Ok, got XJ this summer. As it has gotten colder the cold starts have gotten worse. I put a momentary contact switch in to feed power tot he ballast resistor that feeds the fule pump power. So, I push it and it runs the pump. Tried this as a way to "prime" the system. It does not seem to help. I got a fuel pressure gauge at Harbor Freight. I have good pressure but it drops to around 10PSI afterr I shut it off. (Thus thinking the switch would let me get things primed back up). I hhave to crank for like a minute and it will finally catch and e very cold blooded. If i dare give it too much gas it will die like it is running way too lean. I did try hitting it with starting fluid when it sat all day and would not start and it fires it right up. So, my issues is fuel, I can prime the system but it does not seem to help. I am wondering if the ECM is not enriching the mixture when cold. Can anyone explain how the system knows to enrich the fuel mixture? Also, I replaced the IAC unit and the Intake air temp sensor and this did no good to help cold start.

 

Have you changed the fuel pump? If the pressure drops that much after you shut it off, the pump is not holding like it should.

 

so this morning I went to start it with the temp sensor unplugged. Way better start. So, I feel my issue is the ECU is not setting a rich enough fuel setting. I did put the diff. 703 Neon injectors in this summer. Any reason those could put the ECU in a position that the ECU cant supply a rich enough mixture for cold weather starting?

 

on the few cold days we have in fl mine would do the same thing i replaced the map sensor stoped instantly

 

Fixed! It was the temp sensor that goes in the thermostat housing in front of engine. I had picked up a non running Cherokee and tried sensors 1 at a time, then took the truck to the U-Pull It. Got a set of 4 aluminum wheels and tires and a few other parts and got $50 more for the thing than I spent!