Fuel injection pump wiring

[jpressick]

On the back of the fuel injection pump there are two posts with two wires attached.  One wire is green/red and the other is pink/black.  Anyone know which wire goes on the top post and which on the bottom post?  My car is a 250 SL which I bought brand new in Germany of November 1967.  Thanks Jim

[glennard]

One or two soleniod pump?

[jeffc280sl]

The MB wiring diagram show that each solenoid has a ground wire.

The second terminal of the fuel enrichment solenoid is connected to the fuel enrichment relay which is connected to the TTS and is part of the cold start system.

The second terminal of the fuel shut off solenoid is connected to a micro switch and is part of the emissions system.  In general the system and this solenoid shut off fuel to the FIP while coasting to reduce emissions.

You can use an ohm meter to determine which wire is ground.  It should not matter which terminal is ground or power feed.

[waqas]

quote:Originally posted by jeffc280sl

You can use an ohm meter to determine which wire is ground.  It should not matter which terminal is ground or power feed.

Won't the solenoid get magnetized in reverse if the leads are swapped? I imagine this would have a significant effect whenever the solenoid is supposed be in operation.

[jeffc280sl]

Solenoid current connections are not polarity sensitive unless they are specifically mechanically designed to connect with the engine block which must be negative in our cars.  I believe the terminals of our solenoids are designed to be electrically isolated from the FIP and therefore the chassis ground.

If the connection is polarity sensative I think MB would indicate this on the solenoid itself with a plus and negative mark.