I have a 1999 E320. Sometimes when I turn my car off and try to restart it, it will not start, it just cranks. If I let the car sit for two - three minutes it will usually start. Lately the car has died at stop signs, but will start again. Is this the fuel pump or the fuel filter? If so, where are they located and how do I get to them? The car only has 63,000 miles. Help!

 

My guess is a fuel filter problem, it would definately be where to start. Fuel pump seems too early to die.

 

Here's a DIY: If it asks for a username or password, PM me

 

That is what i thought. Do you know where the filter is located? Thank you for your quick response.

 

When i clicked on the DYI it asked me for a user name and password.

 

I would have started with the fuel pump relay due of the time taken for the cause to "cool" down or whatever.

The fuel filter is near the top of the list of possibilities due partly to the fact that it is a lot cheaper to replace. However I have never actually come across a "blocked" fuel filter and if it were the filter why would this NOT be picked up during heavy fuel usage eg high speed.
Debris sucked towards the filter element can however fall away once the flow drop off.
Choice is yours.

Suspect the pump will be fine.

Personally I would rig up some form of warning light circuit across the fuel pump supply terminals and await the next occurrence. I like to have 100% decided the cause BEFORE spending any money on parts that may still be OK.
If the light goes out then it is the power supply = fuel pump relay.
However if the light remains ON then it must be the pump or some form of blockage.

Other possibilities.
1. Is there any correlation to the fuel tank level when the problem occurs. i.e. 1/4 full or less in which case it could be associated with the fuel pick up in the tank.
2. Oil pressure is used to "latch" the fuel pump relay into the ON position. Could be the pressure switch or even poor oil pressure at idle. The relay is however temporarily held in the ON position during cranking by a separate supply so it looks more like the relay than the inputs to the relay.

 

Where is the fuel pump relay located. This is my first Mercedes to work on.

 

Is their a good repair manual like Chilton's that a person can buy?

 

The fuel pump relay is located in one of the "black boxes" at the rear of the engine compartment.
The FP relay is not a conventional square plug in type but a special MB box which covers multi functions including the auto start sequence that your V6 is fitted with.
These units are known to give trouble due to poor manufacturing control however this does not mean that this is definitely the cause of your problem.
As I stated I would first satisfy yourself that power is always available at the pump and especially during a period when you expoerience a problem starting.
The fuel pump is located under the rear floor adjacent to the tank. Not sure exacvtly where on your model but once you have the car on a ramp it will be self evident.
Stuart.

 

Replaced pump relay and filted but it did'nt fix the problem. The car starts and runs great it seems like until it warms up than it will just die. You have to wait for 5 min (no give here) than the car will start and run for a while again. If you come to a stop sign or slow cruise(10-20 mph) it will die. You have to wait 5 min again than it satrts again. Now if you are cruising on the highway it runs fine. The car is a one owner and has been babied (it's not a beater) and has` 60,000 on it. Any nextsteps