Just finishing up a motor job on a 1976 little pickup. I am running into the dreaded oil sender fuel pump issue. Right now the pump will not turn on. New oil sender in and it was working. I was driving along and the truck stalled and no fuel in the filter. Now the oil light doesnt come on with the key (did before). I would rater bypass the electronic fuel pump and put a mechanical in. I know whats involved and it is easier for me to deal with that swap than figuring out what the hell is wrong in the oil sender, fuel relay, fuel pump.
Anyone ever do this? If so how do you disable the pump and on the mechanical pump there are 3 ports.. in and out and a return. I assume the return could go to the canister?

 

Hmmmm... sounds more like you have an issue with your ignition switch and/or wiring. When you turn the key into the "START" position, the oil pressure safety switch is bypassed and the fuel bowl will fill up. So, what should be happening is, it takes a while to crank (until the fuel bowl fills up), engine will start and then when you release the key to the "RUN" position, the fuel pump will shut off and the car will keep running until the fuel bowl is empty. This will happen over and over.

 

yes.. I sort of understand the process.. This is what is happening on this rig.. I turn the key to the accessory lights on position and it starts! yes, before the crank position. I swapped in a new ignition switch and it didnt fix it. So I assume it is the tumbler (Key metal cylinder thing). SO I installed a push button start and bypassed the key start. It worked. The truck drove for roughly 10 miles then all of sudden died.. No fuel in the filter, no oil light with the key turned and no start of course. I didnt check the pump by jumping the terminal because at the time I didnt have the wiring diagram to do it. I suspect the problem is in the wiring somewhere but I dont know

 

Yeah... something is very wrong.

Since replacing the switch did nothing, I guess it's safe to assume the switch was/is not the problem.
How did you get the car started without the switch all the way over to "START"?
After it started, how did the starter disengage and stop spinning?
No offense, just thinking out loud, but you did install an oil pressure switch and not an oil pressure sender, right?

Oh, i forgot to ask, did it all work correctly before your motor job?

 

I wired in a push start. Wired to the starter replacing the stock starter wire with a new wire to the push button and battery. Turn the key to accessory then push the button. Power to the starter cuts off when you release the button.
I think on these trucks the oil pressure sender is the oil pressure switch. Same thing I think? When I got the truck the oil light was not coming on at all. But the fuel pump was working with the key turned on. The previous owner jumpered two wires that come out of the fuel pump relay. I assume that jumper bypassed the oil pressure switch. Don’t know. I installed a new oil pressure switch and that got the oil light back on. After ten miles down the road it all went to hell. I think what I’ll do is run a keyed hot wire to the fuel pump and bypass the fuel pump relay. I don’t have a wiring diagram and I am not sure what colored wire is the fuel pump?
Then I suppose I’ll try to figure out why the oil light is not working. What a totally strange way they did this system