My 1994 F-150 302 5 speed would intermittingly idle rough, loping when driving and blowing thick black smoke. Could not find the problem. Next day it may run great,or may still run rough. Because I got code 23, 32, 33, I checked the TPS, EGR,EVP, and MAP – all tested good. All the spark plugs are black. I cleaned gapped and reinstalled until I get it fixed. Had 15”of steady vacuum when it first started running bad, has now dropped to 12 when running rough – almost stalling. It seems to be getting progressively worse as I could not even get it started today, even with starting fluid. I have spark at the plugs. When I shut it down 2 days ago, I did it with the inertia switch shut off. It seemed to run much smoother within 2 sec to 10sec then it ran out of fuel. After seeing it run smooth as the fuel pressure came down I installed a new Fuel pressure regulator today. Reset the inertia switch and had hope – but again no start, I even tried some starting fluid. I held the pedal to the floor but it did not help. It sounds like the fuel pump is running all the time. It seems to be loaded with gasoline; the dip stick even smells like gas. I have been working on this since early Dec. I’m lost and going in circles, and need the truck as a tree feel on my shed and roof a week ago when a cold front came through. Any comments on where to go from here would be appreciated – Thanks<o></o>

 

Sounds like a bad PCM computer.
Any time the fuel pumps run all the time with the key on and the engine not running it is more than likely the PCM computer.

 

X2

 

X3. Sounds like the computer is overfueling it. There's a few malfunctions that can cause this, but the fact that your fuel pumps are running continuously also points to a bad EEC (computer).

 

Thanks to all.<o></o

That’s 3 for a new computer. What are the “few other malfunctions that cause this”? Truck only gets driven every 2 weeks and about 350-500 miles per year. It’s very humid here in N. Fla. in the woods. Strange part is that it started with the engine light on, but no effect on the way it ran. When it started to mess up it would be instant, from good to bad and sometimes flip back to good without shutting it down. Then it went to running bad about 2-3 miles down the road and stayed that way to shut down. Next day it would be ok rinse and repeat. Then it ran very rough with a weird sound like high bass sounding wind at your window in the winter. Higher the rpm louder the sound, rev It up and it sounded like an air horn in the distance and would do that when it was running smooth too, free rev or under load. Checked several connectors and they were call clean. Spark plugs were black, clean them and reinstalled. Ran great, tested it going slow, fast, bonzi run and bumping dirt road, still ran great after 20 mile test run. Thought it was fixed, just a connector or something. Next time I used it I got 5 miles down the road and it hit again very rough, next day I had to use starting fluid to get it started. When I got it started, ran really rough, smoking like a freight train. That’s when I flipped the inertia switch to kill the fuel pump and it started to run smoother just before it ran out of gas. So I changed the fuel pressure regulator thinking I had over pressure, and hopefully had finally found the problem. I have not been able to get it started since then, even with starting fluid. Checked the spark at a plug and it is working. I did reset the inertia switch. Hard to believe it want even sputter with spark and starting fluid. Tomorrow I am going to check the fuel pump and power control system relays – maybe one of the contacts have welded together?<o></o

New Note:<o></o

WOW- Just seen a new problem - #2 cylinder injector has a chewed wire from a field mouse – there every where here. It is not broken in two just chewed on. I can barely get my fingers under the manifold, but I feel wire sticking my fingers. Could a broken lead to an injector be causing all of this? Would it cause all the injectors to be out of sequence (read somewhere that the FI system is a bank type) or short the EEC. It is not touching anything to short it to ground. A tow truck may be my next move before buying a $250 EEC if I can’t get it started. <o></o

 

You've been given some sage advise above.

Here's some reading for you.
Click this link: A9x ECM's (and same years ECM's) Failures Due to Age

If your computer/ECM is failing, it has nothing to do with "Truck only gets driven every 2 weeks and about 350-500 miles per year.".

The capacitors on the circuit board (in the computer) will fail due to age and can/will leak their electrolyte on to neighboring circuits causing all kinds of mayhem and driveability problems.

Take the time to remove the computer from your truck and open it up.
You'll most likely find a/some leaking capacitors on the circuit board.
If you catch the leaking capacitors early, and if you're handy with a soldering iron, the repair will take about 30 minutes to do and cost less than ten bucks.

Been there done that as many others here have too.

Bob