Fuel pump relay bypass

[Lapponia]

Nolan197,
You are very close to a working "new" DME relay but I think a few changes in circuits are needed in my humble opinion.
I have this setup in working order for more than a year now but it has some differencies from your circuits. May I suggest the following:

1. Change diode to 1N4001 (50V, 1 Amp).
2. Let lug 85 on left side relay go direct to ground. Remove wire from same lug to pin 20 on DME.
3. Remove direct ground from lug 85 on right side relay.
4. Fit a new wire from lug 85 on right side relay to go to pin 20 on DME.
Optional: Replace wire between lug 87 on left side relay and lug 86 on right side relay with a diode (1N4001 as above). Cathode (silver ring) connects to lug 86 on right side relay.
Rem: For a more rigid construction, use double relay socket and make all wiring from there including the diodes. Let wires be finished with suitable flat crimp connectors (2 sizes) to be connected in the original DME socket. Fix wires with zip ties.
Good luck
Lapponia

[Nolan197]

I'll take a look at making changes I am using a dual relay holding in the actual set up. I'm gonna wire up a second one in class next week so I'll make it using your suggestions and test it out.

[Lapponia]

Nolan 197
Please do the changes in your latest drawing and put it here. I will be happy to look at the new cirquits to compare them with my own which I know is working.
Lapponia

[MarcoPau]

Hi everyone, trying to bypass in order to check my fuel pump. My 82 SC (USA) shows 2 relays inside the cover being connected to the fuel pump.

I only have one of those two sockets there, and noticed there's a loose squadre relay around close to the relays box (Bay e some old modifications?)

I can hear the relay click if I unplug/plug it in with key on, anyway tried to bypass #30 and #87a with a loose wire and cant hear any pump revving.

Guess I'd better remove the panel under the car and check the pump directly or is it possible to avoid such operation?

Thanks everyone!

[911tracker85]

when helping a friend resurrect his 84 944 I wired up a bypass switch to get the car running. at the time seemed like a combination of bad ign switch and bad DME. but the wiring is a big mess under the dash and in the console. we're in the middle of a TB/WP/etc job, and will then go back to the wiring. also found the driver's side headlight not working and from limited troubleshooting seems it is also something in the fuse panel/wiring under the dash.

[MarcoPau]

I took away the panel covering the fuel pump and brought direct 12V to it. It's revving, luckily.

I have tried to also bring direct 12V from the battery to the socket pin but that won't work. I guess I am either missing something, or there's a fault in my electric system.

It looks like the + wire of the pump is a black wire: does this mean I will be able to find that wire around the fuse box in order to give direct 12V to it and try turning on the car?

Thanks again!