Extremely cold natured YJ

[Cwburrell]

I have an 89 wrangler YJ TBI with 2.5 liter 4 cylinder that is hard to start when it’s cold. It will fire rather quickly but immediately dies. Sometimes it takes 15 or 20 tries to keep it running. Once it warms up, it runs well. I noticed the electric fuel pump stays running almost constantly when the key is turned to the run position. Should it only run for a few seconds until it pressures up and then kick off? Any suggestions would be appreciated.

[Ecomike]

Being a 2.5 L TBI, that was part GM stuff and part Chrysler stuff, I would track down some folks familiar with it. I thought at one time they MPI, but they may well have some differences I know noting about. Nick at nickintime on youtube, or here, may know a little about them, as his new REM scanners can now access the 2.5 L, 4 banger ECUs as well as the 4.0.

Maybe the main difference is just one injector??? If so, I could help some.

Oh, and it also sounds like the FPR is bad reading the first post here (or relay is stuck??). Unless the TBI had a lower pressure, and different pump and FPR from the 4.0s ??? I worked on an 84 once and it had an old style mechanical pump that ran off CAM.

[Ecomike]

Since it is temp related I would check the MAP Vacuum line and ends for any weakness/leaking at all.

Check the IAT air temp sensor in the Intake and clean it. Test it for proper resistance at cold temps.

Check the TPS voltage when cold and warmed up. And for sure clean up the sensor ground contacts surfaces!!!

[Cwburrell]

MAP I’m assuming is manifold air pressure? I’ve checked all vacuum lines but I’ll go over everything again just to be sure.

I replaced both the IAT and TPS early on in the troubleshooting but it didn’t change anything.