To start I apologize if this thread is long, but I believe I should be thorough. I own a 94 Ram 1500 2WD Automatic with the 318. I have been searching all over this forum as a non-member, but finally decided to create a post of my own as I can not find a source of my problem.

Work done so far:
Lower intake, plenum, and throttle body gaskets
Full Tune-Up
Fuel Pump
EGR Delete (The egr tube was too much of a pain to deal with)
Vacuum Lines Plugged/Replaced
**The truck ran the exact same way before any of these were performed

Current Codes Set:
12 - Direct battery input to PCM was disconnected within the last 50 key-on cycles (Always on since purchase, but I've had the battery disconnected quite a few times.)

17 - Closed loop temp not reached or engine cold too long (This code is very recent and the truck was acting up beforehand. I believe to be the sender for the PCM, as my gauge shows normal, but haven't had the time to look into it.)

32 - EGR system failure (EGR Delete)

37 - Torque converter clutch solenoid CKT or park/neutral switch failure (Truck fails to start in park at times, and the torque converter whines. Was told the tranny only had 7k on it when I got the truck... well, who knows right.)






The truck is hard to start after sitting for a few hours, but sometimes cranks up on a dime. It originally was sluggish feeling and started stalling out while coming to a stop. I did the tune up and intake gaskets knowing they were a common problem, but has slowly gotten much worse. The truck will now shut off while even going down the highway at 60mph, and stalls constantly in traffic. It use to fire right up, but now I contemplate if it has finally kicked the bucket as the engine turns enough revolutions to travel the globe before finally starting back up again. This previous weekend I was hauling a light load in the bed and on a trailer down I-75 (No more than 1000lbs combined). On the way the truck had absolutely no power as soon as I hit O/D. It would actually lose speed causing me to put the pedal down and get the truck to downshift. Once I would get back up to cruising speed (80mph) the truck would once again lose speed and begin back firing at 65mph+, once shooting a cloud of black smoke. It would only straighten back out if managed to get it to downshift back to 3rd while WOT.

Having my guesses, I hooked my fuel pressure gauge up once I got to my destination to find I had 35psi at idle. Watching the gauge taped to my windshield (don't judge me) it would drop to 30psi under a load. So, I went the next day and bought a new pump assembly. I also had to buy a quick release retainer because the previous owner had the line ziptied to the regulator housing. After installation I checked the PSI again and I had 40 at idle. I thought it was fixed. NOPE. After 5 miles or less down the highway on a test drive the truck shut off at 65mph. I gave up and went to bed for the night. The next day leaving work I realized my pressure had climbed to 45psi at idle. Thinking the regulator may be bad on my new assembly, as I read these truck should be around 39psi. Well, it gets worse. Now, the gauge will bounce between 40-50psi rapidly if in park and holding a steady RPM with the throttle. It will also bounce between 30-50PSI while in gear, break pressed, and under a load. I was worried about the pressure spike. Well, a few hours ago I delivered some parts I had for sale, and upon parking the truck the quick release on the assembly blew off. Scared the s!@t out of me! There was fuel everywhere. I snapped it back on, and it held the rest of the 45 minute drive home. The truck does not back fire or bog down in O/D as it did before the new pump. However, upon testing for leak down, I will lose 10psi in under a minute with the key off. I figured it could be an injector issue, but am currently waiting on new o-rings before I pull them for inspection. I don't know if anything else could be causing my fuel pressure issue at this point besides the injectors or just a faulty pump.

I have ignition from the dist. when the truck is hard to start, and from the times I've been able to see the gauge, fuel as well. When it stalls, it is instantaneous, as if flipping a light switch. This thing has almost gotten me beat. I heard that the front O2 on these could be bad without setting a code causing this, but I can not find a scanner or adapter to read live data off this thing. A leaking injector(s) is possible I guess, but with how random the issue can be, and high fuel rail pressure, I am not sure. The PCM could also be an issue by chance. I have not performed a compression test, as my gauge has went missing after loaning it. I'm just really looking for some insight on someone who knows more than me in hopes of ending this wild goose chase. I work 6 days a week, and it is hard to check everything within reasonable time. I've tried to be as thorough as possible. If I have missed anything important I will update it, or if you need anymore info let me know.

 

From the description I'd say fuel pressure is a red herring. Pressure is supposed to be "approximately 241-310 kPa (35-45 psi)". 30-50 psi is not that far off and I doubt it would cause stalling issues. Backfiring and black cloud of smoke means there was fuel to burn. Stalling/shutting off would make me look into crank and cam position sensors or maybe the auto shutdown relay. Troubleshooting pre ODBII models is unfortunately a PITA. The crank/cam sensors can be checked with a scope but that's not a typical home mechanic tool. Either throw parts at it and hope for the best or find a shop that deals with older vehicles.

 

Thanks for the response. I agree, the fuel pressue issue could have me side tracked from the root of the problem. My initial thought when I saw the smoke was off timing, but it drives so well up to 4th that I didn't think much of it. Do you know of any good scanners that would run live data off these old things? I regret getting rid of my Solus everyday. If it were OBDII I'd just hook my laptop to it, but I'm not sure if any of my software would support it even if I found an adapter.

 

17 - Closed loop temp not reached or engine cold too long

This one. I rarely see this code come up on an OBDI PCM. If your temp gauge is telling you the engine is indeed coming up to temp, then this bears some investigation. Your truck has TWO temp sensors. One for the gauge in the dash, and one for the PCM. The sensor for the PCM is a two wire sensor, and it should be just to the drivers side of the thermostat housing. (yeah, it's fun to get to.)

 

ECTS for the PCM is on my checklist for tonight. Though it may have been bad before it threw the code, it wasn't operating correctly beforehand either.

 

Yeah, the PCM really has no clue if the ECT is actually working properly. Nothing to compare it to.

 

I know. All the PCM sees is either in or out of a certain range of voltage. I can back probe the sensor and test it. If not working properly I will replace. If the PCM gets correct signal or is not sending voltage to the sender then I know it's different. I don't like wasting money. No matter how little a new one may cost.

 

Found something interesting! I noticed when the truck started to shut off, and I gave it gas to keep it alive, the CEL on the dash would turn off for a blink of an eye. I thought, wow, might be a wiring, or PCM issue afterall.

Well, upon checking the ECTS wiring at the PCM harness, I found that I only have 3.9v on pin 2 of the connector, which is the tan and black wire. It is suppose to have 5v with key on. I performed a continuity test across the IAT connector and pin 16 on the PCM connector. It checked out to be fine. There is no corrosion on either the connector or PCM itself.
Reference to my continuity test: http://dodgeram.info/Engine-Gas/OBDI/Fault-22.htm

Your thoughts? Could it be something else in the wiring, or am I just looking at a bad PCM?

*Also the resistance of the temp sensor itself checked out fine.

 

Check some of the other 5 volt sensors, and see if they are actually getting five volts. Might just be a bad connection somewhere. (several splices in that circuit.)

 

Good idea. Will update tonight. I checked my grounds last night, and there seems to be no issue, but I'll clean them all just to be safe as well.

**I also want to add that on the way to work this morning the truck started sounding like it was popping/backfiring through the intake and would not go above 2k rpm. As I let off the gas it straightened out and drove fine. It is as if timing is definately getting out of sync, or the advance is not being adjusted correctly.