I took these from another thread, maybe it will help.
https://www.ford-trucks.com/forums/s...ghlight=deboer


<table border="0" cellpadding="0" cellspacing="4" width="100%"><tbody><tr><td nowrap="nowrap"> D. DeBoer
Senior User
</td> <td width="100%"> </td> <td nowrap="nowrap" valign="top"> Join Date: Dec 2004
Location: NE TN
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</td> </tr> </tbody></table> <!-- / user info --><!-- message, attachments, sig --> <!-- message --> I have an 1985 F250 460 dual tanks carbuerated. If you have 2 batteries as I do, The starter solenoid on the right side has a #20 blue wire going to a fusablelink then changing to pink w/black hash. this is the engine start power to your fuel pump relay and their are 2. One is green and the other is Gray and one gets its power from the other one to run the pumps. I'll get out today and make sure what circuit does what. The fuel pump safety switch is the oil pressure switch mounted just under the oil pressure sending unit. if this goes out do not buy tha aftermarket from Mr.Gasket as the mounting end is to small and you need to buy an adapter. this wire is red w/yellow hash and is the constant power on to the fuel pump circuit. This energizes when the oil pressure reaches 15 PSI. this is why the pink/black energizes on start and when the key springs back the red/yellow energizes to feed the pump system. When you get into an accident (Heaven Forbid) and the engine stops, this circuit stops the pump from pumping fuel all over the place as well as the enertia switch which is the one on the inside firewall in the middle near the passinger side and these wires are yellow and they go from the fuel pump relay to the enertia switch and back and route along the fenders around the top of the radiator support and down the other fender. They wasted alot of wire on that one.
But I'll get out and check on those relay's when it gets warmer. I also have elect schematics that will help if you want these.

<table border="0" cellpadding="0" cellspacing="4" width="100%"><tbody><tr><td nowrap="nowrap"> D. DeBoer ********
Senior User
</td> <td width="100%"> </td> <td nowrap="nowrap" valign="top"> Join Date: Dec 2004
Location: NE TN
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</td> </tr> </tbody></table> <!-- / user info --><!-- message, attachments, sig --> <!-- message --> That was your oil pressure sending unit. You should have another one half the size directly below that one with 2 red wires w/yellow hashes on then and that is the fuel pump safety switch.

 

If you look at the diagram below, you will see the oil pressure switch has two wires going to it that are red with yellow hash marks. If the plug you found has two red/yellow wires going to it, then that's it.

 

Yes, my 2 wires that are not connected are red w/yellow hash. It comes out of the wiring harness. There also is a single red wire(not sure of any other markings) that plugs onto the oil pressure switch (back of engine, behind carb, near the EGR valve). I am wondering if someone put in the wrong oil pressure switch.

I did some investigation last night. At the starter relay: there are 2 big posts, 1 is for the POS BATT wire. There are also a couple other wires attached to this post including the 20GA blue which turns into the pink w/black hashes going to the pump relay. That did not seem to be the post where that wire SHOULD be connected, the other big post had the ALT wire. There are 2 small posts, one is the starter wire, the other one does not have anything connected to it.
On the drivers side fender there is a box that holds 2 relays. One is the fuel pump relay(pink/black hash, red, brown w/white line and black-ground). The other I am assuming is the Fuel pump cutoff relay. This one has 5 wires coming out of it (yellow,red w/yellow hashes, resistance-comes off the pink/black hash wire, and 2 black wires. 1 of the black wires is not hooked to anything, just had black tape on the end).
I hope that this can shed some light on my problem and me figure out how to fix it.

Thanks,
Eric

 

You should have two devices on a pipe "T", a big one with one White wire with a Red Stripe, this is you Oil Pressure Sender.


You should also have a smaller one screwed into the "T" that the two wires go to (the Red wires with the yellow hash).

That is wired wrong, the pink w/black hashes goes to the small screw that has nothing on it (I term.).
Also the other big wire on the other side from the Battery goes to the Starter, not the ALT.

This is the Tank Selector Relay.

Yes this is the fuel pump cutoff relay. One of the Black wires should go to a ground and the other goes to the other relay to ground it.

I wanted to know if you could take photos of all of these Items and there locations? You could then email them to me for re-posting for others that have problems with this type system.

 

Does anyone have a diagram of the starter relay and what post is which?
On my truck the connector for the starter is a male type that slips right onto the small post on then front side of the relay. This post is for the alternator? The bigger post above that is for the starter?

I will try to take digital pictures and post them.

 

This may help

 

Thank you subford.
So the battery and the alternator should be on the same post.
The red w/blue stripe wire on my truck goes to the starter!? That should go to the safety switch and the "S" terminal? is that the neutral safety switch?
The blue 20GA/pink w/black goes on terminal "I" ( or "S").

Boy someone really messed me up, didn't they?

I still don't understand why only my rear tank runs when the NEG BATT cable is hooked up and the front tank DID run at least when I turned the key to RUN. Now I can't shut my rear pump off unless I undo the NEG cable. The rear tank has to be spliced somewhere to a always hot wire.

 

[QUOTE=subford]You should have two devices on a pipe "T", a big one with one White wire with a Red Stripe, this is you Oil Pressure Sender.


You should also have a smaller one screwed into the "T" that the two wires go to (the Red wires with the yellow hash).


Do you have a picture of this "T" with both of these devises attached correctly?

 

May be this will help some.



I will get back to you on why the rear tank runs when the Neg Cable is put on.

 

OK, with the PK/BK H wire on the wrong Term it is hot at all times so the Tank Selector Relay has Power on its common at all times. All safety devices have been bypassed. The Fuel Pump Cutoff Relays ground is cut (black wire with tape) and the Oil Pressure Switch is missing so this relay does nothing.
The NC Pos. of the Tank Selector Relay is to the rear Tank so the Rear pump will run whenever the battery is hooked up so they cut the wires to the rear tank.

It should wired like this run the rear tank when the Battery is hooked up. When the key is turned on and you select the front tank the Fuel Tank Selector Switch will put POS (+) voltage on the coil of the Tank Selector Relay and then the rear pump will quit and the front pump will start running.

This is a very unsafe way for this truck to run and could burn up at any time if it has a fuel leak.

For somebody to do this to a truck they were either crazy or there is something else wrong and they did not have the money to fix it or they did not understand it. I would not be surprised to hear that the Tank Selector Valve/Switch is bad.

No I do not have a photo of the Fuel "T".

 

on those relays on the drivers side fender: If I connect 1 black from each of the shut off and the tank selector relays together (butt connector) and ground the other black from the shut off relay to the frame or body of the truck that part should be good, correct? Then I can get the starter relay wired correctly and then see where we are at.

 

Some how the Tank Selector Relay seems to already be grounded (my theory above).
It seamed like you were saying that the Fuel Pump Cutoff Relay had two black wires coming out the bottom and one of them was cut and taped.
I deducted form that, that the other wire went to ground. You did not say much about the Black wire from the Tank Selector Relay but what you said in another post is that the front pump would run with the key on. This means somehow that the Tank Selector Relay is grounded.
Yes, all of the black wires should be connected and grounded.
Does this truck run?

 

yes the truck runs. Last night I had a little time before dark to work on it, I got the ground wires of the relays hooked up like you said in the previous post. 1 ground from each relay connected together and the other ground on the cut off relay grounded to the firewall. I then went to touch the NEG cable to the battery and the FRONT tank pump ran. The tank selector switch is on the front tank. This morning I am going to try to flip the switch to the Rear tank and then touch the NEG cable to battery and see if the Rear tank pump runs. If it does then I will turn my attention to the starter realy wiring and then try to figure out this oil pressre switch thing.

 

Keep us posted on how you are coming and I am looking forward to the photos.
Good Luck.

 

I appreciate you hanging in there on this one.