TheSamba.com :: View topic - Crank-no start: Fuel Pump Relay wiring corrosion

Tue May 13, 2025 3:36 am

1986 westy with 2.1L:

After driving fine to work, wouldn't start an hour later when I was in a rush to get ready for Mother's Day dinner. Would crank strong but nothing else. I looked at dist cap and rotor, which looked OK. Listened for fuel pump - nothing! Went to FP relay and pulled it out. Looked like this:

Well that's not good. Swapped with ECU relay and voila, vroom, vroom. Looked under the relay box and found this:

The dreaded copper oxide. OK, so I got back on the road and made it home to cook Mother's Day dinner, which was priority #1. It is clear what needs to be cleaned up, but my question is "Why that one pin?" It was the 86 pin on the relay, with a red/brown wire. I believe that goes to current track 15. All the other pins look perfectly fine on the relay, and on the wiring below. Discuss please.

PS: Thanks for everyone over the years that has posted troubleshooting solutions here. I read them all the time and have slowly but surely gathered enough knowledge/experience to be able to sometimes solve these problems myself, which is a great feeling.

Tue May 13, 2025 6:16 am

At some point in the past you angered the Electrical Corrosion GOD... :wink: :wink:

No idea why that one wire. Contact cleaner spray if the pin isn't too bad and can be saved, or a new pin if it is too far gone.
Relay I'd save as a spare once cleaned up.
De-oxit or similar anti corrosion paste smeared on the pins once you're all done to help prevent this in the future..

Tue May 13, 2025 6:18 am

what a great puzzler! here's some conjecture....

first, some observations:
- the blade on the relay appears to have had the tin plating over the copper eroded away, pretty strong galvanic reaction. supported by the green oxidized female connector. i *believe* the female connector is copper beryllium. strong and quite corrosion resistant, until it's not. strong evil force at work.

- pins 85 and 86 power the relay coil. 86 goes to a 12v supply, 85 to the ECU where the ground for the fuel pump relay is controlled. very low current draw when active, no heating would occur to destroy the integrity of the spade and connector.

the WAG part.... Wild Ass Guessing
- those relays do not look OE, am i seeing a mounting tab on them? one thought is that who ever swapped the relays in place had a drop of salty sweat roll off the end of their nose and drop into that location. electrolyte provided for corrosion. doesn't even need to be sweat drop, could just be finger sweat.

- again assuming not OE relays, the factory could have left a bit of acid residue from manufacturing the coil that wicked down the blade into the relay socket. or SOMETHING off-gassing/leaking out of the relay to start that corrosion. it would be interesting to pop the cover off the relay and see if there are any clues.

Tue May 13, 2025 8:14 am

Thanks guys. Yes, they are not original relays. I did hit the relay AND the receptacle with electronic contact cleaner but am planning on removing that wire and redoing the end. I have extra relays so I will probably put in a new one and if I can get that one open, I will update.