need help with fuel pump with 5.0/c4 conversion

[dbrannan]

Hi, my friend and i have been converting his 1994 mazda b3000 with a 5 speed over to a carbureted 5.0/c4 combo. we got everything hooked up and spinning over, only to find out his fuel pump wasn't coming on. we did find information on the clutch pedal switch and tried to bypass that to no avail. also, we bypassed the fuel pump relay, 30 and 87 and still won't kick on his pump. He pulled the pump and tested it against a battery and works fine. Is there part of the ecm or something were missing preventing it from getting power to the fuel pumps? he also checked the inertia switch, so we are at a loss. any ideas?

 

[adsm08]

The computer runs the pump, primes it when the key is turned on and then leaves it off until it sees engine speed above 300 RPM. Even if you still have the computer present you probably don't have the crank signal telling the computer to kick the pump on.

But if you went carb then why not use a mechanical pump?

 

[dbrannan]

i personally would have went a different route, but he wanted to regulate the existing fuel pump down to his carb. I think he's going to run a relay seperate of the wiring harness to power the pump if we cant figure it out