Hello,
I've read miles of threads pertaining to this very issue but still need some help from those of you who know much more than me on this subject.

I'm working on a 1997 (1996.5) Ford F250, 5.8l 351w, 4x4, Ext Cab.
I stalled it one day, and my front pump has not worked since. I just replaced the pump tonight (Just the lower part, not the whole assembly), now the fun begins.
When I turn the key on, engine off, I hear the 3 second prime, but it's quiet, not enough fuel pressure to fully start the truck.
I do the same to the rear, but it's louder (normal loud), full pressure (not psi tested yet, tomorrow hopefully), truck fires right up. (Been running on just the rear for awhile, but have a big trip planned...)

My issue is the front fuel pump. I'm thinking bad wiring or break somewhere not allowing proper voltage to the pump, Maybe ground somewhere?, The relay has been swapped with a known good relay, test lighted the selector switch, but seems just fine, good bright light on each tank selection, inertia switch is good, fuse is good.... It's just the front tank.. I'm hoping I don't have to drop the tank again, but I need to get this fixed...
I'm not sure how to voltage test the pump, but would appreciate if someone to let me know how to check this..
There is no transfer between tanks, no kinks or cracks or pinholes that I could find in the fuel lines..

I'm assuming just bad voltage to the pump, but I could be missing a step or overlooking something, hopefully simple. All the wire connections from the tank to the wiring harness seem to be snug and good.

Thanks in advance for the help!
Michael

 

Sounds to me like you changed out the wrong Fuel Delivery Module (FDM).
The back one was the bad one.

 

There have been reports that some times the color codes don't match on replacement pumps & they are either inop or running backwards.

I've no personal experience in this, just an observation.

 

Why would the truck still run just fine when on the rear pump if it was bad? Is there a way I can test the pump without dropping the rear tank or removing the bed?

Thanks

 

I've read that too when replacing the whole assembly, but I did just the pump itself.. maybe should have done the whole assembly. I just had to connect a black and red wire between the tanks and sender assembly inside the tank.

 

Because if the high pressure check valve is bad in the FDM in the back tank it will work just fine as the valve is open while it is pumping. But when you run the from pump it can not build up any pressure because the rear tanks check valve is open so it is quiet. You can not start the engine so you will not notice the fuel transfer.

This is why if you take it to a Ford dealer they will change both fuel assemblies to make sure they get it right with no come backs.

As long as you connected red to red and black to black you should be OK. The reverses I have read about are wiring out side the tank as some replacements have different number of wires and require an adapter.

 

Well, I guess I'll be dropping the rear tank after work one of these days...

Is there a way to test the pump I removed from the front tank? I might keep it for a backup/spare if it's still good.

Thanks,
Michael