R107 Fuel pump relay failure again!!

[Bozzycyp]

Hi

Can anyone shed any light as to a likely cause as to why a replacement fuel pump relay for an 1983 280SL has also failed.

It may be a faulty part but im more concerned that there is an underlying problem causing it to fail. The car remained a non starter even when the new relay was fitted and now this part has failed.

Help appreciated.

 

[AMG19]

Only three things it could be - ignition switch, fuel pump or wiring.

 

[jaymanek]

the fuel relay has several safety features built in... you need to bridge the pins to rule out the relay... i think its pins 15& 47 or 30&47 (they should be directly opposite each other on the relay).

If bridging these pins makes the pump run continously and your car starts, you need to work out if its the relay thats broken or one of its several related items such as the OVP relay.

 

[AMG19]

What I would like to know is how do you know the relay has failed if when you put the new one in the car it still remained a non-starter?

 

[Druk]

the fuel relay has several safety features built in... you need to bridge the pins to rule out the relay... i think its pins 15& 47 or 30&47 (they should be directly opposite each other on the relay).

If bridging these pins makes the pump run continously and your car starts, you need to work out if its the relay thats broken or one of its several related items such as the OVP relay.

Pins 30 and 87. Wrap a wire between them and the pump should run with ignition.

 

[Bozzycyp]

Hi the pump used to run on the key then didn't. I bridged the pins and the pump ran. I then replaced the relay and the pump then ran on the key as it should. However I tried it again recently and there was no buzz from the pump. I removed the relay and bridged again with the pump now buzzing. I'm just wondering what has caused this second relay failure and if anyone else has experienced this?

 

[SilverSaloon]

hi

i just bridged these pins on the fuel relay of my 1985 107 as the pump wasnt working. I found that it made my pump run with the key out of the ignition....

anyway, i then took the relay back out again and removed the bridge and the car started and pump run as normal (buzz for a second when you switch on ignition). i guess it has a loose/dry solder joints.