IP fuel flow

[mangus580]

Ok, I have acquired a 95 parts truck for the engine. In trying to start it today, I have discovered it will not flow fuel through the IP. I am presuming that with the lift pump running, and the key on, I should get a nice steady stream of fuel out the return port.

I have removed both the return and intake fittings on the pump. Attempted to blow air through (which nets a MINOR flow out the return). I have had the shutoff solenoid off to verify that is working properly.

Nothing!

So... any ideas? The truck has sat for about 5 years. The fuel doesnt smell the 'best'. Am I up against just swapping the pump with another one? (have a couple spares)

Sux that I have to swap the pump to even make sure it runs before I yank it to put it in the new Burb...

 

[schiker]

Are injectors getting fuel? Have you loosened the injector lines at the injector to see if they will weep fuel after cranking?

I don't like the sound of blowing air through it. Air is gonna cause problems. I'd treat it like a severly air locked IP now. I don't know but maybe try another FSD/PMD. If the fuel metering solenoid is not closing not sure if the internal circuit is flowing to "pump" fuel internal.

 

[mangus580]

Are injectors getting fuel? Have you loosened the injector lines at the injector to see if they will weep fuel after cranking?

I don't like the sound of blowing air through it. Air is gonna cause problems. I'd treat it like a severly air locked IP now. I don't know but maybe try another FSD/PMD. If the fuel metering solenoid is not closing not sure if the internal circuit is flowing to "pump" fuel internal.

schiker, I agree with what you said. My issue was before I even started messing with it, I was getting no fuel flow out of the return line on the IP. Isnt the IP supposed to let fuel flow through it and back to the tank pretty constant?

 

[schiker]

Yes, the IP recirculates a portion of the fuel while running. Not sure how much or exactly how. There are tons of little check valves, balanced valves and timing ports such that as the IP rotates it always circulates fuel internal. Fuel is what cools and lubricates the IP.

Its not a fill and wash through I don't believe; I think its more a pump through. I read a blurb once that the actual return fuel valve internal is suppose to be have something approx like 15 psi opening pressure (its a little spring relief check valve thingy somewhere).

I have heard of a transfer pump internal to the pump but never seen it. I think its more the plungers themselves draw and push fuel during rotation. Then the fuel metering solenoid, porting, and checkvalves direct the circulation.

Might try to add some fuel cleaner to the inlet or fill the fuel manager with diesel fuel conditioner and cleaner (nothing real harsh) and take off the injector lines and spin it.