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George H.
George H., ASE Certified Technician
Category: Ford
Satisfied Customers: 18667
Experience:  ASE Master Tech 15+ Years
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I have a 1972 f-100 with 390. The fuel pump is mechanical

Customer Question

I have a 1972 f-100 with 390. The fuel pump is mechanical and is the type that has the fuel filter canister is attached to the fuel pump itself. I neglected to change this filter for many years and the truck died recently on the road. I could keep the truck running when putting fuel down the carburetor so figured it was the pump. I took the cannister off when I got the truck home and it has at least 1 inch of junk in the bottom of it and the filter was completely clogged. I changed the filter and cleaned out the cannister. The truck ran great for another 2 weeks and then quit again. There is a fuel filter back by the tank so which was also completely clogged. So I changed that and the truck ran well again for about a week then quit again. No output from fuel pump at all. Today I replaced fuel pump. Now I have gas at output and truck ran for about 15 minutes then quit again. Still having fuel at output side of pump now, but I can only keep truck running by putting fuel in carburetor. Any ideas?
Submitted: 9 months ago.
Category: Ford
Expert:  George H. replied 9 months ago.

Hello I will help,

All that stuff has to be coming from somewhere and that is the tank. You need to drop the tank and get it cleaned, replace both filters and check the carb bowl to see what is in there.

You also need to be sure any rubber parts of the fuel lines are not cracking, it only takes a pinhole in a line to prevent the pump from pulling fuel from the tank.

Please let me know what I can do to help

Thank you

Customer: replied 9 months ago.
It seems there is pressure now coming form the fuel pump filter canister as the fuel is squirting out from around the rim. I can fix that by replacing the seal ... but should there be pressure in the filter canister attached to fuel pump? Also where is bowl in carburetor? I have a holley 650 4 barrel.
Expert:  George H. replied 9 months ago.

To access the float bowl in the carb you will need to remove the top and any linkage for the choke or accelerator pump that prevents you from removing the top/

If you have pressure in the filter try opening the fuel line to the carb and see if the pressure comes out there. The spec is a pint of fuel in 15 seconds of cranking the engine. If the pump delivers that and the filters are clean the needle and seat in the carb might be stuck closed. Getting all the gunk out of the carb is what would need to be done. Installing a :cab kit" will replace many parts and gaskets, you will have to manual clean the jets and air bleeds. If this is your first time cleaning a carb I suggest spending a few hours watching you tube videos on how to do it. You may not find your specific carb but the process will be explained. The carb kit will have a blow up of the carb parts.

Expert:  George H. replied 9 months ago.

If you have further questions please let me know, if nothing further please complete the rating

Thank you