Fuel pump wiring / ECU not cutting pump
Discussion
Main issue seems to be the wiring from the bulkhead relay to the fuel pump (well to the other fuel pump relay, as I have the mod). After a bit of scouting I found the connector which attaches the fuel pump wire to the loom had burnt out. I undid the connector and spliced in two test wires before it and ran these over the car to the fuel pump. Nothing.
I then took the positive test wire and put it in 87 of the bulkhead relay and left the negative test wire still spliced to the negative loom wire. The pump now works, but does not shut off after it’s primed. The same happens if you remove the negative wire spliced and run it to ground.
The noble wiring is a mess, I guess white wires were on ½ price when they built the car.
I would have thought that the wire returning from the pump via the bulkhead would just go to ground as the ECU only controls 85 and 86 of the bulkhead relay. Is that right?
So why is the ECU not cutting the power to the bulkhead 87 relay pin and keeping the connection closed?
I then took the positive test wire and put it in 87 of the bulkhead relay and left the negative test wire still spliced to the negative loom wire. The pump now works, but does not shut off after it’s primed. The same happens if you remove the negative wire spliced and run it to ground.
The noble wiring is a mess, I guess white wires were on ½ price when they built the car.
I would have thought that the wire returning from the pump via the bulkhead would just go to ground as the ECU only controls 85 and 86 of the bulkhead relay. Is that right?
So why is the ECU not cutting the power to the bulkhead 87 relay pin and keeping the connection closed?
Is it the original Relay? It may have the contacts "welded" together now!
( relay contacts suffer from pitting, which increases there electrical resistance. In high current applications, like driving a fuel pump that can pull 15Amps, this causes the contacts to overheat, which eventually results in them melting together!)
(you can often "pop the lid off" relays and take a look at the contacts to see if they are damaged!)
( relay contacts suffer from pitting, which increases there electrical resistance. In high current applications, like driving a fuel pump that can pull 15Amps, this causes the contacts to overheat, which eventually results in them melting together!)
(you can often "pop the lid off" relays and take a look at the contacts to see if they are damaged!)
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