Fuel Issues.

could this be something as simple as not enough oil pressure due to oil being too thick from the cold. you said it goes away after warming up. another possibility is a clogged fuel filter. made worse by the cold

I thought about that I was using rotella t4 to keep the cam alive but I switch to 5w30 to see if that was it. The oil pressure gauge comes right up I’m not sure how much oil pressure is there though. Also I have the Wix 30033 filter so I can see in there and there is no movement of fuel until it finally picks up.

an in-tank pump is always primed. as long as there is gas in the tank. it does not need to pick up. either it's not running or its not flowing. does the system have a return line? If so, that should eliminate head pressure from stopping flow.

The diode is in the pink with black hash wire originally, it is beyond the fusible link and may be in a "bulge" in the actual wire. If it is open then the priming function won't work, the pump will not run until the oil pressure switch closes.

Please, those of you who are not familiar with a 460 "hot fuel handling package" refrain from interjecting comments. The system is confusing enough, compounded by (a) Ford changing it almost yearly during it's run and (b) trying to figure out what has been done in 39 years of different owners and shops working on it.

Here is the wiring I removed from Darth when I converted to EFI. This is from the starter relay around, down the left valve cover and over to the fuel pump cutoff relay. Mine did not use the tank selector relay as it is a 1986 system.

Pumps are, but the carburetor may not be, fuel evaporates from heat when sitting, and Holley carbs were known to leak at the cork gaskets.

The wire i moved to the I position is the wire you labled "blue fusable link" it connects to the pink black hash wire. Also for those of you asking the carburetor is not losing fuel I have sight glasses the carb is full but when running it drains until i fill it by cranking and eventually it will fill on its own. So I'm loosing prime in the line. There is a return line hooked to the hot start canister. The fuel system is working as it should except for priming the carb when starting. It sounds to me like i need to test the Blue fusable link and the relay system am i correct?

Yes sir, that is correct. Are you comfortable following a wiring diagram? I posted them earlier, it is in two parts, one follows the gauge system wiring, the other the fuel pump power. If you unplug the yellow wires at C144 with the blue fusible link still on the hot side of the starter relay, there should be battery voltage there. If not then there is a problem with the fusible link. Look for a melted area and gently tug on the ends. If there is a melted area, that's the problem.

If you have battery voltage there, try jumping the pins in the male side of C144 and see if you hear a pump run and a hiss from the vapor separator. If that works, then go under the passenger side of the dash, on the heater duct, you should see two yellow wires plugged into a switch with a push button on top, push down on the button and see if it clicks and stays down.

If jumping the pins in C144 doesn't work, then move over to the relay under the shield on the driver's side firewall. Check first for battery voltage at the pink with black hash wire, this is the feed from the blue fusible link. If you have battery voltage there with the relay plugged in, then you will need to check for battery voltage at the yellow wire first, then the red and the brown with white wires, one should have power, if not the relay is bad. If you do not have power at the pink with black hash wire, then the diode may be open or the wire may be broken.

If you find the tank selector relay is bad, a standard Bosch cube relay will functionally replace it with a socket. If it is exposed under hood, seal the back side of the socket with RTV.

I can follow the diagram. I will check this all tonight when i get home and report back. You wouldnt happen to have the part numbers for the bosche relay would you? Also there is one thing i should mention erlier this summer the green connector on my fuel pump relay has a break in the yellow wire inside the pigtail. I went to the junkyard and got a new one and spliced it in place because i could not for the life of me de-pin the pigtail. So needless to say I shortened the resistance wire by about an inch which i know your not supposed to splice that wire could this be another issue?

Yellow doesn't matter, it is not resistance. I wish I had known, I just disassembled a green and a brown Ford relay plug from an EFI truck, but they are the same.

To remove the wires, first carefully remove the red locking cover, then at each wire, where the tabs on the cover inserted, there is a plastic latch, carefully push it away to the edge of the slot, the wire should pull out from the bottom.

The Bosch relay is what is called a mini cube relay, they are used by just about everybody, they have 5 pins roughly 1/4" wide laid out with the two coil pins on the sides, the center contact on one end and the NC and NO contacts opposite. The Bosch numbers for the terminals are: 30 common; 85, 86 coil; 87 NO, 87a NC. Here is a not super picture, this is a Chrysler one with a skirt for underhood use and it takes a latching socket:

Okay ill look for a bosche relay. But what i mean by cutting the resistance wire is i spliced in an entire socket so every wire was shortened about an inch including the pink and black resistance wire

85lebaront2 wrote

The fuel pump cutoff relay. What bothers me is the way things are hooked up now the pump should be running even with the key off. The fact that it isn't makes my suspect that there is an open circuit somewhere between the blue fusible link and the tank selector relay.

Fuse link T is the blue fusible link, the way it is connected, the pink with a black hash wire should have battery voltage through the diode to the relay socket, you should also have power at the fuel pump cutoff relay
640, Red with Yellow Hash is powered by the oil pressure switch when closed; 57, black is ground; 37, Yellow is powered directly from the battery through the inertia switch (inside on the heater duct, passenger side); 787, Pink with Black Hash, is powered when the relay coil is powered by the oil pressure switch. If the power is on circuit 787, then the pump will run.

You need to check these items and figure out how hosed up the wiring is ( maybe) and then work on correcting it.

All of this checks out pink with black has power when running

85lebaront2 wrote

Yes sir, that is correct. Are you comfortable following a wiring diagram? I posted them earlier, it is in two parts, one follows the gauge system wiring, the other the fuel pump power. If you unplug the yellow wires at C144 with the blue fusible link still on the hot side of the starter relay, there should be battery voltage there. If not then there is a problem with the fusible link. Look for a melted area and gently tug on the ends. If there is a melted area, that's the problem.

If you have battery voltage there, try jumping the pins in the male side of C144 and see if you hear a pump run and a hiss from the vapor separator. If that works, then go under the passenger side of the dash, on the heater duct, you should see two yellow wires plugged into a switch with a push button on top, push down on the button and see if it clicks and stays down.

If jumping the pins in C144 doesn't work, then move over to the relay under the shield on the driver's side firewall. Check first for battery voltage at the pink with black hash wire, this is the feed from the blue fusible link. If you have battery voltage there with the relay plugged in, then you will need to check for battery voltage at the yellow wire first, then the red and the brown with white wires, one should have power, if not the relay is bad. If you do not have power at the pink with black hash wire, then the diode may be open or the wire may be broken.

If you find the tank selector relay is bad, a standard Bosch cube relay will functionally replace it with a socket. If it is exposed under hood, seal the back side of the socket with RTV.

All of this is fine 13 volts while running maybe I’m chasing ghost problems. I’ve heard there may be check balls in the pumps to keep the pressure from bleeding off is this correct?

I’m really contemplating just adding a 2 way momentary switch to prime from each tank before I crank on it. Can I tap into the brown/white and red wires at the relay to accomplish this?

Running obviously wasn't the problem, it was the starting priming circuit. If everything was working correctly, the way you had it wired, blue fusible link to battery, the pump would be running even with the key off.

You were asking earlier about getting the wires out of the relay sockets, so here it is in pictures, I am using the brown socket which I believe would be your fuel pump cutoff relay (wire colors are wrong as this is from a 1990 F250, EFI 460)
First, the relay socket top and bottom:



Note the thin slot left side top, this is where I insert a metal nail file to push up on the retainer tabs:



Once the retainer is lifted enough to put a small pick or screwdriver under it simple work it out.



If you look carefully at the retainer, some of the tabs have small hooks, these are what keep it in the socket. With the retainer out, each terminal has a plastic latch that holds it in place, push the latch away from the metal terminal until the terminal can be moved away from the retainer area.

The blue wire is not on battery power I have it wired to the “I” post on starter relay it was originally on the big lug that goes to the starter. If I measure voltage on the “I” lug I have nothing. When I crank the truck I get 12+v on this lug. I measured voltage on the pink and black wire I get 13 when running yellow I get 13 while running red and black 13 while running red 13 brown and white 13 if I unplug the inertia switch it cuts dies as it should all my wiring seems to be functional are these measurements correct?

Actually hold on I did try blue wire hooked directly to battery side of relay and never got a pump. I also ohmed out the blue fuseable link and got 0 ohms so now I am thinking that wire is shot.

It just hit me that I would still see voltage because the resistance wire is tied into this wire. That’s why there is a diode… so this means I need to find a new fusable link. Can I just splice a new fusable link in before the diode or do I need to source a whole new wire?

Yes, the diagram gives the size, just be sure to connect it to the "I" terminal.

Thank you I’ll give this a shot and report back it will be a few days and thank you for showing me how to get those connectors apart it was a mystery to me

No problem, I completely redid the wiring on my truck, everything is pretty much 1996 now I learned how to get them apart, the ones that do come apart.

Before you go looking for a fusible link, see if you can find the diode in the harness, Ford eliminated them in the newer trucks so it may have been a high failure item. If you can locate it, jumper it across and see if the priming function works then. If it does, you're good to go with it.