Well guys. Heres the first problem out of my new truck.
Its a 1984 F250 with a 460 and a 4 speed.
Last night i was driving home from a bond fire at a friends house. The truck was acting fine all day. Put about 75 miles on it earlier with no problems. Well i started the truck up and let it warm up for about 10 minutes (til the choke turned off. Then got in the truck and left. I got about a mile away from her house and the truck started puttering and eventually kieled over. I was in a hill by my school so i was able to coast into the parking lot into a spot.
I tried starting the truck an only got a small sputter then nothing. I got out and noticed i couldnt hear the fuel pump in the front tank. I turned the key on and off a few times and still got nothing. Well it was about 1:30am and i wasnt really in the mood to do anything on the truck so i called my friend and was able to get a ride home in her 2004 3500 cummins.

So after a short nights sleep i headed back out there this morning to see what i could do.
So i started off by pulling the fuel line off the carb and seeing if any came out when cranking the engine. I only got a few drops. Then ichecked all the fuses. None were blown. I heard a while back about the pump shutoff switch under the passenger dash. Well i found it and the white button was popped up. Is it supposed to be up or down inside the unit?

Well i had plans this afternoon so i decides to just tow it home so it i out of the way for school tomorrow.

Sorry for my lack of info. Im very new to electric pumps so I am going off the little bit that i read this morning.

Do you guys have any tips on what i should do now?
Thanks guys!

 

Push the button down .If that don't work check fuel pump relay I believe its green on left side inner fender .A buddy of mine had his relay burn up on his truck we converted it to a mechanical fuel pump

 

You should have a extra wire over at your starter relay that most trucks don't have. You will have the two large wires, the smaller red/blue wire, and another one that may be blue or pink/black. If you find this extra wire, take a jumper and jump this small wire to the battery + terminal. The pump should run. If it doesn't check that safety switch again. It will have two yellow wires on it. If you have a testlight, poke the wires going in and out, with the jumper going to the battery + still in place from the first test, you should have voltage coming in and going out of the safety switch.

 

Do you have any pictures? The PO added 2 extra solenoids to it and mixed a few wites around so I am not to sure if the wires are still correct.... He had a stator or a in-bed camper hook up and another one that goes down into the frame somewhere?

As with the relay, i read that if it clicks when you turn the key on it is still good. Is that correct? Because i can hear it clicking when turning on an off.

So what sires should i try to jump off the positive terminal? And what should they do?

 

Did you ever figure out your problem? I am having a very similar problem with a 83 F250(460, 4b, auto.) w/ dual tanks but the rear tank has been disconnected.

 

I have a dual battery isolator relay (solenoid). It looks a lot like a starter relay and it clicks when I turn the key on. When it clicks it's energized and it ties the house battery into the chassis battery and charging circuit.

---> if yours is the same as mine, your fuel pump does not run with the key in run and the motor not running...

The fuel pump receives its power from the starter relay two ways:

1) the bypass circuit energizes the fuel pump only when the starter is engaged. The bypass wire is a 20 gauge fusible link (sometimes hard to come by) that attaches to one of the small posts of your starter relay. The fusible link can burn out and cause this circuit to fail.

As Franklin suggested, you can jump a hot wire from the battery to the bypass terminal and you should then hear the fuel pump run.

Note the other small terminal on the starter relay is the starter signal from your key switch. So it you jump to the wrong small terminal the starter will engage.

2) the normal operating circuit. This is also a fusible link (and possible point of failure). It's a ring terminal attached to the large hot terminal of your starter relay. From there the wire goes to the inertia switch (which should be pushed all the way in BTW) and then on to the fuel pump relay.

You should have power from the starter relay, through the inertia switch, to the fuel pump relay at all times.

But, in order for the power to pass through the fuel pump relay to the fuel pump, the fuel pump relay has to receive the signal from the oil pressure switch.

The oil pressure switch gets its power from the fuse box (blown fuse, possible point of failure) through the key switch (hot in run and start). The oil pressure switch is located on the top of the motor all the back toward the firewall. If you've got an oil pressure gauge there will be a round can with a wire attached to it (the oil gauge sending unit) and at the base of that you will find the oil pressure switch with a couple wires attached.

If you disconnect the wires, with the key ON one of them should be hot. And if you jump the terminals with the key on the fuel pump should run.

In a nut shell:

The fuel pump runs while cranking the starter or when it's running and has oil pressure...assuming everything is working as designed. The fuel pump does not run with the key on but motor not running (unless somebody has jumped the oil pressure switch).

Yikes! I hope that helps.

Oh, and don't forget to check your fuel filter(s).

 

Yes, there are additional relays and switches for dual tanks but I don't have any experience with those components.

 

When the pump was still working it ran constantly with the key on. Whenever the key was in the ru position, even without the engine running, it would cycle.

 

If that's the case then I'd guess a prior owner has already jumped the oil pressure switch and the first thing I'd do is inspect the jumper wire to make sure it didn't work loose or short to ground.

Next thing I would do is inspect the fusible links at the starter solenoid that supply power to the fuel pump to see if they are still good.

Next thing I would do is jump a hot wire to the fuel pump bypass wire to see if the fuel pump will run that way.

If the fuel pump runs by hot wiring the bypass then I would:

Check for power at the fuel pump relay, hot all the time, coming from the starter solenoid.

Check for power at the oil pressure switch with the key on. If there is no power at the oil pressure switch with the key on the fuse is suspect.

If you have power at the oil pressure switch and have jumped the terminals then you should have power from this circuit at the fuel pump relay with the key on.

If the fuel pump ran when you applied power to the bypass wire, and If you have power at the fuel pump relay from the starter relay hot at all times, and you are getting power to the fuel pump relay via the oil pressure switch circuit by jumping the switch and with the key in run, then the fuel pump relay or fuel pump relay ground is suspect.

Beyond that there might be problems with the dual tanks switches and relays but I don't have any direct experience with those components and have little to offer.

 

Yes, that's not right, someone has already monkeyed with the wiring. So get ready for that. Who knows what they did or how they did it.

 

First of. Where is the oil preassure switch and how can i tell which wire is the "jumper wire"?

Second. When you say startor relay are you meaning solonoid? The little plastic cylindrical box with the 4 prongs on it next to the battery? I believe thats what youre talking about, just want to make sure. I havent done much looking but from what i can see there are no fuseable wires attached/running from that. Maybe im not looking in the right place.

Third. The fuel pump bypass wire.... Would that be the wire that was put in to bypass the oil preassure switc or no? I have no diagrams or a manual and im use to good ole mec. Pumps.

An hopefully last. Where is the fuel pump relay an ground? If its in the undercarriage then ill need some good direction to find it. The truck may or may not be caked in mud as we speak. Haha.

The rear tank didnt work when i bought the truck so i have never fussed with it. Only turn the pump to the rear tank when the truck will be sitting for a few days to drain all the gas in the carb. Other than that i have always had the seitch to the front tank an this is the only problem ive had.

The PO of this truck could learn something from a monkey when it comes to wireing. The truck has 3 solenoids (only 1 is original), "custom camper plug in" in the bed that is wired beyond terrible, and about 150 feet of stray wire in the engine bay. He had wires running from behind the grille back into the firewall then stops there. He had hot wires running from the battery down the frame to a cap. And alot more. Wireing was not his forte i guess.

Tomorrow ad thursday i do not have work and if the weather is clear i'll have all day to work on the truck.

Thanks for the help guys. Hope to hear from ya soon.

 

The oil pressure switch is on the top of the motor all the way back at the firewall. It you have an oil pressure gauge look for the oil pressure sender, it's a round can looking thing with a single wire attached to it. The pressure switch is at the base of the oil pressure sender and normally it would have a two wire connector plugged into it. However, from what you describe, I suspect the wires have been disconnected and a jumper wire has been added jumping the terminals of the disconnected wires.

It is probably more correct to say starter solenoid. Follow the positive battery cable from the battery and it should be attached to one of the big lug terminals of your starter solenoid. Also attached to the same big lug as the positive battery cable should be a ring terminal with a length of fusible link, then a splice to regular wire. This is the main power supply for your fuel pump. (In addition there should also be another bundle of larger wires attached to the hot lug of the starter solenoid but you shouldn't have to mess with those).

When I say bypass wire I am NOT referring to the jumper wire you might have jumping the oil pressure switch.

Proceed at your own risk.

The bypass wire I am referring to is a short length of fusible link spliced to regular wire that is attached to one of the small lug terminals of your starter solenoid. This wire bypasses the fuel pump relay system entirely and is wired pretty much directly to your fuel pump. If you apply current to this wire the fuel pump should run and confirm the pump works if it gets power.

A couple words of caution: make sure your truck is NOT IN GEAR if you decide to hot wire the fuel pump bypass. There are two small lugs on the starter solenoid...one is the fuel pump bypass and the other is the start signal wire. If you apply power to the wrong small lug the starter will kick and if the truck is in gear it will jump! DANGER, look out!

The other word of caution is not to try and run the truck using the bypass. That's not a solution. The bypass is only designed to run while the starter is cranking. If you run it that way long term you could burn something up. Especially if somebody has eliminated the protection of the 20 gauge fusible link and is just running the bypass wire directly to the small lug of the starter solenoid.

On mine the fuel pump relay is a smallish square green box with wires plugged into it and I only have one, but yours might have several square green boxes (relays). One for the fuel pump relay and the others as part of your dual thank switch wiring. I've heard of people confusing the relays and changing out the wrong one, or getting the wrong one at the parts store...

Don't forget to check your fuel filters too. Clogged filter = no gas.

Good luck.

 

Heading out to work on the truck now. Also 1 more question. The pump shut off switch under the passengerdash. Should the white button be popped up or pushed down?

 

Push it down.

 

It doesnt stay down..... Should it?