How can I diagnose a Mercedes 300e problem with a fuel pump?

Answer by  Allstar (2071)

Sounds like you've got it diagnosed; usually if there's a problem with the fuel pump, you replace the fuel pump. While you're at it, you might replace the fuel filter, if it's old and clogged, it can put extra wear on the pump and reduce fuel pressure.

Answer by  James916 (539)

You need to disconnect the elctrical connector from the fuel pump. You should then install a test light to the connector and ground the other end. Turn over the ignition and if the light comes on, then your fuel pump is bad and you should replace it. But that part from NAPA or the dealer if it is bad.

Answer by  Atomicrayon (2504)

If you're seeing a significant reduction in miles per gallon then it's safe to assume that you're suffering from a lowsy fuel pump. As long as your car isn't visibly leaking gas it's the fuel pump in all likely hood.

Answer by  Oversite (18)

Assuming you have verified the obvious (i.e. battery voltage, fuses)you should start by verifying power supply to the pump. Should the supply be within accepted parameters check the (using an oscillascope) that the pump is function at peak performance. If all checks out as it should verify fuel pressure (required: Fuel pressure gauge)

Answer by  SpoonNZ (56)

You will need to establish whether it is the pump, the fuel lines, a relay, a fuse, or another issue. Relays and fuses are the easiest to start with.

Answer by  Srfingfreak (697)

Make sure that the pulley on the front is spinning. If you see fuel leaks at the hoses, you might just need to tighten them up a bit.

Answer by  JRossi17 (788)

Usually when you have a problem with your fuel pump your engine will be very sluggish. When you hit the gas you will not get as much power.