Bout the time I think I got it figured out----. Okay, fuel relay issues. Relay in black plastic holder is the fuel pump relay, beside it is the relay with red stripe, main relay. So far so good. What is the square (about 2 inches) box right beside the two relays? It has an orange wire coming from it like is being described for the ECU .I am getting power to the fuel pump relay, but something is preventing it from running. It was, and will if jumped. Main question is what is that box and what does it do?
Thanks

 

I think you're seeing the 'fuel interface unit'.

It takes information from the ECU regarding injector pulse width and translates it into something the trip computer can understand.

Cheers
DD

 

Thanks Doug, makes sense. The fuel pump had been working, and here in the last couple of days while I am figuring out the AAV and setting throttles, as was suggested, the fuel pump quit. Changed relay, and it worked, then didn't, then did ---. You get the idea. Is the ECU fuel issue one that presents intermittently? Sometimes I turn the key and get the 2 second pulse, sometimes not, and it seems to be getting worse.
Thanks

 

Look at ignition key wiring and see if connector looks like it has been hot. Sometimes intermittent pump issues could be old key connector. Happened on mine.

 

Jagfixer, is the key system relatively easy to access. Have not tore into the interior of this thing yet. Best to pull whole switch, or turn upside down?
Thanks

 

I don't see any reason why it *couldn't* be an intermittant fault. AFAIK it one of the 'dry solder joint' faults on the circuit board inside the ECU.

Cheers
DD

 

The actual switch....the electrical part....is mounted onto the back of the key/lock assembly and pulls off after removing a very tiny screw. If you remove the underdash trim panel you should be able to remove it. But you don't necessarily have to remove it to visually inspect it for signs of overheating.

Does gently jiggling the key or wiring cause any reaction? if so, that's an obvious clue.

Cheers
DD

 

For testing purposes ONLY.

Coming out of the fuel pump relay socket is bunch of wires. One is an Orange wire. This is the EARTH wire for that relay. That EARTH is ECU controlled, hence the timer we know about.

Splice into that wire, and earth the spliced wire.

This will/should have the pump work whenever the ign is ON, so CAREFUL please. If that sorts the fuel pump issue the ECU is at fault, as Doug mentioned, and it is getting more common.

Your year model SHOULD have what is known as a 16CU ECU, but may still have the older 6CU unit, as it is sort at the time of change?. The 6CU were a problem with that circuit. The later 16CU is not, so far. The 16CU is a direct plug and go if needed.

 

I went out this afternoon to fiddle with it, and the darn fuel pump ran for the 2 seconds with the key turned like it was supposed to -- three times in a row. Good grief, be broke or not, I hate intermittent problems. Question in this rant of course is the ECU prone to this type of intermittent issues for the fuel pump circuit?
Thanks

 

Yes.


Cheers
DD