jmadigan Posted February 10, 2022 Author Share Posted February 10, 2022 That should make the pump(s) run continuously as it feeds the center contact in the relay, the fact that it isn't running continuously makes me suspect the relay. Here are the diagrams from my AllData Pro: Makes you suspect the starter relay or one of the fuel pump relays? Link to comment Share on other sites More sharing options...
85lebaront2 Posted February 10, 2022 Share Posted February 10, 2022 Makes you suspect the starter relay or one of the fuel pump relays? 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 (http://www.garysgaragemahal.com/uploads/6/5/8/7/65879365/florida-man-42_orig.jpg maybe) and then work on correcting it. Link to comment Share on other sites More sharing options...
mat in tn Posted February 10, 2022 Share Posted February 10, 2022 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. where "was " the blue fuse link before? Link to comment Share on other sites More sharing options...
jmadigan Posted February 10, 2022 Author Share Posted February 10, 2022 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. I’ll do my best Link to comment Share on other sites More sharing options...
jmadigan Posted February 10, 2022 Author Share Posted February 10, 2022 where "was " the blue fuse link before? To the starter side of the starter relay it’s not on the I terminal and running the same. I haven’t checked to see if it starts better cold yet Link to comment Share on other sites More sharing options...
mat in tn Posted February 10, 2022 Share Posted February 10, 2022 To the starter side of the starter relay it’s not on the I terminal and running the same. I haven’t checked to see if it starts better cold yet on the starter terminal of the solenoid? the one the wire from the ignition switch goes to also? that would only be hot while holding the key in the start position. off as soon as you let go of the key. Link to comment Share on other sites More sharing options...
jmadigan Posted February 10, 2022 Author Share Posted February 10, 2022 on the starter terminal of the solenoid? the one the wire from the ignition switch goes to also? that would only be hot while holding the key in the start position. off as soon as you let go of the key. The blue fuseable link wire was connected to the starter solenoid on the big terminal that goes to the starter so yes hot in run Link to comment Share on other sites More sharing options...
mat in tn Posted February 10, 2022 Share Posted February 10, 2022 The blue fuseable link wire was connected to the starter solenoid on the big terminal that goes to the starter so yes hot in run the two large terminals are for the starter "only". one is battery voltage un switched. the other is switched to the starter only and is not energized once you let off the key. the two small terminals are different. the "s" terminal operates the solenoid(relay) from the key/ignition switch. some circuits which require constant 12v will use the battery side of the solenoid/relay as a terminal point and that's where you will see two or more wires with ring terminals mounted there. like the voltage for the heavy side of the fan relay, fuel pump relay, ecu relay, headlamp switch etc. then those relays will be operated by the ignition switch, Link to comment Share on other sites More sharing options...
Gary Lewis Posted February 10, 2022 Share Posted February 10, 2022 The blue fuseable link wire was connected to the starter solenoid on the big terminal that goes to the starter so yes hot in run That is not correct. The big terminal that goes to the starter only has power in Start, not Run. So if that's where you have the blue wire then that is a problem. All fuse links that go to the starter relay go on the battery terminal, not the starter terminal. Link to comment Share on other sites More sharing options...
jmadigan Posted February 10, 2022 Author Share Posted February 10, 2022 Ok, first issue is Ford changed the "hot fuel handling package" which is what you have every year from 1983-1987 so the first thing is to find a good (don't trust Haynes or Chiltons) wiring diagram. Basics of the system are found here: https://www.garysgaragemahal.com/460-fuel-systems.html however the wiring diagrams are not there for all years. The fact that it will prime indicates the pumps and wiring are there, priming is via the small blue fusible link on the starter relay (connected to the "I" terminal). On the back of the engine, there is a small switch teed into the oil pressure sender pipe: Pay no attention to the automatic/standard transmission note, it should be with Hot Fuel and Without Hot Fuel. From it a harness runs along the inside of the driver's side valve cover and over to the wiring on the inner fender. On the firewall is a fuel pump relay that this switch powers causing it to change from the priming wire to a battery power source. If the relay is clicking when the oil pressure comes up, then it is probably bad, if not then the oil pressure switch may be bad. If you unplug and jumper the plug terminals, the pump should come on and run, if you get a relay "click" and no pump, then it probably is the relay. Does this wire that should be connected to the “I” terminal have the diode on it as well? Last night I moved the blue fuseable link with the diode to the “I” terminal and there was no change in starting it was a pain to get going I had to manually fill the bowls with some gas until it picked up fuel. I swapped the relay with a spare I had that may also be questionable. The wiring is hacked in this truck there is a 5 pin relay in the fuel cutoff (relay without the resistance wire) with one of the wires clipped off that’s another potential issue I have seen I’m not sure which wire it is but I will check when I’m home. Overall same issue pain to get running but once it picked up fuel it drove fine. Link to comment Share on other sites More sharing options...
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