06cumminsman

Got an 88 that was swapped to a 94 4.0 ho from renix. Had an electrical issue somewhere that melted the wire from the ignition coil (think that’s what it is behind battery) back to an unknown location while out riding. Straight wired the fuel pump to toggle switch. Jeep has no gauge cluster since it barely worked and I added essential aftermarket gauges. All has been fine until a few weeks ago I ran out of gas. Put some in and it had a rough idle with no throttle response. Cleared up and I drove to the house about 5 miles. Went to fill up tank and if I start with clutch in or stop and don’t hold slight pressure on throttle it will rough idle and takes a while if patting the gas to catch up and run smooth. Normally if I start without clutch it will be fine and only have the rough idle when starting with the clutch. Now it will randomly start doing the rough idle while sitting. Seems to be more prominent when temp is around 180-190 or when I push clutch without holding pressure on accelerator. Fuel pump is 4 months old, plugs, wires, dis cap, rotor button, cos 6 months old, swapped iac, tps, maf sensor and cleaned tb with no change. Changed fuel filter today and no difference. I’ve sprayed starting fluid and wd40 on Vaccum lines with no change. Next step is check fuel pressure but I don’t see that since when it’s running it will do great until it does the rough idle but after it allows throttle response it runs normal again. Any idea what else it could because I’m completely stumped right now. I know changed parts are good except cps cause I swapped them from my other xj and it has no issues before or after.

cruiser54

Which fuel injection system is on the engine?

06cumminsman

What you mean? Sorry thought all 4.0 had the same system. Injectors mounted off rail and tb beside them on intake. When I swapped from remix I kept the intake from that engine and mounted to the ho block cause the tb was different and the accelerator wouldn’t attach. Can’t remember what was different off the top of my head

cruiser54

Just answered on Jeep Forum.

I know you guys love to post the same thing across multiple forums thinkin you'll hit the jackpot with the exact answer you need somehow.

But, for those of us trying to help and respond, this is a HUGE PAIN IN THE ***!!!