RRC strange sudden highway misfire

Ccfarm5

New member
Sep 19, 2016
4
0
Columbia, MO
After about 40 minutes of highway driving in my 1994 County LWB his weekend, the engine bogged down, and started bucking and misfiring violently. I pulled off the highway in neutral to try to keep it from dying. I got it stopped and in park but it died as soon as I let off the gas. I opened the hood and heard the injectors rapidly firing. I turned the ignition off and on again, and the injectors continued to fire. I turned the ignition off and disconnected the ECM as if I was clearing any codes, and it started normally. The injectors don't fire now without the engine running. The check engine light came on during the rest of the trip home, but it cleared itself when I shut the truck off. Not sure how to start the diagnosis. Any help would be appreciated.
Thanks!
Chad Stretz
Columbia, MO
 

Flyfish

Well-known member
Oct 29, 2004
1,402
212
52
St. Louis
Lots of possibilities there. Initially sounded like a fuel pump issue so I would check your pressure. But the injector thing is different. The alternator and vss are two things to look if there’s an obvious issue,. But that’s just guessing blind trying to figure it out from one event.
 
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Ccfarm5

New member
Sep 19, 2016
4
0
Columbia, MO
Here's an update, as I finally got around to making repairs:
Yesterday I replaced the fuel pump, relocated the ignition amplifier, swapped the alternator, and installed a new coil, distributor cap, and rotor. She fired right up and runs with more pep. Still has a misfire at idle (i believe I have a sticky valve), but acceleration is great and throttle response is instant. The idle speed is a bit fast, but I'm attributing that to the ECM needing time to get used to the new components. I will drive a little farther on the highway today in the 99 degree temps and see how it does.
Chad
 

Blueboy

Well-known member
Apr 20, 2004
3,205
459
Back in the USA; Rockwood, PA
Here's an update, as I finally got around to making repairs:
Yesterday I replaced the fuel pump, relocated the ignition amplifier, swapped the alternator, and installed a new coil, distributor cap, and rotor. She fired right up and runs with more pep. Still has a misfire at idle (i believe I have a sticky valve), but acceleration is great and throttle response is instant. The idle speed is a bit fast, but I'm attributing that to the ECM needing time to get used to the new components. I will drive a little farther on the highway today in the 99 degree temps and see how it does.
Chad
There was a batch of not so good LR OEM rotors. Not sure what you used yet Powerspark is a great rotor. You can order direct from them in GB or RoversNorth has them as well.
Had 3 LR OEM rotors that left me stranded.