I have a 1994 F-150 4.9L E4OD and I recently put it back together after replacing the head. I took it for its first test drive last night, and it started out somewhat ok and then completely died on me. When I first started driving, I noticed that whenever I would hit the gas, it would cut out for maybe half a second and then rev up like it’s supposed to, I figured this was the TPS sensor as it had been giving me slight issues ever since I bought the truck. But as I kept driving, that stumble kept getting worse and worse. I drove to the gas station, and then when I left the truck started completely freaking out. My check engine light kept flashing erratically as if it were a bulb with a loose connection, and whenever it came on I basically lost all ignition and it would dump fuel into the motor and choke itself out. I also lost all transmission signal, when in drive it was permanently stuck in fourth and I could only get it to downshift by putting it in either first or second, but I believe both positions engaged second for some reason. The overdrive switch also did absolutely nothing when the check engine light came on, but the reason why I thought computer was because when I initially turned the key to RUN, the fuel pump would cycle as normal, but then the relay would click off and it would still continue running, which I have heard is a sign of a failing EEC. The truck does not even start now as it is just dumping fuel in, and I’m at a complete loss if it’s not the computer.

 

It's pretty easy to pull the computer out, remove the lid, and inspect it for leaking capacitors or a corroded circuit board. I would also try to clean up the 3 ECU grounds; one near the battery, one near the driver side headlight, and one by the driver side hood hinge.

 

Capacitors had leaked out, I replaced the computer with a spare I found. I am still having the hesitation issue though, but everything else has been fixed.

 

Thank you for the follow up. Many times we never know how the story ends.

 

Check your spare computer for leaking capacitors.
Hesitation can be caused by low fuel pressure or vacuum leak.

 

+ one for that
Even the repaired ones are not foolproof
For instance
My repaired one still glitches out once in a blue moon

 

I ran codes and all I got out of it was code 116 for “Coolant Temperature Higher or Lower Than Expected” so I’m very confused. The new computer was also not remanufactured, it was out of a truck I parted out not that long ago and it was running and driving perfectly fine when it was still together. The hesitation is bad enough that if I rapidly tap the gas, it will lower the RPMs more and more until it basically stalls, and it will also occasionally start firing on what sounds like 2 random cylinders and puff a ton of unburnt fuel out the exhaust and choke itself out. And when this happens and the truck stalls, I have to crank it forever before it starts sputtering back to life again. I’m honestly ready to throw in the towel and just sell it, it smells like it might be burning antifreeze as well and I really just don’t have the money to fix this thing right now.

 

If you perform a KOEO test with a cold engine, you'll get code 116, plus a few others. You need to let the engine warm up to about 140 degrees before performing a KOEO.
I would.start with the basics.
1.Engine timing.
2.Fuel pressure.
3.Vacuum leaks.
4.Check the resistance of your ECT, ACT, and TPS with an ohm meter.
5.Clean your engine compartment grounds.

 

Good advice
Put a vacuum gauge on the motor and see what the vacuum does when you hit the gas
On a engine with no exhaust restriction and the correct fuel pressure, the vacuum gauge will drop to zero momentarily when you floor it. It will then it will build right back up
If your vacuum gauge hangs at 5 or 8 inches or less, still floored, you have restricted exhaust or low fuel pressure

 

KOEO test was ran while truck was at operating temp after driving it around. All electronics and sensors are original to the truck which had been running perfectly before I worked on it. I will have to check at some point everything but.

 

If it was indeed warmed up during the self test, it's time to run through the pinpoint tests for code 116
i can post those if you want