I have a 1992 Jeep Cherokee Laredo and when it is cold outside there is no fuel pressure and wont start. but when the day warms up there is fuel pressure and will start normally. I have changed the fuel pump but i am very confused as to what it could be. any suggestions?

 

Check all your connections for corosion or loose terminals.

 

Ever seen a check engine light? I'd scan for stored codes even if the answer is no. Takes 5 minutes. See procedure below.

For issues where there is a problem with either cold or hot starts, one engine management sensor that comes to mind is the coolant temperature sensor; the one that sends input signals to the computer.....not the one that sends signals to the dash gauge. Be sure to get the right one; I believe there are 2 on your vintage.

The coolant temperature sensor can be tested for resistance as it changes greatly over temp. Or they aren't too expensive to just replace it.
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OBD1 Models: 1991-1995
1) Start engine (if possible). Move transmission shift lever
through all positions, ending in Park. Turn A/C switch on and then off
(if equipped).
2) Turn engine off. Without starting engine again, turn
ignition on, off, on, off and on within 5 seconds. Record 2-digit
fault codes as displayed by flashing MIL.
3) For example, fault code 23 is displayed as flash, flash,
4-second pause, flash, flash, flash. After a slightly longer pause,
other codes stored are displayed in numerical order. When MIL begins
to flash fault codes, it cannot be stopped. Start over if count is
lost. Code 55 indicates end of fault code display.

 

I ran the check engine light. and it came back with a code 12. Correct me if im wrong but isnt that the code saying that the battery has been disconnected in the past 60 times the engine has been run?

And about the sensor...I have noticed that the gauge says the engine has been running about 20 degrees cooler. Would that be an indicator that it is that sensor or no?

 

No fuel pressure after sitting over night? Did you check the pressure at the rail with a gauge? A leaking injector(s) might be the cause of your loss of pressure.

 

So this morning i got up early so i could do some tests. and i had turned the key to the on position and after about 45 seconds i heard clicking from the relays and i touched them all to see which one was clicking and it was the starter relay. and after the clicking stopped i could hear the fuel come up the line. Im not sure what this means.

 

try a different relay