Archived Unable to prime fuel filter

[Denis]

I have a '97 with stock engine and fuel system. It ran fine until this afternoon and had good fuel oil pressure. Decided to do some routine maintenance; change F. O. filter and fuel heater inlet screen. Now I can't prime my filter. Have read some of the past threads and checked many things but can't find and air leaks. With the fuel filter removed and a separate line filled with fuel going to the Fuel heater the priming plunger doesn't pump. Is it possible for the pump to work fine but the priming plunger does not work at all???

 

[fox]

Crank the engine 1 turn, the lift pump is up on the lobe.

 

[Denis]

I tried that still no pumping action.

 

[Missouri Mule]

Crack open the banjo bolt/nut that supplies the fuel filter(should be on top toward firewall). See if when you pump the primer air/fuel starts to come out between bolt/nut and washer.



There is a check valve for the primer button/plunger that could of went bad.

 

[Joe G.]

Remove the short curved hose and connect your test hose directly to the lift pump. If that works remove your fuel heater from the fuel heater/pre-filter assembly and throw it away. Email me at -- email address removed -- for a copy of my 12 valve fuel supply system write up, how it works and how to fix it.

 

[Denis]

Replaced pump

Could find no other problems or leaks so I replaced the F. O. pump with a spare. Now able to prime filter fine.

Very strange; old pump works fine by engine plunger but not using hand plunger.