I'm swapping in 1987 TPI into my 1988. I've wired the tan/white wire coming out of the c100 connector to the tan/white wire on the fuel pump relay. The fuel pump kicks on when you turn the key to run, and shuts off when you turn the key to off. The fuel pump does not shut off after a few seconds like it should though. I can hear the relay click after a few seconds, but the pump continues to run. Also, if I disconnect the fuel pump relay, the pump still runs.

Anyone have any ideas to fix this?

 

Hmmmm, trying to remember. How about the oil pressure switch sticking?

 

I can try unplugging the oil pressure switch tomorrow. Is there a fuel pressure switch at all? I don't believe there is, but I do still have the tbi pump in there, so it maxes out at 15 psi.

 

Correct me if i am wrong but isn't the pump supposed to run as long as the ignition is on as the ecm feels the reference signal from the ignition module.

regards Mats

 

the ecm energizes the fuel pump circuit but there are safetys in line that will interrupt the current if something goes wrong.
if the f/p will not shut off it's most likely that the ops is stickey.

 

I unplugged the oil pressure switch and the pump still runs. Any ideas?

Looking at the wiring diagram, the tan/white wire that the fuel pump connects to is just spliced into the the MAF relay, Fuel pump switch, fuel pump relay, and ecm. So if any one of those relays work wouldn't the pump be getting power?

When I turn the key to run, the pump continuously runs, but after a few seconds (when the fuel pump relay kicks off) the pump changes pitch like it has less power available. This is with the OPS plugged in or unplugged.

 

You need to put a volt meter on the tan/white wire with the other lead going to ground. Sounds like your are getting some backfeed voltage on the tan/white wire. You will have to start disconnecting things until you find the source of the "unwanted" voltage. Do you have anything in the ALDL connector. Looks like if terminals D and A were connected somehow that would cause your problem.

 

Nothing is in the ALDL connector. Where should I be testing the tan/white wire? At the fuel pump relay? I'm not exactly sure how the fuel pump should be wired into this either.

 

Here is how it is currently wired. I'm not sure how the fuel pump is supposed to be wired in, here is how I have it.

 

Reference signal from dist only happens when engine is turning

Key on; the ECM runs pump for 2 sec to pressurise rail , then stops,
When cranking the OP switch closes @ 4 psi causing the pump to run and when the ECM to sees that the pump is running ( from pump voltage back to ECM on pump control wire shown in diagram ) and the reference signal from dist it powers up the pump relay again.
Should pump relay fail ,the OP switch will keep pump running or allow you to start engine once OP over 4psi cranking

 

same problem I have, dont know why. my lb9 didnt have a fuel pump feed wire at c100? really confused