88 Comanche won't start when warm

[driggity]

Recently my Comanche hasn't wanted to start back up after a short drive (I haven't driven it very far since this started happening). When I try to start it it back up the warning lights on the dash go out but nothing happens. No noise at all. I'm assuming the starter is bad but is there some other problem it could be? I did change the sensor in the radiator that controls the aux cooling fan and had the refill the anti-freeze but I don't know if that could have anything to do with it. It seems to run fine and no warning lights are coming on.

 

Thanks.

[Garvin]

I had the same thing happen to my '90 Cherokee, it ended up being the crank sensor. This is a fairly common issue with them.

 

The info below comes from http://www.lunghd.com/Tech_Articles/Eng ... ostics.htm , really close to the end of the page.

 

Check the connector first

If you've just stalled out with same symptoms... unplug the CPS & plug it back in. If your motor fires back up you might get off easy, but don't count on it lasting forever. I dunno what doing this accomplishes other than cleaning the connector contacts enough to let additional voltage through to the computer. If unplugging & replugging worked then unplug the connector again and clean those contacts off. Then apply some OX-GARD, or other electrical contact cleaner & protectant (dielectric grease).

 

There is a distinct possibility that you're not getting a signal due to a faulty connector itself as well. Some people have cured their CPS problems by simply cutting the connector out of the harness and SOLDERING the wires together (Use heat shrink or electrical tape around the wire, of course!) Other's have replaced the connector with a newer, waterproof version from an electrical or automotive supply store.

 

Test#1 - Get a volt/ohm meter and set it to read 0 - 500 ohms. Unplug the cps and measure across the CPS connector's A & B leads. Your meter should show a CPS resistance of between 125 - 275 ohms. If it's out of that range by much; replace it. (* - Note: HO engines are measured from the B & C connectors and should have near zero ohms.)

 

Test#2 - You'll need a friend to help ya with this one.

Set your volt/ohm meter to read 0 - 5 AC volts or the closest AC Volts scale your meter has to this range. Measure across the CPS leads for voltage generated as your friend cranks the engine. (The engine can't fire up without the CPS connected but watch for moving parts just the same!) The meter should show .5 - .8 VAC when cranking. (That's between 1/2 and 1 volt AC.) If it's below .5vac, replace it.

 

[88SporTruck]

My 88 2.5L would not start when I got it. Turns out the CPS connector was all full of crap inside. Used some CRC electrical cleaner and a wire brush on it and it fired right up.

 

Check that connector.