After driving for an hour when I slow down and the driving noise is reduced I can hear a humming noise coming from the rear of the car. Is there a fuel pump back there that could be doing this?
Yes, most likely your fuel pump. My Merc has twin fuel pumps which are as noisy as hell even from cold and have been like that for years. Of course, when they are hot its even worse. When I eventually have them replaced I will have it converted to a single pump system.
When they are about to quit they get really loud. Unfortunately (or fortunately depending on your perspective) it could take years for it to actually quit on you. It will usually take out the fuel pump relay first though.
and best hope it's the one on the outside of the tank!
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Scott in MD/DC
94 E320 Wagon (Just getting broken in)
95 C280 (RIP)
87 190E (Sold)
"There is nothing more expensive than a cheap Mercedes"
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