1990 4-Cylinder Comanche Lurches, Loses Power At Low Speeds

[eric.toupin]

Hi All,

 

I have a 1990 Jeep Comanche, 2WD 2.5L 4-Cylinder. Manual AX5 transmission. I've done some minor transmission / clutch work on it with plenty of help and support from the forum. Generally, it runs fine (now). But...

 

Recently it's been doing two strange things:

1. Losing power (shutting off) at low speeds, normally when jarred or bumped. It starts right back up when this happens. Most often, this can be seen when it's parked and I start it, then release the parking brake. When the parking brake jolts, the truck loses power. I have to re-start it. Also, on occasion, it loses power at low speeds (parking lots, mostly) often on bumpy terrain. It always starts right back up, but for the moment when the power steering fails, it's no fun.
2. Lurching / losing speed while driving. When driving anywhere from around 30 to 55, it sometimes suddenly slows down a little -- just a mile an hour or two -- but very quickly, sort of lurching a bit. I can normally compensate by pressing the gas pedal down further, then it just sort of evens out. It never gains speed while lurching, only loses speed. And most often right around 40 - 45 mph. It feels like it's either losing power or gas suddenly -- but the truck doesn't shut off of anything.

I recently (several weeks ago) lost power completely (truck wouldn't start) and found out that the main battery cable was corroded and much of the insulation had rotted off many of the cables. I got the truck running again with some electrical tape and a new clamp for one of the battery terminals. I imagine the above problems are related to electrical issues, but don't know how to troubleshoot them. The battery cable itself is very complex -- lots of wiring in there going who knows where.

 

I also on occasion have some odd electrical issues -- namely the windshield wipers behaving unexpectedly and the turn signals staying on until fiddled with.

 

Anyone have electrical experience on this or a similar truck? Do these all sound like electrical issues?

 

I'd love any advice, tips, feedback or whatever.

 

Thanks much, this forum has always been a huge help.

[onlyinajeep726]

Bad connection to the fuel pump?  There's a 6-prong black plug that powers the fuel pump and tail lights under the driver side kick panel (right where the parking brake slides up and down).  Verify that is firmly plugged in and that the connections are not corroded.  Looks like the one below (mine's labeled "MJ" upside down in my truck).