My 300E has issues
 

Hi,
I am newb here so please be patient with me. I bought my son his first car a 1988 300E that has only 105.000 miles on the gas engine. It ran great but recently he let the gas tank run very low and now it wont start. I have no spark at the distributor cap and no line voltage power at the coil. I tested the fuel pump relay and bridged fuel pump relay contacts #7+#8. The fuel pump ran OK the next step according to ALLDATA was to check for line voltage power at fuel pump relay contacts #9+ #11 with the ignition switch turned on. This is NOT OK there is no voltage. The next process is to repair the open circuit according to the wiring diagram. The ALLDATA online logic diagrams are very difficult to read clearly the terminal numbers etc. I need some help deciphering what the next step is.

DDCGUY

As far as I know, ignition switch is the only thing between the battery and pin 9 on the fuel pump relay. The OVP relay can also bring this pin down to a low voltage. Remove the OVP relay and see if you get battery voltage on pin 9. If you get the voltage back, it can be either a bad OVP relay or you have a voltage higher than acceptable level, i.e. a possible bad alternator or bad voltage regulator. If you dont get approx 12V after OVP relay is removed, you have a bad ignition switch or a broken cable from switch to the fuel pump relay socket.

Bingo
 

Thank you Saumil it was indeed the ignition switch. Upon visual inspection of the switch it appears someone had done a poor repair job recently. KUDOS!!


DDCGUY:)