jmadigan Posted February 9, 2022 Share Posted February 9, 2022 Hello all I have a 1983 f250 460 4x4 4 speed with the in tank low pressure pumps. First winter owning it and im chasing a fuel problem. Carb stays full of fuel starts up fine then drains bowls I crank to refuel carb then it drains again i repeat this 3 or 4 times and then it will run just fine. It only happens in the cold. This is telling me the pumps dont prime the lines. Any ideas what could be causing this? Im thinking of running a momentary switch to prime the lines to prevent this from happening any ideas on where to hook a push button switch to turn on the pumps to prime? but shouldnt the pumps be priming in the run position? Link to comment Share on other sites More sharing options...
Gary Lewis Posted February 9, 2022 Share Posted February 9, 2022 I'm confused. The carb stays full of fuel over night, but when you start it the carb loses fuel? Where does the fuel go - into the engine or on top of the engine? Link to comment Share on other sites More sharing options...
85lebaront2 Posted February 9, 2022 Share Posted February 9, 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. Link to comment Share on other sites More sharing options...
grumpin Posted February 9, 2022 Share Posted February 9, 2022 The fuel pump should come once you start cranking the engine and stay on with oil pressure IIRC. I wouldn’t think your carb is draining, I think it’s cold and didn’t stay running. How is your choke adjustment? Link to comment Share on other sites More sharing options...
jmadigan Posted February 9, 2022 Author Share Posted February 9, 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. I will give this all a look and report back Link to comment Share on other sites More sharing options...
jmadigan Posted February 9, 2022 Author Share Posted February 9, 2022 The fuel pump should come once you start cranking the engine and stay on with oil pressure IIRC. I wouldn’t think your carb is draining, I think it’s cold and didn’t stay running. How is your choke adjustment? Let me also say I put a quick fuel brawler with a manual choke on the truck it has sight glasses for the float levels so before I start in the morning I can see the float levels are fine it starts up fine but I can watch the fuel bowls empty while it runs crank the engine over refill the bowls and repeat 3 or 4 times (about the time the battery is throwing a white flag) then the bowls will refill on their own after a while. It happens every morning or after work if it’s below freezing. Above freezing this doesn’t happen. 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. Blue fuseable link wire is on the starter wire on the terminal not in the “I” is this my problem? Link to comment Share on other sites More sharing options...
Gary Lewis Posted February 10, 2022 Share Posted February 10, 2022 Let me also say I put a quick fuel brawler with a manual choke on the truck it has sight glasses for the float levels so before I start in the morning I can see the float levels are fine it starts up fine but I can watch the fuel bowls empty while it runs crank the engine over refill the bowls and repeat 3 or 4 times (about the time the battery is throwing a white flag) then the bowls will refill on their own after a while. It happens every morning or after work if it’s below freezing. Above freezing this doesn’t happen. Given that description, which helps my understanding a bunch, I'd guess that your oil pressure switch isn't closing and that causes the fuel pump not to run when in Run. I would put a jumper across the switch to bypass it and see if that causes the truck to run. Link to comment Share on other sites More sharing options...
jmadigan Posted February 10, 2022 Author Share Posted February 10, 2022 Given that description, which helps my understanding a bunch, I'd guess that your oil pressure switch isn't closing and that causes the fuel pump not to run when in Run. I would put a jumper across the switch to bypass it and see if that causes the truck to run. I think the oil switch is working because after the bowls finally fill on the 4th or 5th try it runs normal. Should I jumper the wires anyway and try it in the morning. I also put the fuseable link in the I position on the relay. Link to comment Share on other sites More sharing options...
85lebaront2 Posted February 10, 2022 Share Posted February 10, 2022 Blue fuseable link wire is on the starter wire on the terminal not in the “I” is this my problem? 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: Link to comment Share on other sites More sharing options...
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