300e won't start after replacing fuel pump
 

hi, i was given a 300e 1987 last week, after replacing the battery it will start and quickly shut off again. Found out that the fuel pump wasn't working and after replacing it now the car doesn't start anymore. After some test we noticed that the spark plugs are over shocking(:confused:not a mechanic so doesn't know if that is the correct term) with fuel. Any help will be appreciated.:o

Test for power at the fuel pump first. With the key on, it should give a reading for a bit.
If you have power, and the pumps run, then there is no fuel getting to the engine.

If no power, check fuel pump relay.



I have never heard of "over sparking"

thanks, fuel pump its working we think is sending to much fuel to engine, any clues how to regulate it?

Before the old pump failed, was someone messing with the fuel mixture?

Replacing the pump (AND FILTER) on my 190E totally changed the behavior of the car. I had to lean it down a good bit.

Maybe your fuel pressure regulator is not doing its thing?

You are SURE that you have spark?

fuel mixture? lost me there... it is starting up it just that it chokes on fuel and won't stay on... i guess.. i will check the fuel pressure regulator once i find it. thanks

When you turn the key, the fuel pump kicks for a moment to build fuel pressure. Turn the key to start, and it starts up. Again, are you sure you have spark after that little jolt to start the car? Wet plugs usually means no spark.

Pressure regulator is right there beside the fuel distributor.

If you havent bought one yet, I really suggest you buy a Haynes manual, or even better, a CD of your car's original service manual. Learning German-English will help you, too.

The fuel pump should not be able to send too much fuel to the engine. It pressurizes fuel at start and then after the car starts. It supplies a constant fuel pressure while running. If you have a bad fuel pump relay it may turn off right after it starts due to a thermal short. It is located behind the battery, behind the removable plastic wall. Take it out and re seat it and try again.