It doesn't, the leak is in the rear tank Fuel Delivery Module. There's a shuttle valve in there so when the fuel line is pressurized by the front pump the fuel won't fill the rear tank. This valve along with the rear pump itself are bad, so replacing the rear FDM will fix both problems at once!

 

^^^ What he said. Commonly known as the Fuel Crossflow problem. There was a recall and extended recall for this on some trucks, but you're probably way past the window on this. Ford's fix was to install an inline check valve on the supply line to prevent backflow when the other tank's pump was energized. (That's how they fixed mine, anyway, but both my pumps were otherwise good).

Jason

 

I actually replaced the rear pump/tank about two years ago and removed that recall check valve because i didnt know what it was. Can i add in my own check valve after i replace the pump just for insurance?

 

Sure you can add your own check valve, as long as it's rated for contact with gasoline and can handle the pressure. Just add the recall check valve back that you removed, if you still have it.

Might as well do it on both FDM's.

 

I definitely dont have it lol. Cant i sneak one anywhere in the fuel line? Or does it have to have those retarded quick release fittings on it?

 

Have you checked the ignition timing? Since you said it happened all at once, I would be suspicious that the distributor moved, or your timing chain jumped. Your symptoms are consistent with both.

 

4.9's have timing gears.

But, there is the possibility that the spout connector may have fallen out/been misplaced !!!

Bob

 

No idea where to get one (I kept mine after I changed the pump, just in case) to add to the line, but here's a check valve.

Ford's lil Band-Aid fix.



As you can see, snaps right on the fuel pump nipple, and then the fuel line snaps onto it.

No muss, no fuss.



One end.


The other end.