I finally got the egr spacer and a carb for my 460 that I need to get it running...
It'll run on a prime, but, I am not getting fuel to the carb. As far as I can tell, the electric pumps are not running. I tried bypassing the oil pressure switch for the fuel system, and the solenoid on the firewall clicks and the tank selector works, but, still no fuel. I checked the inertia switch too. Is there something I am missing? The truck was running 3 months ago.
Evan
85 F250 HD XLT Lariat 4x4:
460/T19/NP 208(I think) 3.55 geared Full Floater 10.25 and a Dana 50 TTB
1982 F100 SWB
300 HD: NP 435/2.75 geared 9"
78 F150, 351M/C6, soon to be repowered with a 400

 

Get a test light or multi-meter and check for voltages. I believe the fuel pump has a seperate fusible link that feeds the fuel pump relay.

 

I dug out my boss's Motor manuals after I towed the truck to the shop at work, and, the wiring at the tank selector valve/switch does NOT match the diagrams... According to the diagram I have here, there should be a red wire from the selector to the front tank that gets battery + when the front tank is selected, and powers the fuel pump, on my truck, the red wire(may have had a yellow stripe) has battery power at all times and powers the selector. After that, I just gave up, I'm soon gonna pull the box off of it and see what I can do.
Would it be possible to scrap the electric tank setup, replace the pumps with the sender for an I-6 truck(I know they ran an engine mounted pump until they went EFI) and the selector with one for the same and just run a mechanical pump on the engine?
Evan
85 F250 HD XLT Lariat 4x4:
460/T19/NP 208(I think) 3.55 geared Full Floater 10.25 and a Dana 50 TTB
1982 F100 SWB
300 HD: NP 435/2.75 geared 9"
78 F150, 351M/C6, soon to be repowered with a 400

 

Hmm, I just noticed something, while the truck's build date is 09/85, according to the emissions decal it is an 86, that may make soeem difference in the harness, although the manual I have says that they should be the same.
Evan
86 F250 HD XLT Lariat 4x4:
460/T19/BW 1350 3.55 geared Full Floater 10.25 and Dana 50 TTB
1982 F100 SWB
300 HD: NP 435/2.75 geared 9"
78 F150, 351M/C6, soon to be repowered with a 400

 

I looked at my diagram and it looks like the pink/black wire is what feeds the fuel selector switch. This pink/black wire is fed from the starter motor connection to give fuel when the engine is cranking. This circuit has it's own fuse link(dark blue). The pink/black wire is also fed from the fuel pump relay circuit. The relay coil is powered from a oil pressure switch. The power for this pump circuit, is routed from another seperate fuse link, through the inertia switch, through the relay, through a .750 ohm resistor and then joins up with the pink/black wire that came from the starter. In other words, one circuit comes from the starter side of the starter solenoid, and the other comes from the battery side of the starter solenoid.

I can't make out exactly what's going on after the pink/black hits the fuel selector switch. I am going to guess that the red is front, and the brown/white is rear. It looks like the fuel selector switch directs the fuel pump power directly to the selected pump. You should be able to figure out what the pump wires are because they will be heavier guage. It looks like they are also tapping off the red and brown/white wires, and are using these to power a motorized selector valve. This valve must have contacts in it to switch the yellow/white wire(fuel guage) from the front sending unit to the rear sending unit, and I am also guessing it actually moves a spool valve which directs the gasoline to the proper fuel line.

This whole fuel pump system will not have any voltage unless the engine is cranking, or running, so to trouble shoot, I think I would find the beginning of the starter motor circuit, and make a jumper to power it. Then you can begin testing the circuit. You may also have to make a jumper for the relay circuit to trouble shoot it. It maybe as simple as a bad oil pressure switch.

 

I've got everything(including the oil pressure switch) bypassed so that the solenoid closes when I turn the key to the run position. Just for the heck of it, I took a gander at the fuel system wiring diagram for a 302 EFI truck, and, it matches my truck. I tried applying battery + to the brown/white stripe that doesn't go to the selector(positive lead for the front tank pump) and got nothing. The wiring is a bit odd, the brown/white goes from the tank selector switch in the dash to the pump and the selector solenoid/valve. I wasn't able to get in the shop at work today to get my voltmeter(didn't have my keys) so, I couldn't be sure if I was actually getting power to the pump or not. I'm going to have to drag it into the shop tomorrow evening and see what I can find.
Evan
86 F250 HD XLT Lariat 4x4:
460/T19/BW 13450 3.55 geared Full Floater 10.25 and Dana 50 TTB
1982 F100 SWB
300 HD: NP 435/2.75 geared 9"
78 F150, 351M/C6, soon to be repowered with a 400

 

Well, I pulled teh box, and, it's just as I suspected, power to both pumps, but, they don't run... Oh well, time to pick up a mechanical pump.
Evan
86 F250 HD XLT Lariat 4x4:
460/T19/BW 13450 3.55 geared Full Floater 10.25 and Dana 50 TTB
1982 F100 SWB
300 HD: NP 435/2.75 geared 9"
78 F150, 351M/C6, soon to be repowered with a 400