94 E320 Fuel pump problem.

[alexlepro]

I have a 94 E320 and when I first bought the car, the fuel pump was really noisy, making a loud hissing noise constantly when the car was on. I thought it was the fuel pump going bad so I replaced it with a new used one from a junk yard. The new one makes the same hissing sound, althought it is much quieter, it is still loud enought to hear inside the car when the windows are open and I would like to fix this. Is it normal for all of these pump to make this noise or should I look into a brand new one?

[Arthur Dalton]

Check the fuel filter.
A partially plugged filter puts a strain on the pump...

[Glen]

Interesting, my '95 E320 wagon just started doing this a week and a half ago. It doesn't happen constantly, but every few days I notice the fuel pump sounds like it's having to work harder by being noticably loud. During these episodes the car exibits a very interesting behavior. It drives fine except when making right turns. After a right turn if I get on the accelerator more than ~30%, the engine stumbles for a few seconds then clears up. Later in the day, on subsequent restarts the fuel pump is silent again and does not exibit the stumbling problem at all.

I ordered a new fuel filter and will be changing it out tomorrow. Hope that takes care of it.

[Glen]

I changed the filter last Saturday and the car is running great. Fuel pump has remained quiet and the car is running great.