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Tim Basham
Tim Basham, ASE Certified Master Technician
Category: Ford
Satisfied Customers: 743
Experience:  30 year multi line tech ASE cert master tech ASE engine machinist, Ford Bronco builder
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1985 ford F350: carburator..It has 2 tanks with electric fuel pump

Customer Question

I have a 1985 ford F350 with 460 motor. It has a carburator. It has 2 tanks with electric fuel pump in each tank. It would pump gas as long as you cranked the motor then when the truck started and you let off key it would stop pumping. What is the problem
Submitted: 8 years ago.
Category: Ford
Expert:  Tim Basham replied 8 years ago.
There is a oil pressure switch, fuse and cut out relay used to power up pumps after engine has started I ussually find the oil pressure switch to be the problem. fuel system wiring
Customer: replied 8 years ago.
Reply to Tim Basham's Post: I have not had time to check the truck out. I will try to check it on 9-29-06 and let you know if that is the problem. Thanks
Expert:  Tim Basham replied 8 years ago.

That is fine Let me know how it goes and if you need any more info.

 

Customer: replied 8 years ago.
Reply to Tim Basham's Post: We changed the switches and it did not help. We have the pump wired to it will come on when you turn key on. But I would like to have it fixed right
Expert:  Tim Basham replied 8 years ago.
Ok I am trying to research it more for you I want to verify its a f350 truck and not a e350 van.
Customer: replied 8 years ago.
Reply to Tim Basham's Post: F350 Ford
Customer: replied 8 years ago.
Reply to Tim Basham's Post: I am waiting for the answer on the 1985 F350 Ford truck. Thanks
Expert:  Tim Basham replied 8 years ago.

Ok I am looking for a better circuit description for this system but am finding very little. I have attached the diagnostic info for both dual tanks 7.5l systems. I beleive your is a hot fuel handling.

Do you have a test light or multi meter to test for voltage? If you do lets see what voltage you have at the oil pressure switch on the red/yellow wire. Also what voltage you have at the yellow wire on the inertia switch both into and out of the switch.

diaga

diagb

Customer: replied 8 years ago.
Reply to Tim Basham's Post: Will it hurt anything to run the truck with the pump wired to come on when I turn the key on. We Have it wired so that front tank works and runs good. But we had to rewire it. Thanks
Expert:  Tim Basham replied 8 years ago.
It will not hurt anything but in case of a accident or other problem with fuel lines the fuel pump will continue to run even if the engine doesn't. This is the purpose of the oil pressure switch. The inertia switch shuts off the voltage in case of accident it opens circuit apon any severe impact. if you just straight wire from Ign switch just remember to make sure key gets shut off in case of any accidents.
Tim Basham, ASE Certified Master Technician
Category: Ford
Satisfied Customers: 743
Experience: 30 year multi line tech ASE cert master tech ASE engine machinist, Ford Bronco builder
Tim Basham and 9 other Ford Specialists are ready to help you
Customer: replied 7 years ago.
Relist: I still need help.
I have a 1985 ford F350 with 460 with a carb. it has 2 fuel tanks with fuel pump in each tank I had problem with the pump. I hooked the pump where it works when you turn the key. The truck runs real good setting still. but when you drib it. it misses when you pull it down. it has a new tuneup. if you change gears it clears up. it does not doit all of the time. what is the probvlem
Expert:  Tim Basham replied 7 years ago.

Do a fuel supply test when problem occures. These engine need a very good fuel supply or the condition you discribed will occure. I have attached the test description of the flow test.

graphic

Customer: replied 7 years ago.
Reply to Tim Basham's Post: I put a inline filter on the truck just before the gas gets to carb. I did this just to make sure it gets nod dirt in carb. it also has a filter in card. I would really like to hook fuel pump up like they are supposed to but I do not know how. I know they are supposed to work off of the oil switch
Expert:  Tim Basham replied 7 years ago.

The filters shouldn't be causing this problem unless they are clogged. I would love to help you get the wiring on this one straightened out but with ford having several different set ups on these and not being able to check the truck in person I don't knwo how else to tell you to check for the problem that is related to the fuel pump wiring problem.

As for the running problem it does sound like your having a intermittant low fuel problem. This could be caused by a bad pump or a restriction in the system somewhere.

Customer: replied 7 years ago.
Reply to Tim Basham's Post: the fuel pump was weak so we put new fuel pump and all lines and filters are open. the truck runs better but still misses a little when pulling down. we had to wire pump so it runs as soon as key is turned on but I dont think that should matter. we are just using one tank. can you help.
Expert:  Tim Basham replied 7 years ago.
If you have good fuel flow and pressure now and its still not running like you think it should then either you have a carb problem or a ignition problem. what shape are the plugs, wires, cap and rotor in.
Customer: replied 7 years ago.
Reply to Tim Basham's Post: new plugs wires cap and rotary. I am going to drive it more today. Thanks
Expert:  Tim Basham replied 7 years ago.
Just let me know how it does. With all the fuel problems you may have lean fouled the plugs and just needed a good tune up.
Customer: replied 7 years ago.
Reply to Tim Basham's Post: The answer you gave did not really help the truck. Thanks
Customer: replied 7 years ago.
your answer did not help the truck it still does it something mostly when cold
Expert:  Tim Basham replied 7 years ago.
Its sounds like your running lean in the carb then or the choke is not working correctly. It shoould have a holley carb on it and may need rebuilt. Honestly these carbs are not bad to do but several thing are critical to get them right. I really don't feel there are good carbs for do it your selfer to learn on. If you are familar with the holley then it shouldn't be a problem. Before I tore it apart I would inspect closely for any slight vac leaks that could also cause the lean condition. You can do this with a spray bottle of water. Spray around the base of carb and intake to head areas and see if idle changes. If it does then you have a gasket leak.
Customer: replied 7 years ago.
Relist: I still need help.
I put new fuel pump replaced carb. and gasket. The truck still misses at low speed when you are pulling it down. it does not do it all of the time. This may sound crazy but when the truck is running real good, the heat guage is about a quarter of way and when it is missing the heat guage is barely off the cold mark but the motor is the same temp. and also the other guages move a little further when it is running good. could there be a short in the wiring causing the truck to miss. You never know when the truck is going to miss but if it does you can see the guages are like that everytime
Customer: replied 7 years ago.
Relist: No answer yet.
Customer: replied 7 years ago.
Relist: I prefer a second opinion.
Customer: replied 7 years ago.
Relist: I still need help.
the 1985 ford is still causing problem. I have put new igniton switch, fuel pump, wires, plugs, dist. cap, rotary button and carb. sometimes the truck rums perfect and when starts missing mostly pulling down. you can turn the key switch like you are going to start and it will run perfect.every time it misses you turn the key switch it clears up. then when you let go of switch it misses again. then we installed new switch but it still does the same thing. thanks
Customer: replied 7 years ago.
Relist: No answer yet.
I have no answer on my queston
Customer: replied 7 years ago.
Can you see the message that I wrote on Jan 27 2007. I cannot ujnderstand why knowone will answer. I have money in the account. Thanks

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