Funky Fresh

Does anyone know anything about the EVAP pump?

How can you tell if its bad?
What are some symptoms of a bad pump?
Would it cause low vacuum pressure?
Would it cause a rough idle?

ol"blue

The pump (if equipped) only runs on start up to pressurize the EVAP system to check for leaks. Normally it's the vacuum lines, charcoal canister, or solenoid that fail, not the pump. If yours did fail it should leave a code.
Unless there's a leak in the EVAP lines, which carry gas fumes/vapors, there shouldn't be a problem driving with an inoperative pump. Most Jeeps didn't come with them anyway. A leak in the lines can cause a rough idle.

chinoman

My check engine light came on and i got p1281(engine running cold too long) and p1494(incorrect input state detected for the leak detection pump pressure switch) so when i changed my oil i found a disconnected hose, (which looked un damaged) so hooked it back into the manifold. I followed it and it lead to this little deal that i think is my leak detection pump, and what i wonder is if its bad because it sometimes makes a clicking sound and its been about a week with about 100mile daily commute since i connected it back up and my chk engine light hasnt gone off, or maybe if i just need to some how reset my chk engn n how is it done? I also changed my thermostat because the engine temp dont hardly go past the quarter mark on my guage and made a little diff but it is winter time in MO.

ol"blue

That clicking noise is the purge solenoid on the drivers side inner fender, to the rear of the air filter housing. It's normal. You can use rubber on the mount to quiet it down some.
To reset/turnoff the CEL, disconnect the bat cables and hold them together away from the battery as far as possible for 20 seconds. That drains the residual charge in the PCM. Then after reconnecting the bat cables (you'll have to reset your clock and radio stations), drive it for about 20 miles but don't baby it. That way it can relearn the parameters of the engine.
If there's no further issues/faults, the CEL shouldn't come back on.
*The codes disappear after 50 key starts without removing the cables ( if the problems fixed and no further issues surface), but with the CEL being on it's in the "Limp home mode". You shouldn't drive very far like that. It's in an over-rich condition and will ruin the cat. converter.

The temp. issue can be caused by a thermostat that is of a lower temp rating than is called for which should be 195 degrees. Too low and it will think it's staying cold too long, causing it to run in an over-rich condition.
Let us know what you find.
And Welcome to CF.
Dan