This 1993 LS400 has an issue with the fuel pump periodically not getting the voltage to run. I have been able to jump the +B to the FP pins in the Data Link 1 box on top of the engine. Usually, this will run the fuel pump but as the weather cools this too has become unreliable. I can run a wire directly from the battery to the DL1 FP pin hole but that runs the fuel pump even when the key is off. I feel there is a short in some part of the harness but have problems finding it. Any ideas to fix this problem?

 

sounds like a resistance issue to me

 

Is it throwing any codes? In the old days I'd say get a new FP but this may involve other issues.

 

It sounds like it's time to change the FP & the FP relay.