Could a weak fuel pump cause fuel starvation to the point where the car actually vibrates when trying to accelerate? This has occurred sporadically when accelerating from 2000 rpm at 35-40 mph or so. I've assumed that the driveline was somehow out of balance. The fuel pump has been making a much more noticeable "whirring" noise when listening to it from outside at the right rear of the car. I listened to another c280 i have access to side by side and the fuel pump very quiet and hardly discernable. Impending pump doom and stranding? Of course, I will try to get it to my mechanic as soon as possible.

P.S. I switched out the fuel pressure regulator between the 2 cars and not much difference in my car, and none in the other.

Obvious question, but have you replaced the fuel filter recently? That can cause both pump noise and starvation you describe.

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Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz

Yes, just replaced 1000 miles ago. Changed every 30k prior to that.

Then it is probably the pump itself going bad. The only other thing that happens is over time the rubber shock-mounts that the pump assembly hangs from get brittle and do transmit more vibration to the car then when they are new. I usually just replace them as a matter of course when I replace a pump since they only cost a couple dollars and this way I can rest easy knowing I have done all I can do to quiet them and keep them hanging.

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Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz

I believe my fuel pump is the "in the gas tank" style?

I am pretty sure yours is like just about every other MB, mounted under the rear right fender area. There is a plastic cover held on by 3 screws and the pump and filter is under there...

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Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz

you're right

Good to hear...it's not too hard to replace them; just pinch off the fuel lines, cut off the old clamps, disconnect the wires, slip it out, slip the new on in, reconnect with new clamps and done. 30 minutes, tops.

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Marty D.

2013 C300 4Matic
1984 BMW 733i
2013 Lincoln MKz

Why couldn't GM make it that simple?

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1993 400E, 256,000 miles (totaled)
1994 E420, 200,000+ miles
1995 E420, 201,000 miles

The GM way is probably a lot cheaper.

Tom W

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[SIGPIC] Diesel loving autocrossing grandpa Architect. 08 Dodge 3/4 ton with Cummins & six speed; I have had about 35 benzes. I have a 39 Studebaker Coupe Express pickup in which I have had installed a 617 turbo and a five speed manual.[SIGPIC]

..I also have a 427 Cobra replica with an aluminum chassis.