W140 Fuel Pump problem - relay or pump?
 

My '95 S500 developed an interesting problem... it has done this 3 times in teh past 2 weeks. Start the car, it runs for 4-5 seconds, then dies. After restarting 8-10 times, it runs and everything's OK.

I tried the door lock trick, but no avail. Besides, it does start, then dies.

I can hear the priming pump run - I surmise that's what's getting the car started in the first place. However, because the car runs for only a few seconds, it seems the main pump is not working. I guess it's burning up all the fuel from the initial pressurization.

I've had starter motors develop "dead spots" on the armature where they won't turn in a certain position. Could this be the problem with the fuel pump?

Or is there a relay that may be intermittant?

If so, where would said relay be located so I may test it?

Thanks in advance....

- Kevin

Posting fix...
 

This problem was sloved by inserting a /5mm thick shim between the crankshaft position sensor and the housing to space the sensor farther away from the crank. Learned of this TSB on AlldataDIY site... the car's been fine since.