Tonight, and the past few days I've been going thru a big cluster F of wires, partially my own fault, partially this big discombobulated setup I have I call the k5ton.
I have a 87 suburban cab harness, 89 instrument cluster, and a 91 k5 engine bay harness.
I need the cable speedo for my th400 (it was in there when I got the truck) and I'm using holley efi to feed my 502 ci big block, so ECM and so forth in the k5 does nothing.
When I started back on this project, I tackled wiring first, threw my marine battery in, wired up the efi, Alt, starter, body, frame, and engine ground.
When I turned the key for the first time, the efi turned on, starter engages and rolls the motor over, I have headlights, taillights, turn signals, engine temp was pegged all the way over, oil pressure jumped to zero, voltage went to 11v, I had no fuel pump, no fuel gauge.
Tonight, I got the fuel pump working off the fuel pump relay under the hood. I used the EFI's fuel pump 12v trigger wire and tied it into the fuel pump relay's green/white wire. It now triggers the fuel pump when I cycle the key.
Next up was determining my fuel gauge situation, I checked resistance, no issues on the sweep of the float... So I couldn't figure out the issue... I started looking, and I found my issue... I guess somewhere between the crossover from a 91 engine bay harness and 87 cab harness, some of the wires flip flop around, and the cluster's main bulkhead has a different pinout as well...
Remembering that I had the k5's old cab harness, I dug it up, checked the pinout, sure enough it was different!
So for the last what seemed like 1,000,000 hours, I went thru each individual wire that goes to the bulkhead, placing it where it should be to make the gauge work correctly.
All that's left is the oil pressure signal wire.... I need to go under the hood, and get the oil pressure sensor plug, firstly extend it to over by the power steering Pump because thats where you screw in the sensor on the gen 6 bbc as I was told, and then, trace down the signal wire and tie it into the instrument panel.....
So, fingers crossed, tomorrow when I button all the electrical back up, I'll have engine temp working right, fuel gauge, and all that other stuff!!
Good times!!!!