LS swap on an 87 TBI

[Steve87GMC]

I’m most of the way finished with swapping an ls3/6l80 into my 87 GMC R1500. My question is what wire is the factory fuel pump feed ? I have eliminated the fuel pump relay and all of the factory harness. There is a tan/white wire coming up to the firewall from the harness that goes to the tanks I haven’t had a chance to test it yet but I am assuming this was the feed to the pumps ? I am retaining my dual tanks and switch.

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[hip2bsquare]

the signal wire needs to go to a powered relay to supply power to the tank switch in the dash. on my 2013 the (pinout) wire diagram for the ECM indicated what wire that was. then from that point I just did everything the way the factory (in my case 1986 truck) wiring and line routing/connections. Being a '87 the dash switch is made to handle the power and switch it accordingly.

good luck!