Having trouble with 92 Dodge Ram B250 conversion van. 318 3/4 ton rated.
As I drive anywhere the van just stalls. Drops dead right in it's tracks. Sometimes it will start right away and sometimes it takes 5 minutes. Cool or Hot it persists in dying...I have replaced the fuel filter, air filter, PVC valve, cap & rotor, coil...all with no fix! Thinking fuel system but not sure.

Little help out there please..

Ed

 

Ed
Have you checked for any store codes in the PCM?

 

First thing that I checked and no codes showing up

 

Sounds very similar to the problem I'm having with a 94 B350. These intermittent failures are maddening!!

You have to divide and conquer. First, an inexpensive thing to do is determine if the coil is delivering pulses when the van won't restart. I used a timing light, not to check engine timing but simply to detect presence of pulses.

If you have a timing light or can borrow one, permanently configure the timing light with the sensor clamped on the high voltage wire to one of the cylinders, doesn't matter which one. Run the sensor cable under the engine shroud gasket and reclamp the shroud on the cable. I have an old timing light so I ran the power cable out the driver's side doorjamb and clamped onto the battery posts. (I thought of adapting the power clips to a cigarette lighter plug but I believe power to the cigarette lighter, radio, etc. is off while the starter motor is turning over.) I had to leave the timing light laying on the dashboard. You might have a later model timing light than mine; I assume some newer ones operate from an internal battery; in that case, ignore the advice about routing the power cable.

Now, while the van is running, you have to occasionally pull the trigger on your timing light to make sure the power is still connected and the high voltage pickup is still working. When it dies and won't restart, just pull the trigger on the timing light with your left hand while you're attempting to start the engine with your right hand...... to determine if "spark" is present.

I drove around with that timing light for almost 3 weeks before the van failed and I got the answer: no spark.

Then, I configured my new oscilloscope to monitor several signals at the PCM: crank position, cam position, 8V to sensors, 8V return to sensors, ASD relay coil driver, ignition coil driver, and fuel injector #1. I couldn't monitor all these at the same time because the scope is limited to 4 channels. So, I tried various combinations of scope inputs. After collecting lots of data over a period of 2 months, I'm 99.44% certain now that the PCM's coil driver is intermittently failing. So, now I'm shopping for a PCM (~$220)

You can see some pictures of my setup and some of the data acquired at this public link:

http://www.facebook.com/media/set/?s...1&l=85d45119cc

You could also rig an array of LEDs (and diodes and resistors) to monitor the health of some of the PCM's signals. You'd need some of those insulation-piercing probes at about $7 each. Some signals that should work with LEDs: coil driver, fuel injector drivers, ASD relay driver, and 12V from the ASD contact to the coil.

Good luck, let us know if you need more advice and let us know your progress.

Jeff

 

Thank you, I'll look into the timing light use but the Ocilloscope my be a bit beyond my technical expertise. May start withe the coil driver if I can find the damn thing. I had one mechanic tell me that the ECM would be a likley candidate but cannot find it anywhere and have had several people look with me. Any idea where they might hide it on this van?


Ed

 

Meant ICM... ignition control module.

 

Lots of names for this box. Dodge calls it PCM, auto parts places call it ECM or ICM. Just adds to the confusion. )

In the 94, the PCM is in the engine compartment, mounted on the firewall (about mid-way between left and right extremes). It's an odd-shaped box, 6-sided but not a regular heaxagon. If you look at my facebook pictures showing the red insulation- piercing probes under the hood, you might be able to make out the PCM in the background if the pic's depth of field is good enough.

BTW, the timing light experiment just tells you that it's not exclusively a fuel problem. Depending on what's going on in the background, you might be losing both fuel and spark if the PCM is shutting them down by de-energizing the ASD relay. If you discover there's no spark, you have to drill deeper to see why there's no spark. I say this assuming the 92 and 94 PCMs operate very similarly; that might be a bad assumption.

I signed up for the tech data at alldatadiy.com to get schematics and functinal descriptions for the 94. That was about $25 for a year.

Jeff