Okay. Lets start with a description of how the system works and then go backwards. When the engine is cranked, current flows from terminal ST2 of the ignition switch into the ST (starter) relay coil and current also flows into terminal STA of the ECM (STA signal).
When the STA and NE signals are received by the ECM, Tr (power transistor) is switched on, allowing current to flow into the circuit opening relay coil. The circuit opening relay switches on, power is supplied to the fuel pump and the fuel pump operates.
First, check and confirm there is a ground, and also let me know the colors of the other wires in the harness. When I look at OEM schematics, they are very difficult to follow. If you look at the one I sent, it doesn't even indicate a yellow wire.
I also need to know this. You get power to the yellow wire when the key is turned on. Does it only power for a short time? Also, are you sure the pump is good?
May 21, 2021 at 5:56 PM