So like I said, my 98 Ram 1500 w/ 5.9 just quit running going down the freeway one morning. Acted like it wasn't getting fuel (bogged out), it did idled roughly so I shut it down took a quick peek around engine compartment to see if anything came loose, nothing. Started it, still idled rough, shut it down again, cursed at it and tried it again, ran like nothing was wrong? Took back off and about half way to my job from there did same thing, just chugging and sputtering, managed to get to work and figured something either clogged fuel filter or pump went bad. Tried firing it up at lunch and it acted like it was running on about 3 cylinders. Trailered it home and changed fuel pump because I figured that's what it was. Wrong nothing changed except now it wouldn't even run rough, would almost start if I hold pedal to floor. So I figured maybe coil went bad, changed that and cap and rotor, still the same. Tested TPS and Mass Air Flow sensor, both tested ok, listened to injectors, clicking fine, put inline spark detector from coil to distributor, gets spark but was red? in tester. Also remembered I had a fuel gauge so I check the rail pressure, its good. Tried testing crank and cam sensors but not sure I had it right, stupid Haynes manual wire color codes are all wrong. Check the ASR and fuel pump relays also. Looked for loose grounds also. Everything seems to check out, PCM is all that's left and would kind of make sense, am I looking in the right direction? ANY IDEAS would be greatly appreciated.

 

Have a scanner available that can read data? Need to see what the PCM thinks engine temp is. If the ect sensor fails open, the PCM thinks its -40 degrees, and positively DUMPS fuel into the cylinders...... however, when you hold the gas pedal to the floor, it puts the PCM in 'clear flood' mode, and it drastically cuts back on fuel...... Sensor is just to the drivers side of the thermostat housing on the engine....... Fun to get to....

 

I don't have a scanner, must be a test I can do to ect sensor, maybe it took a crap. Also noticed when I pulled plugs there pretty carboned up and seem to have weak spark, not a crisp blue like I would expect but red.

 

If you're showing a weak spark, the ignition coil may be going bad. I'd spend some time cleaning up the spark before chasing anything else.

 

Well it has a new coil, cap and rotor (that was my second guess after fuel pump). Went a got a scanner, only code was for ASD relay ( which I had out and tried starting so not surprising) cleared it, tried to fire it up and see if any codes jumped up, nothing. I believe this scanner shows live engine stuff, will have to read instructions I guess. It will almost try to start but if I have a weak spark...I have no idea why it does and would that cause it to just die going down the road?

 

How old are the wires, especially the coil wire?