'91 Comanche 4.0

[jeepster1991]

I have a '91 Comanche 4.0 I just replaced the dummy lights with real gauges. Not realizing that the Sensor on the thermostat housing does more than just monitor the temperature of the coolant. What I need to know... is there any way to fool or bypass the computer into thinking that original sensor is still there. When starting the truck it stalls or almost stalls for about 30 seconds and runs really rough for a minute or 2 after that. If i reconnect the original sensor it starts fine, but then the auxillary fan doesn't kick on when needed and the truck runs way too hot. The reason i replaced the dummy lights is because the water pump went out and the motor got really hot before any warning light came on. I would really appreciate any input or thought anyone may have on this matter.

 

[carnuck]

Hook up a bypass switch to turn the fan on manually and leave the sensor attached.

 

[xjmarc]

Find another spot for the thermostat sensor.

 

[superj]

doesn't the early 90 and 80s models 4.0 have another threaded boss on the head for an extra temp sensor, on the back side?

 

[Bounty__Hunter]

If memory serves, there's two temp sending units, one for the gauge and one for the 'puter. You need to replace the one for the gauge with one from a jeep with the full gauge cluster, and leave the other sending unit along. I believe one is toward the front of the head and the other is near the rear.