Q: Car is running rich - 1990 Jeep Wrangler

asked by on November 04, 2016

Hoping to get some direction here. Im good with basic mechanical fixes but not a mechanic. More of a hobbyist.

Bought a 90 over the summer. Previous owner did a Howell TBI conversion and got rid of the carb. I knew it was running a little rich when I got it. Every once in a while it gives a problem starting (about 1once every 100 starts). The easiest way it seems to get it started is to remove the air filter. Im not too worried about that but figured I would add that for context. Also the floor seems to get hot when driving for a while.

Now that its gotten cold out I have the following happening:

Starts fine. Runs very rough until warm Has no power almost at all until warm

Any idea on what may be causing this would be really appreciated. If more information is needed let me know and I'll be happy to provide it.

My car has 120000 miles.
My car has an automatic transmission.

Starting any engine in cold weather is never an easy task as they simply do not like cold weather and do not run well in it. When you first go to start your Jeep on a cold morning and turn the key, there is a coolant temperature sensor which reads the temperature of the coolant relaying this information back to the computer.

The computer then makes an adjustment to the fueling of the motor to enrich the fuel mixture needed. This happens when the air is cool due to the density of the air requiring more fuel to maintain the same amount of power.

To avoid any unnecessary repairs, I would highly recommend having an expert from YourMechanic come to your location to diagnose and service your cold start injection system firsthand.

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