No power to fuel pump circuit. not relay, ecu or ign. switch what else?

[mattd]

I have ruled out/ replaced ignition switch, main relay, ECU,fuel pump relay, fuel pump resistor. I have isolated the problem to a dead black w/yellow stripe wire on the right side of the main relay. This is an intermitent problem, leads me to believe a broken wire. I have been running with a positive jumper to this blk/yellow wire and everything works as normal. At first when the intermitent problem would appear in the past, I would place a positive jumper directly to the fuel pump to limp home. I noticed that when the circuit would go bad, the speedo did not work and there was no charge from altnernator but no battery light on dash. Does anybody have an idea where this wire (black w/yellow stripe)would be losing continuity?

I noticed that when the circuit would go bad, the speedo did not work and there was no charge from altnernator but no battery light on dash.

 

[hlweyl]

Hello, although I don't have a good answer to your problem. I'm 99% sure that prime member "Larry Bastanza" had a similiar problem where everything indicated main relay problem but ended up being an electrical gremlin on the relay connection itself.

good luck

 

[TigerNSX]

A very silly question. Is your battery old or is it one of those lightweight batteries with very low power?

 

[Larry Bastanza]

Actually mine was a bad conector for the fuel pump resistor. However it sure seems like you have done 99% of the investigation already. Now you need to follow this wire to find the bad connection. I think you should also check where this wire may be fused. Since interconnects are highly suspect, I would go there first, then follow the wire from one end to the other. I know it is easier said then done, but that is where you are at now.

HTH,
LarryB