E320 (W210) Intermittent Starting Problem
 

I'm having intermittent problems with my E320 cranking but not starting. It has also stalled twice, once at a stoplight and once in a slow turn. No check engine lights.

The pattern I've observed is that it starts fine when it is cold, but after it has been driven for a while (e.g. 10 mi), it will not start again unless it cools down for at least a couple hours. When I drive it, it runs smooth, with the exception of the two stalls. But then again, I let it sit for a few hours and then it starts fine.

The first thing I tried was a new fuel pump relay, but that didn't make a difference.

Any ideas?

Have you replaced your fuel filter? Mercedes recommends replacing the fuel filter and air filter at 60K miles. They also recommend replacing the spark plugs at 4 years or 100K miles (which ever comes first).

The fuel filter for this car is not cheap - it has a built in fuel regulator.

The fuel filter was replaced about a month ago when I did the 60K service. The spark plugs are on my to-do list.

Update:

Problem solved. Took it to my mechanic and he replaced a knock sensor.

Where is the fuel pump relay located on W210, I have 97 e320

Thank you

The relay is in the fuse box beside the battery, underneath the rear seat. MB part number 02 542 13 19.

benzthere

Thank you very much