Here's the scoop for a 1996 Ford F150 4x4 problems:
(continuing saga) This vehicle is a cross-over or year change-over - '97 and up were a different vehicle.
I had this truck checked at an emissions station. When they finished all of the tests, I was told the truck was using gas at three times the max limit; and it does run very rich. So I took the "beast" home, looked in the manual for the data hookup block(OBDI). According to the manual, there is a hookup under the hood. Well,I never found it. I did, however, find a data block under the dash just right of the hump. So I hooked up the
OBDI, and received the following two error codes:

P0743 - Torque converter circuit not working
P0401 - EGR flow insufficient

Nothing directly gas related (we're talking fuel injection). The torque converter message is related to the electronic overdrive; 4th gear if you will.
The EGR flow message I can only speculate. The cats could be dead, or the message may be related to the muffler being separated from the exhaust pipe; very little back pressure.
So I have some (very little) understanding of these two codes. But they don't explain the high gas consumption. I've replaced the fuel filter, new plugs, replaced both O2 sensors, thermostat, cleaned the air flow sensor, checked the throttle cable, and replaced two other sensors. I've also checked the fuel injectors on the drivers' side, and their opening and closing. I haven't done the passengers' side yet due to the intake manifold interference.
So, my fellow motorheads, is there another Data link connector under the hood, and/or do I place a jumper wire in the connector under the dash? What is your take as to why there's a high consumption of fuel? Is there a fuel injection regulator(s) that control things? Any help would be appreciated.

 

Lets start with what I remember reading in your thread. What are the readings of the emissions test. The readings will help us help you.

Yes there is a fuel pressure regulator, and unless the diaphram is ruptured, I doubt if it is your problem.

The PO401 code could be the DPFE sensor, Ford had problems with them going bad or miss manufactured.

 

A 96 shouldn't be a OBI It should be a OBII system so it should have the data hook-up inside the cab not under the hood.

 

Well gentlemen, I read the posts and here's the next round of response. First, I'm unable to find the emissions report, and may, in fact, have thrown it away. But I'll keep looking to see if it's stashed somewhere.

As to the post stating the system is an OBII, it begs the question, "Do I still need to use a jumper wire and Volt meter to retrieve codes, or will the OBII capture them?

(Back to looking for the emission sheet.)