet to change the fuel filter, and reading this forum I should probably expect some improvement if it is clogged. With new pumps, should I expect them to be inaudible in the cabin while idling/driving, and will the car still run if one pump fails?

Any ideas would be greatly appreciated.

__________________
Steve

1982 380SL

Previous cars of interest
1981 500SE
1976 Jaguar XJS
1974 Rover 3500
1953 Riley (before they became scarce)

it certainly would be worth your while changing the fuel filter if it is due for a change as per the maintenance schedule.

my car had an intermittent noisy fuel pump which would buzz,hiss and groin at times, it was driving me nuts,so i replaced it with a new bosch one from the dealer, and the car is now a dream to drive,no more irritating noises and a quiet ride as it is supposed to be.

fastlane do sell bosch pumps on this website.