no power at fuel pump 1971 W109 3.5

[werminghausen]

I have no power at the pump.
Fuse #4 is good. I checked for continuity.
Further upsteam I should have a pump relay....but I don't know how to find this one.
Is this a simple ice cube relay?
Can someone tell me how to jumper this relay to get the pump going?

[Tomguy]

Often the cause is corrosion on the single small cable on the (+) terminal at the battery (or that it's just come right off). If that's fine, you can get to the relay by pulling out the ECU mounting board. It's a pain in the you-know-what, so I would check that terminal first.

[sjefke]

Martin,

Here are links to a post I made a while ago with location of fuel pump relay

W111 3.5 fuel pump relay location

And here is a link of my saga to figure out my dead fuel pump.

W111 3.5 ECU-fuel pump relay switching experts needed!

Make sure you test for voltage before AND after the fuse, not just connectivity. Fuse may be fine, but connection could be bad too.

If you have no + voltage at all at the pump, problem is between fuse and pump. As far as I recall, the relay switches the GROUND connection, not the positive voltage connection that comes from fuse. Relay is triggered by the ECU.

My problem was ECU related at the end of the day. I crimped a full circle connector on a wire. Pushed the wire on the relay pin that goes to the fuel pump. Pulled the wire to a switch under the dash, and grounded the other side of the switch with a wire to some screw under the dash. If pump did not work, I flipped the switch "on" which meant I created a ground to the fuel pump. I still have the switch in place (always off though) because apart from the extra wire, it does do no harm to the system whatsoever and is some extra insurance in case ECU or something else starts acting up.

Good luck. I know the frustration...

Bert