1987 GMC V1500 TBI crank but no start

[NateP350]

I have an 87 GMC with a TBI 350 that has been sitting for about 15 years. I put a known good engine in it that came with a throttle body. I have replaced almost everything in the fuel system, tanks, fuel pumps, lines, filter, relay, tank selector valve and switch. I went to start it and it cranks fine but will not start. I replaced the distributor cap, rotor and ignition module. I have spark at the plugs. I noticed my fuel pump wasn't turning on with they key so I made a connector and got the pump to run and then I had fuel at the throttle body. What would cause my fule pump to not run. Or does someone have schematics so I could test the wiring harness. I open to any ideas at this point.

Thank you

 

[YakkoWarner]

Will it run if you manually power the fuel pump to get fuel to the throttle body?

The pump is controlled by a relay with an oil pressure switch backup (relay should be up on the firewall). There are a lot of good wiring diagrams available right here on this site - just goto FORUMS at the top and look in Squarebody Reference Library. Pretty much everything to know about the fuel pump wiring will be in there....