1993 f150 5.8l e4od
This had happened twice in the least week. Come to a stop, idling fine, and as soon as I lift my foot off the brake pedal to hut the gas it stalls. Hard to turn back over after, and it keeps stalling again and again until I rev it high in neutral.
It has a new fuel filter, coil, cap and rotor and the timing was just adjusted. (All of these between the first and second time this happened

 

Have you pulled your codes?

Fuel Injection Technical Library » How To Run a Self-Test

You have a computer-controlled engine, so ask the computer what it thinks is happening. Even if there isn't a light in the dash alerting you to a problem, there's a good chance it has a good idea of what's going on.

 

Pulled codes with a reader from oreilly
Koeo
565-canister purge
koer
538-the link you gave says insufficient rpm change/operator error, the machine said that and(trucks only)cylinder imbalance

 

The KOER test, to do it properly, has you 1) stepping on the brake and turning the steering wheel a quarter turn (or so), then 2) goosing the throttle pedal. The system should prompt you (with a rapid-succession blink at the start of the test) I believe - at least it prompts you when jumping the wires and counting dash-light blinks. I have never pulled codes with a code reader but the operational test is still the same, just don't know how (or if) a code reader would prompt you to "do your part now."

If you don't do that stuff, the Operator Error code is expected.

The Canister Purge is part of the Evaporative Emissions System... in normal operation, gasoline fumes are collected and stored in a charcoal canister and are later released into the combustion chambers via the purge valve.

I really doubt any of that stuff the computer is listing is related to your stalling problem, though, and would begin focusing on the fuel delivery & ignition. You can measure the pressure & output flow rate at the engine, you can make sure all fuel pumps are working, you can take your ignition's TFI module to a parts store to have it checked (although heat-related failures can be hard to detect). You say it's hard to crank the engine afterwards, I'm going to assume the engine is up to operating temperature, a hard-crank-on-hot-engine scenario can be caused by the ignition module not retarding the timing with the key in START.

 

Thanks for the quick reply. The code reader did prompt for those actions, and I followed as closely as I could. Ran it twice and for the same response. Both times this happened I was less than a mile away from home, so I was close to but not at operating temps.
As far as the ignition system, I just ran through IT over the last few days trying to disclose a no-start issue that ended up being my fault, I didn't check the tfi though, I will do that ASAP

It is slow to start cold normally, but very quick to start warm.

I don't know if it's related, but I believe my vss is on the way out (shaky speedometer) which I've heard can cause transmission issues.

 

Yeah, as can a faulty speedometer head. A guy in one of the other forums spent a month locating that problem on his.

 

a couple quick things to add, don't know if they're relevant or not...
first is the truck runs and drives fine apart from this and the shaky speedometer
second is strange (to me at least), when this happened today, i put on my hazards, when i got it started, i drove a couple blocks before turning them off, and i noticed the ABS light was on, and it turned off the instant i turned off the hazards.
like i said, no idea if either is related.

on my drive home from work today i tried to recreate the problem by pressing the gas harder and softer and with more or less pause between foot off the brake and foot on the gas. didn't get it to stall, but when it was still cold it seemed to dip in idle a little if i got to the gas before the truck started to roll from taking my foot off the brake.

talked to oreilly, they have the box to test the TFI, but nobody there knew how to use it or where the cables were, so i won't be able to get it checked out until tuesday, most likely.

 

Read this thread, there is some stuff near the end about a failing speedometer head caused his engine to freak out.

https://www.ford-trucks.com/forums/1...n-86-f350.html

 

Its auto could it be torque converter going bad

 

On the tfi, I was reading another thread about the black versus gray version, which should I have? And I will check on that other thread, thanks

 

I don't know, look at what you have right now?

 

i have the gray, and the reason i ask is that they are physically interchangeable, but will cause issues, including stalling if swapped. i've found that the '92 uses gray and the '94 buses black.... i'll continue searching.

1993 uses gray, thought that was a longshot, but easy enough to check

 

I would put the VIN into fordparts.com and look up the part there. Whether it will show gray vs black I really don't know, but it should give you the part number and the Motorcraft equivalent number and you can search around for prices.

 

numbers are in!
firstly, took the TFI to autozone (truck stalled in their parking lot, ironically enough) they tested it 4 times consecutively and got all green lights.

second, picked up a fuel pressure guage while i was there. ran some quick tests just now, and i think the fuel system is the problem.

key on engine off, hear the pump prime. zero PSI.
at idle, 32 psi
turn off, drops straight to zero PSI.

it was suggested that i test stop the return line up and test the pressure again to see if it's the pump check valve. two questions, possibly both dumb.
first, how do i locate the return line?
second, i'm guessing i just do this koeo, and do not attempt to run the truck in this state, is that accurate?

 

one more quick question, the guy at autozone suggested if there was excessive pressure loss it might be from the fuel pump check valve. is this a replaceable part or is it part of the fuel pump assembly?
oreilly doesn't list a part that i can find, and chilton doesn't have a description of it as a separate part or as a function of the fuel pump assembly.