UZZ31 fuel problem - Its a big one

[Biggo]

So we got a soarer in at work yesty, job was the fuel pump not working. After much dicking around we found the folowing

- No cranking signal to pump
- There is no 12v at the diagnostics plug so we cant scan it.
- All fuses look fine and tested

So all of us are stumped. My thinking is the CAS has packed up and its not sending a signal to the ecu. Would this be possible, im yet to hear of a toyota CAS blowing.

Also, why is there no 12v at the diag. plug? Are we doing it wrong?

[thechuckster]

by "no crank signal to pump" do you mean to the fuel pump ECU, to or from the circuit opening relay or "when cranking the fuel pump is 0v"?

the "no 12V at the diagnotic port" needs to be fixed first

Is the ECU getting power during cranking?

[stevevp]

V8 soarer fuel pump ecu failures are a well known problem - temporary resolution is usually to bridge B+ and FP on the engine diagnostic plug, this bypasses the fuel ecu and drives the pump directly off ignition.

[CrUZida]

+12v in the diagnostic port (+B), the FP ecu and the two +B pins on the ECU all get their voltage from the same source. - The EFI MAIN relay.

If this relay fails, or is not switched on, nothing will work.

It gets switched on by the ECU, when ever the ECU gets +12V ignition from a different source.

ie, key switch ecu on, ecu switches relay on, relay powers a lot of things.

The EFI MAIN relay is protected by the EFI fuse.