Wits end 1992 Dodge D150

[tsubaki]

5.2L, MPFI & automatic transmission.
I've been beating my head on this vehicle on and off for 5 years. After letting it sit for the last 2 years I figured I'd attempt to find the problem AGAIN.
In the past the truck would crank up and run flawlessly but at some point it will shut off and not restart, having to be wreckered in. It might sit up and then by some miracle start running fine or even replacing a part might make it run fine only to be wreckered back in.
NOW, it will crank up and run for several seconds, then shut off and not restart. After that if the key is left in the on position the coil stays energized and the injectors appear to be spraying fuel into the cylinders.
The reason I say this is I removed the coil wire and attached another coil wire with a spark plug on the other end, it would jump a continuous arc for 2 inches to anything it can ground to. I also drained the crankcase of 9 quarts of fuel.
This has been going on all along but I couldn't get the vehicle to reproduce the problem to where I could catch it.
Any Ideas??
Timing and chain appear to be good, compression stroke at TDC on mark. Fuel has been drained and replaced.
This is a list of replaced parts (somewhat it order) from the last 5 years with probably less than 500 miles of operation trying to find this problem. Other minor things also have been replaced.
Distributor ignition pickup
Crankshaft position sensor
Powertrain control module
Fuel pump
Auto shutdown relay / fuel pump relay
Ignition switch
Idle air control valve
MAP sensor
Coil
Oxygen sensor
Throttle position sensor
Fuel pressure regulator
I've got over $850 just in parts, some replaced twice.
I'm way past arbitrarily replacing parts, just give me some ideas.
In reference to the above mentioned continuous arc/injector spraying situation, if I unplug the 2 wire connector to the coil and stick a test light from the battery positive to one of the wire terminals I get a very rapid pulse. This indicates to me something is signaling the injectors and coil to operate at a high frequency much like full throttle situation.

Any ideas?

[THEFERMANATOR]

Since you say the problem persisted after PCM replacement, about the only thing that comes to mind to me is a bad ground. The early SBEC is pretty basic, but normally reliable. They can be shorted out and do funky things if the crank sensor gets shorted out, but I've never heard of one firing the injectors and coil at the same time. So either you have a bad ground allowing the board to backfeed somewhere, or you got 2 bad PCM's in a row. The only other thing I could think of is a short to power on one of the sensors freaking out the PCM. I can honestly say I have never heard of a single case like this before though. The most common problems on those early trucks was shorted out crank sensors causing a no start.

[smokeonthewater]

step one unplug EVERYTHING... all sensors and fuel injectors except the coil.... see if condition persists.... If yes then you are left with bad ground, damaged harness or bad pcm (my bet it's this one) if not then start plugging things in one at a time till problem returns....

either the pcm it possessed or being fooled by outside forces

[tsubaki]

Thanks guys, I actually took a short video of the coil being possessed.
We have done numerous things in numerous sequences trying to get it to reproduce this problem, at lease we are that much closer.

A search for a bad ground began after the DIP, PCM and CPS were replaced. So far nothing. We even grounded from the battery to the block, to the frame and then to the firewall, still no difference.
We could tell during the first cession of checking wires that someone else had the same thought process.

Replacing the CPS and PCM again is not out of the question. We just replaced the DIP, distributor cap and rotor again. The distributor cap had two burned places that looked like a welding arc hit it.

Getting another book is probably going to be the next purchase as we have found several things not covered in the one we have.
I'll also see if I can get some real readings and write them down in the sequence tested.

[ssiredfish]

Can I say it? I dont wanna say it but I have to.......ITS A DODGE!!!!

Gettin rid of mine before it killed me was the best thing I ever did. I cant tell you what it feels like to have to slam on brakes and have your vehicle shutdown on you and steering lockup, meanwhile you throw it into neutral, restart, put back in gear and barely avoid the wreck.

......and thats why they call it a DODGE

[smokeonthewater]

The bad ground would be somewhere in the engine/PCM wiring.... Personally I think this is unlikely

[THEFERMANATOR]

Originally Posted by smokeonthewater

The bad ground would be somewhere in the engine/PCM wiring.... Personally I think this is unlikely

DODGE didn't have as many ground issues as GM, but they did happen. The early SBEC PCM's did fail alot though, and would do strange things if a pickup shorted out.

[tsubaki]

Well crap, I traced the ground from the negative battery post to the eyelet/body ground to a harness connection to two wires labeled as ground to the PCM.
Also along the way traced another spliced ground from the above wire to another harness connector to a diagnostic connector and to the PCM.
All these tested to be fine.

Another PCM is on order. It's really gonna piss me off if it cranks up and runs fine after replacing it.

[tsubaki]

Please let me know if the link works.
I ain't real sure about this newer photobucket.
It ain't but a 3 second video, had to edit the beginning and end due to immature language.

[smokeonthewater]

Yikes....