Loss of power when off-road

[ajoyce09]

I have a 1988 YJ 4cylinder 5 speed. I can drive on paved roads without issue for over an hour, but when I take the jeep off-road and get bouncing around staying mostly in first and second gear, in about 15-20 minutes it starts losing power, bogging down and will eventually die altogether—almost like it’s in limp mode. On paved roads it will do the same thing but it takes much longer—can usually run for about an hour before bogging down.

If I let it sit for about 45 minutes everything goes back to normal for a while.

My initial thought was a restriction in the exhaust, maybe a plugged cat, but I have not cut it out yet. I have done a new fuel filter, plugs and oxygen sensor so far.

Any help would be greatly appreciated

 

[JKP]

Probably either a weak fuel pump heating up, or a coil going out when it gets hot.

On mine, the coil would get weaker the longer I drove it. Eventually if you floored it, or loaded it down, it would just cut off like a switch.

The fuel pump felt more like hitting a rev limiter, ran rough and wouldn't go any faster, but never shut off.

 

[Gilaguy23]

I cant recall if your year is carbed. If that's the case Its quite likely your drowning the engine with fuel when bouncing around. Those carbs aren't known for reliability or good manners. One cure Ive seen on Holley's when off roading is to add a section of tubing to the bowl vent. This keeps fuel from splashing into the intake and keeps it in the bowl. A better option is a FI kit.