So I had my front fuel pump replaced on my 96 F150 the other day and it seems to run great now. But now I have a new problem.I had a half tank of gas in the front tank and since its cold I started it to warm it up for 10min before leaving work,when I came outside the pickup had quit and the front tank was now empty with gas all over the ground. It had been pouring out the fill spout on the rear tank. What would cause it to do this? Is it something the shop could have done or just a coincident something else went wrong? Could having the vent lines on top of the tank switched around cause it for some reason? Thanks

 

It could be just a matter of coincidence that the rear tank Fuel Delivery Module has gone bad after the front FDM was replaced but I would take it back to the shop that did the work. This vintage Ford is well known to exhibit the fuel tank cross-flow problem at any time.

 

Before this I had the common rear tank slowly filled the front. Now they probably fill each other no matter what tank im on.

 

There is a check valve at each pump and your rear one is either shot or has some debris in it. probably have to pull off your rear tank to fix.

 

From my experience and those on the site, the tank that is overfilling is always the problem. I would replace that pump now and it will probably fix the problem.

 

Yeah the new pump may have overwhelmed the check valve in the other pump.