fuel pump not running when key is turned

[mobzs]

hi every one,

i have a 4.3l, fuel injected, 93 s10 blazer. on my way to work yesterday i stopped at a store. when i got back in to leave, my truck wouldn't start. got out and didn't hear the pump running (mine runs all the time)
i never had a single problem starting it, one turn of the key and it's right there running. after some road side troubleshooting i ended up jumping a wire from the fuse box to the pump connector directly to get it to run.
today, i figured out that the relay is good, all the fuses are good, the wire to the pump is good, the ground from the relay is good, and i have power to the relay. what i don't have is a signal voltage to the coil side of the relay from the ecm/pcm. my question is does the ecm look for something before it gives a signal to the relay or is automatic when the key is turned? any questions just ask.

thanks
mobzs

[tom3]

Believe the ECM does turn it on. Gives a a timed shot before starting, then when it gets an RPM signal it turns it back on and keeps it running. Not sure if the 93 has a backup with an oil pressure sender or not though. Passkey, if you have it, shouldn't affect it either I think.

[mobzs]

yes there is an oil press switch on the 93. i'm thinking i my have a faulty ecm.