My 92 f150 with the 5.0 is throwing me for a fit. Love her too death but like the ex wife some times she needs a good swift kick in the pants to get her right. The problem I've been having is when it's a cold start she starts and runs fine but then I can drive about 2 miles down the road to the gas station and when I come back out it cranks a good 5 to 7 seconds before it kicks off and starts. Now so far I have looked at the following: changed the coolant temp sensor to the computer, checked coil, checked tfi module, checked pip signal to module (normally shows.04 volts but will switch up to 4.5 to 5 volts when cranking, checked fuel pressure at the rail when cranking (sits around 40psi), new starter as well. Bought it years back, did the normal tune up of cap, rotor, and plugs and wires then it started doing this before I got my second truck so I parked it for a few years. Here in the past year I put her back on the road and the issue had gone away but here recently it's come back again. Also I tried ruling out a vacuum leak by plugging any likes that aren't necessary as far as the running of the truck. So after a few weeks of testing, retesting, using holy water and even a priest for the typical exorcism, I am going to the hive mind to see if anyone out there in the interwebs might have an idea of where to look now, or at the very least know if a better priest than I do.

 

The only thing that comes to mind is the timing, be sure to pull the spout before checking.

 

Timing chain and gear were replaced when I got it for the fact I didn't want it to jump time while having over 200 thousand miles already.

 

Also if it was timing I don't see it doing it only after it's ran awhile but not do it when it's been sitting overnight or even for several hours.

 

What controls the cold start for this truck? I know in the days of carburators it was the choke that did it. I'm wondering if when it's cold the cold start is working but after it warms up there cold start is still trying to act like it's cold. Any ideas?

 

The computer


Warm up the truck then do this: How to run a Self Test

List the codes by number and when they were displayed, i.e. Key On Engine Off (KOEO) tests or Stored Codes (aka CM) display. Your truck could display two or three digit codes. Never both, it's two OR three.


You stated you checked the fuel pressure, but was it 40 +/- when cranking for the long period of time?

What is it when first cycling the key from Off to Run when cold?

What is it when first cycling the key from Off to Run when warm?

 

I tested the pressure once when it was cold and then again after I had came back from driving one day, both times put it around 40 psi, I was also looking at fuel being the issue before but with it not dropping off during cranking I figured that might not be the issue. I'm not saying it's not worth a second check though just to make sure. I would have checked for codes but my check engine light is burnt out so I'll have to see if I have another one to swap in for the self test. During a cold start situation I know the computer is controlling it but what is it changing for the cold starts? IAC valve? Injectors?

 

Could be too much fuel if you have an injector(s) leaking. Another test is see how quickly the fuel pressure drops after shutting off the key/engine.

Cold Start Strategy from Ryan:

Start / Crank
This is the start (I know, bad joke). The EEC needs to senses several things to start an engine:
* Power to EEC and fuel pump(s)
* Slow and irregular PIP signal from the distributor
* MAF/MAP low and irregular
* TPS is closed
* HEGO shows leanThese tell the EEC that you have just checked the dash, want the engine to start, and have turned the key. Even though you've heard the fuel pumps whirr, the injectors haven't released any fuel until it senses engine rotation. Even when the engine does turn over EEC hesitates almost a full second to begin fuel and spark; this is to support oil lubrication. ECT and ACT determine the amount of fuel; the colder it is the more fuel it dumps in. The Idle Air Bypass is opened 100% to allow for operator error free starting. Spark control is taken over by the TFI, as long as you hold the key in the start position. What if things go bad, your ignition system could not light the engine, and it become flooded? Press the accelerator to the floor while starting, the full open TPS reading will tell the EEC to cut the injectors back to almost nothing. When you decide the fuel has been flushed out release the pedal and the EEC will fire the injectors and the engine fires up. Once the key springs into run, timing is determined by ECT and ACT, the PIP steadies out, the MAF/MAP builds, and the system bumps into the next strategy.

 

Would a 92 Ford have an act sensor?

 

Ok so an update so far. I have found that when I press the accelerator to the floor before starting it it starts right away. I know this turns off the injectors to clear it out so it seems that there is a leaking fuel issue from the injectors? Everything so far has checked out for air, fuel, and spark. How would one check for leaking injectors?

 

And the temp sensor is new, the air temp sensor was dirty so I cleaned it out, still fights to start after it has really awhile.