Chuck, I did the following test you have given me and here are the results:

0. Pull the relay out.

1. Test pin 11 for ground. - GOOD ground

2. With key ON, test pin 8 for 12V - GOOD, 12V Present

3. Jump pins 7 and 8 on the socket with a piece of #12 wire. Pump should run. If it doesn't then it's most likely a wiring problem between the relay and the pump. Be sure you have ground at the pump. - GOOD, Pump is running

4. Put a meter or test lamp between 11 and 12, and see if you have current when you crank the starter. If no current, fix the wiring problem - I believe 12 gets current from the purple wire that runs from the big connector on the right fender well (where the batter is connected). - GOOD, lamp lights up when starter is turning


Seem its a relay problem. Chuck, I also have a 1980 450SLC. My question is, can I use the relay of my 1980 450SLC and put it in my 1985 380SL just to test if it is really a fuel pump relay issue? Is there any other thing I can do to run the car without a relay with the use of a jumper? Please advise if not I will just order the relay. Regards.