I have a 1996 Ram B2500 van with 99,000 miles. It has been the most reliable vehicle I have ever owned up until recently. Now when traveling long distance, usually around 150 miles, it will begin to loose power with allot of misfiring. One mechanic described the noise, which I thought was pretty funny, like farting in a bucket! If you continue to drive, it will continue to loose more and more power until you can only go about 20 mph with continuous backfiring. The engine light is steady at times and flashes other times. Then if you shut off motor for about a half hour it will start and run completely normal the rest of the trip. I have had 3 different garages work on it and no one can fix it. So far they have done a complete tune-up, replaced the ECM, pickup coil, ICM and crankshaft position sensor. Engine code indicate misfires on all cylinders. Anyone have any ideas?

 

Check the resistance or just replace the 2 wire Coolant Temp Sensor on the intake manifold.

Clean the battery to engine ground, battery to frame/ firewall ground. Frame to engine ground, and add one if you cannot find one.

Make sure the battery cables and battery are in good condition.

See if you can read any AC electricity in the Battery charging circuit. If a diode has failed in the alternator it will still charge at 66% of it's capacity, but also send AC electricity through the DC system and can mess things up.

Some members report the use of an inverter while underway causes electrical interference that causes symptoms similar to what you describe.

 

Your fuel pump is overheating and shutting down.

 

Could also be your catalytic converter.

Have it checked too...Makes a TON of racket and lost power like you wouldn't believe...

 

Exactly what happened to my '95 5.2. Only additional symptom was hard starting when hot and would start troubles after driving 10-20mi at speed. Originally thought was fuel pressure regulator. This perplexed many techs and none could find the problem. However no one thought to check the fuel pressure will driving. When problem started fuel pressure dropped to below 30# occasionally to 20#. Replacement pump assy saved the day.

 

Thank you all for your help, I'm going to take this information to the mechanic and go from there. I will report back later with the outcome. Thanks again!!

 

It was the fuel pump causing the problem, the van is running like a champ again. Thanks again to all, especially alloro and bogp40!!!!