I have a 1983 Ford F-250 with a 460 and dual tanks. As soon as I bought it, it spun a rod bearing, resulting in a broken piston and I had to rebuild it.

The rebuild went smooth enough and the motor is back in the truck. Once I went to start it, I had a problem. I only got sufficient fuel to run the truck for 20 to 30 seconds before it would stall, from a lack of fuel.

Specs:
1983 F-250
Electric Fuel Pumps (in the tanks)
Two tanks (front/rear)
Tank select switch mounted to frame in front of front tank
Holley 4180C 4 barrel Carb
2 relays in the wiring harness on drivers side fender well under the hood. (Should there be two?)

I rebuilt the carb, thinking it may be a front bowl issue. It wasn't. I checked the fuel pumps and did not hear either of them. I went looking into the power lines for the pumps and found them connected to the starter side of the cylaniod. This provided power to the fuel pumps, but only when the starter was being turned, so the truck only got fuel when the truck was being started.

I have worked out a couple of work arounds at this point but I want to know what is the "correct" way for this to work:

I can move the cylanoid wire to the battery connect side, but the fuel pump selected on the dash then runs constantly. This is obviously not a good solution.

I can connect the power wire to an ignition hot wire under the hood, essentially direct wiring one of the two fuel pumps. The fuel pump will then run constantly whenever the ignition is on.

Major questions:
1. Should the power line for the fuel pumps be on the battery or the starter side of the cylinoid?
2. Should the pumps run constantly, or is there a cut off for them? Is this part of a "hot fuel return system"
3. What actual should/would do the electrical cut off of the fuel pumps? Is it something in the relay? Or is the fuel pump suppost to continously run?

Thank you for the help, in advance. I think I should just rewire the whole fuel pump wiring harness, but I'm not sure what the "correct" wiring diagram would be.

Tom

 

Get a Haynes manual - it shows exactly how to hook it up.

 

For this setup, Haynes manuals are of little help, been there, done that.
Your problem is that the fuel pump inertia switch is tripped out, or the oil pressure switch is toast. The inertia switch will be somewhere along the firewall inside the cab, likley behind the pedals, or on the transmisison tunnel. The oil pressure switch is on a T with the sending unit at the back of the intake.
Attached you will find the entire electric fuel pump section from my 84 Ford shop manuals(printed in Sept. 83, shouldn't have changed) I had to rotate them so I could upload 'em to my gallery, sorry 'bout that.
Evan

 

Evan,

Thank you. I've got a pretty good Chilton's Manual that I have about worn out in this engine rebuild. The wiring diagrams in the chilton's manual have done very little, however, in helping me figure out this one.

The pictures are great, but a little blurred by the conversion. Could I talk you into e-mailing them to me directly? If so, it is fordtruck@(REMOVETHIS)vsn1.com.

The (REMOVETHIS) is just so an automatic spider doesn't harvest my e-mail address and start sending me spam.

Thanks!
Tom

 

Hello, My 83 has the same problems as yours. It only runs for 20 sec. and it dies. What did you have to do to fix yours??? THanks, Dave.

 

Hi Tom, My 85 is doing the same thing. How did you fix yours?
Thanks,
Trent

 

Try jumping the wires at the oil pressure switch. If that fixes it the switch is the problem. If not start checking the relays.Could also be a pump or filter problem,Pump gets more voltage(= more pressure) on "start" then it does on run.

 

Okay folks, let me give my 2 cents worth. I went through this same problem on some later years F250's with both 5.0, 7.5 and carbed 5.8's (1985, 1986, 1987, 1989...all with EFI)> There are 2 systems that run the later fuel pumps and remember there are three fuel pumps. One inside each tank and the booster which is attached to the frame rail beneath the driver's side cab seat. All the ones I've seen have a fuel pump relay which is key activated so it runs in the start positon, Once the engine is running, the computer runs the power supply to the fuel puips. both fuel pumps must run in order for the engine to stay running. The inirtial switch will remove power to both circuits. The fuel pump control relay is located in the cab above the gas pedal and are commonly purchased from many auto parts store (NAPA). I can do some more research for you but I doubt very much if it's the iniertia switch because the truck wouldn't run at all due to no power to the fuel pump circuit. I assume this problem is present regardless of which tank is selected?

 

well actually my front tank doesn't even work. but my truck is carb'd, so would this all apply to my truck too?

 

The hot fuel system is just a hair different than an EFI one, mainly due to the lack of a computer.
There is no booster pump(rember, carbed, low pressure.) The fuel pump relay is out on the firewall, just below the drivers side hood hinge, and the Interia switch on my 86 was on the pass. side of the transmission hump, at the firewall.
The relay is powered through 2 circuts. Hot in start, which is hooked to the I terminal of the starter solenoid(these trucks MUST have a solenoid with 2 small terminals marked S and I) and is powered when cranking, and hot in run, which runs through the inertia switch and the oil pressure switch, and is powered with the key in the run position.
I'll re-scan my shop manual, if I can find it. I'd take pictures of my truck, but, that entire system has been replaced with a dash mounted toggle switch.

 

Okay, I did not know there was no booster pump (my bad). I did know there was a relay which is controlled by the inertia switch as well as the oil pressure switch. A simple test to see if the oil pressure circuit is fine is to jump out the power in and out on the relay (Usually the 2 biggest wires)> If everything works, then either the relay is bad or the triggering system is (oil pressure switch, wires going to oil pressure switch, or power to the oil pressure switch).

 

I checked and/or bypassed the two switches and had no effect different. So, is there a fuseable link that I could be missing??? I know im just not getting power to the fuel pump but it does work. Thanks, Dave.

 

you are not getting power on run but are on ignition (start)> Therefore, I'd check all my fuses because there is one there for the fuel pump in run. If you jumped out the relay and no fuel, you've got one of three problems:
1. No power to relay and thus to pump (check fuses and check for power at the relay...make sure you have 12 volts...it should ruin for about 15 seconds with the key in the run position.
if you have no power after checking all the fuses, you proably have an open in the line at some point. I would try running a direct 12 volts to the pump to make sure it comes on. If it does, you know the pump is good. If it doesn't pump or ground is bad.
2. Bad pump
3.bad ground.
You have narrowed the problem down to these three. Good Luck.

 

i have done all of that and put a 12 volt lead to the red wire to the relay to keep the fuel pump running. So what fuse or anything else am I missing. Does anyone have a Factory wiring diagram???

 

here you go
http://img.photobucket.com/albums/v639/mgawat/page2.jpg