I have had absolutley no problems with my 300E for over a year now. yesterday I noticed that at barely costing speeds it would almost "buck" (the RPMs would fluctuate between 5 and 10).

I had just fueld up and thought perhaps there had been water in the gas so I added a bottle of dry gas at the next stop.

The dry gas has not fixed this challenmge and the gas mileage has gone from great to YOU GOT TO BE KIDDING ME!!!

I'm still thinking fuel, perhaps change the fuel filter?

What do you all think?


Dave H...

Bucking is usually starving for fuel. Try fuel filter first, but the fuel pump may not be putting out full fuel pressure. Dont forget you also have a strainer in the fuel tank that can become plugged.

__________________
1959 Gravely LI, 1963 Gravely L8, 1973 Gravely C12
1982 380SL
1978 450 SEL 6.9 euro restoration at 63% and climbing
1987 300 D
2005 CDI European Delivery
2006 CDI Handed down to daughter
2007 GL CDI. Wifes

Pull the vac line off the fuel pressure regulator and see if fuel is coming out that vac port. Should be None.

Well I got around to attempting to change the filter - $62.00 for a filter????

What does everyone use to free up rusted screws, bolts and/or nuts? WD30 will not put a dent in it.

Dave H...

I wouldn't think a blocked fool filter correlates with poor fuel mileage. But I was wrong once before.

I suggest the first thing you need to do is check for error codes from the engine management computer. You can do this by building Arthur Dalton's code reader - use the search feature to find instructions. You could be dealing with a failed MAF or O2 sensor and not even know it. The car will run on a limp-home program in these situations. Driveability is poor and fuel economy is low when running in limp mode - sounds rather like your complaints.

- JimY