E320 (W210) Intermittent Starting Problem

[benzthere]

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?

[Southern]

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.

[benzthere]

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

[benzthere]

Update:

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

[MarekW]

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

Thank you

[benzthere]

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

[MarekW]

benzthere

Thank you very much