I have a 1984 ford f-250 460 4x4.
i was not getting enough gas to the carburator causing the truck to only run for 10-15 seconds, i give it gas when it starts to die but it still dies. i ran an alternate electric fuel pump outside the truck from the tank switch over(i have two tanks), and the truck runs perfect.
I have changed the fuel return valve, fuel relay, oil pressure activated fuel pump shutoff switch, oil pressure gauge sending unit, fuel pump, rebuilt the carburetor, adjusted the floats, checked the Interia switch and all the fuses.


Now my gas gauge is not working. I was told to change the fuel tank switch over valve, so i did that today, and now the truck wont start at all. before it would run for 10 seconds and then die, any ideas on what else it could be?

 

I hate to tell you this but most of us with in-tank electric pumps have had issues at one point or another. The gas gauge is also part of the in-tank electric fuel pump. These pumps are around $160 each. I suggest you hook up an Electric pump just in front of the switch over valve and call it good. Be sure to buy a good push-pull pump. I bought a Carter from NAPA.

 

Could you have a clogged fuel line?

 

I don't see anything in post #1 about a fuel filter being changed

 

If it runs OK as stated with an outside electric pump then my guess is not a filter. I agree that should be checked. I ran into this with my 86 F250 4x4 460.

 

Fuel Filter replacement is wise.

There is also a Sump filter in each tank.

Does it matter which tank you run the truck off of? have you tried running the second tank?

 

i know when i went to buy a truck i couldnt get it to stay running so i put gas in a mountan due bottle and screw the cap so it would drip out just enough to keep it running and hold it over the carb

 

it does the same thing with both tanks and i changed the fuel filter and it still does the same thing. Kermmydog, i am taking your advice on putting a fuel pump in front of the switch over valve, i put it on today and the truck runs great, which is weird since my fuel pumps in my tanks are good. But i figure it must be a wiring issue, can't be a fuel line issue because the extra pump works with the fuel lines. the truck has always been dependable this just happpened all the sudden. thanks for the help everyone.

 

Glad you got it fixed

 

I had a similar problem on my 86 F250/ 460 a couple of years ago. It would do the same thing, get enough gas to start but die a few seconds later. The problem was with the fuel pump cut out circuit- cuts pump power in event of accident/rollover.

I am going by memory right now and would have to check my manual later to be sure -but from what I recall the fuel pump power is driven by a relay that is energized when the engine is running only if an oil pressure switch and inertia switch are satisfied. When the ignition is in the start position, the relay if forced to be energized momentarily and the pumps come on to get the engine started. After the switch returns to the run the relay needs to be energiezed via the oil and inertia switches.

The way to check it was to disconnect the starter relay so the engine does not crank, then listen for the pump noise when the ignition is held in start (you can check both tank pumps). This verifies the pumps are running in the start positon. Next you need to jumper the oil switch wire so the circuit thinks the oil switch is closed and put the ingnition in "run". If you do not hear pump noise then the problem is in the cutout circuit, either the oil switch, inertia switch, relay or wiring. The pump noise is quiet so you may need an assistant, I took the tanks caps off and since my tanks are almost always empty they echo pretty well

For me it was not the switches but a connector in the wire harness near the battery that had a pin corroded off. For my truck the inertia switch is on the pass side of the inside firewall, the wire runs out,around the battery, accross the front and up to the relay by the brake booster.

I think my chiltons manual had a good trouble shooting description.

Good Luck
Phil

 

ive got a 83 f100 with duel tanks and the gauge doesnt work i thought bout bypassing the tank selecting valve anybody have anysuggestions on how to fix it?

 

Are both tanks affected by no Fuel Gauge reading?

The selector valve on the frame has nothing to do with the gauge.

If both tanks are affected remove the fuel selector switch in the dash.

1: With the ignition on ACC, temporarily ground out the Yellow/White stripe wire. The fuel gauge should start to rise to full. Do not ground out the wire for very long it can damage the gauge, only do it for a moment to see if the gauge will move. If it does, go to next step, if not replace the fuel gauge.

The Fuel gauge will work on either ACC or Run mode, and it's safer to have the truck on ACC especially if you are under the vehicle... Have the truck in park, brake on, and blocked.


2: With the Selector switch still removed, use a jumper wire, and jump the Yellow/White stripe wire with the Dark Blue/Yellow strip wire in the connector, for the front tank, or the Yellow/Light Blue Hash wire for the rear tank. Make sure you have some gas in the front and rear tanks. If the gauge starts to rise to the level in the front or rear tank, the selector switch is bad. If no change go on to the next step.

3: It's most likely the sending units in the tank.

Ground the sending unit wires together when the truck's ignition switch is in the accessory position.

Dark Blue/Yellow stripe Front tank, to black wire.

Yellow/Light Blue Hash wire Rear tank to black wire.

(you may have to drop the tank to reach them)

Have a friend watch the fuel gauge, if it moves toward full when you ground out the wire, replace the sending unit.

If it doesnt move, then check the wiring between the sending unit and selector switch on the dash.

Most likely a bad ground problem. Use a Multimeter set to ohms, and check for continuity between the black wire and the chassis. If no continuity then repair broken ground wire or corroded connections...

If continuity, then check both ends of the same color wires between the sending unit connector and the fuel selector switch connector in the dash. Should have continuity. If you dont repair broken wires.

Hope this helps...

 

ok cool thanks but i still have a problem who ever had the truck before me put a toggle switch on the dash that says front on one side of the switch i guess it works the selector but the stock switch still switches or i think it does. when i switch the stock switch i can hear someting clicking and the toggle switch did the same thing for awhile but i dont think it does it now.. i need a lot of help!!!!!!!!!

 

You got to love those previous owners. :P


You are going to have to find out what that extra toggle switch does and get back to me on it. What are the color wires going to the extra switch, and where those wires hook up to the factory harness.


If I were to guess, and it's all I can do is guess... who knows what is in some previous owners minds. The toggle is to replace a defective portion of the factory selector switch. But I have no idea which portion. One side of the factory switch controls the gauges, the other side controls the fuel selector valve. etc...

It looks like you are going to need a new selector switch for the dash at anyrate. And we will try and eliminate the extra switch altogether.

 

my truck is at my grandmothers right now but when i get over there i will check it out thanks