I am having problems with my 1989 ford f250 4.9l(140000 or 240000 miles) . In the past the front tank would only work on the highway, if I would let off the gas on the highway it would sputter and die. I finally got around to replacing the fuel pump (napa part number NFP P74518S) in the front tank 3 weeks ago. I took it for a test drive and filled up the front tank to full. I got about a mile from my house and it died and would not start. I came back the next day and it started right back up. I assumed that I got some air in the system. That was 3 weeks ago and everything seemed fine, ive been driving it this whole time with no problems, just using the rear tank fearung i might get stranded again. I have been switching to the front tank for a few seconds every now and again. Now I am having the cross flow problem where when I take off the gas cap to the front tank gas starts pouring out. I guess it is possible that the new fuel pump is defective or whatever fuel pump was in there was the wrong one to begin with. Also I just saw looking at o’reilly website that it appears that there is a 19 gallon and a 17 gallon fuel pump, but the one I pulled out looks just like the one I replaced it with. Napa only sells the 19 gallon one. What do you suggest I do next? i would like to figure out what is wrong and not just patch the problem with check valves. Any and all help would be much appreciated. Thanks in advance.

 

On your truck fuel flow from the tanks is controlled by a device on the frame called the dual function resovoir, this is the likely source of your crossflow problem. It's also likely you got a bum fuel pump for the front tank, these things have a terrible track record so unless you want to be replacing it every other week you may want to consider buying an OEM pump, others may be able to suggest a different aftermarket pump that lasts.

 

NHTSA Campaign Number:
91V146000
Component:
FUEL SYSTEM, GASOLINE:STORAGE:AUXILLARY TANK:SELECTOR DEVICES
Manufacturer Involved:
FORD MOTOR COMPANY
Manufacturing Start Date:
Wed, 02/01/1989
Manufacturing End Date:
Fri, 02/01/1991
Potential Number of Units Affected:
350000
Defect Summary:
THE DUAL FUEL TANK SELECTOR VALVE MAY MALFUNCTION AND CAUSE AN OVERFILL CONDITION IN ONE OF THE FUEL TANKS, RESULTING IN AN OVERFLOW OF FUEL PAST THE FILLER CAP.
Consequence Summary:
THE OVERFLOW OF FUEL PAST THE FILLER CAP CAUSES A FUEL LEAKAGE, WHICH CAN RESULT IN A FIRE WHEN EXPOSED TO A SOURCE OF IGNITION.
Corrective Summary:
REPLACE THE DUAL FUEL TANK SELECTOR VALVE.

 

I'm definitely filing a complaint and I hope that anyone else that has had this problem also files a complaint. This appears to be a fairly common problem that could have easily been disastrous.