Water pump change messed up idle?

J-Dub253WA

New member
Hey guys I'm stumped? This afternoon I realized I was leaking coolant from my water pump in my 94 YJ (2.5 4cyl). So obv I went and picked up a new water pump and gasket. Prior fixes to this I did the thermostat and the radiator and have been working on cleaning the cooling system. So anyways pulled it apart. Installed new. Put it all back together just perfect and hooked back up the negative battery terminal. Filled my radiator with some coolant and water and started her up. Immediately idling high like in 2100-2500 rpms. I burped the system for a bit letting it take fluid and refilling. Not sure what I did that had anything to do with the idling te but I'm also not really a mechanic of any sort either. Any help or insight would be greatly appreciated. Anything I forgot ask!!


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mn jk jeeper

New member
the computer may need to be relearned
I would be sure the coolant is burped and full and try driving it around town at different speeds and stop and go
it should relearn its self after a bit
 

J-Dub253WA

New member
If the crankshaft pulley was moved in any direction during replacement of fan belt would this be the cause?


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billybob990

New member
Hey guys I'm stumped? This afternoon I realized I was leaking coolant from my water pump in my 94 YJ (2.5 4cyl). So obv I went and picked up a new water pump and gasket. Prior fixes to this I did the thermostat and the radiator and have been working on cleaning the cooling system. So anyways pulled it apart. Installed new. Put it all back together just perfect and hooked back up the negative battery terminal. Filled my radiator with some coolant and water and started her up. Immediately idling high like in 2100-2500 rpms. I burped the system for a bit letting it take fluid and refilling. Not sure what I did that had anything to do with the idling te but I'm also not really a mechanic of any sort either. Any help or insight would be greatly appreciated. Anything I forgot ask!!


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Check for vacuum lines, messing with the water pump would have no effect on the idle. You must of hit a vacuum line when doing it.
 

J-Dub253WA

New member
Seems as if everyone I call is saying the same thing I either hit a vacuum line or I have a nice nasty air pocket blocking the coolant temperature sensor in which is not able to relay back to the computer. I'm going to tilt the front up and continue to try and burp the SOB and if that don't work I guess I'll have someone look at it


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billybob990

New member
Seems as if everyone I call is saying the same thing I either hit a vacuum line or I have a nice nasty air pocket blocking the coolant temperature sensor in which is not able to relay back to the computer. I'm going to tilt the front up and continue to try and burp the SOB and if that don't work I guess I'll have someone look at it


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Just take a quick glance at the vacuum lines first there's not that many look around the fuel rail ( if its fuel injected ) I have a 2.5 in my tj and there is a line close to the pump on the fuel rail
 

J-Dub253WA

New member
Thanks guys ill check em and do some more diagnostics when I get home from work. Bob it is fuel injected I'm pretty sure we have the same motor to the T. I wonder if there is a detailed description of which exact lines are the vacuum lines? Any way to tell cuz ya of course we were u know up around behind the power steering pump which is right in front of the fuel rail and injectors and throttle body


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billybob990

New member
Thanks guys ill check em and do some more diagnostics when I get home from work. Bob it is fuel injected I'm pretty sure we have the same motor to the T. I wonder if there is a detailed description of which exact lines are the vacuum lines? Any way to tell cuz ya of course we were u know up around behind the power steering pump which is right in front of the fuel rail and injectors and throttle body


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there is a cluster of lines on the driver side of the throttle body there is 4-6 lines start there and trace them, if there all hooked up then start it and pull them off one by one and put your finger over them to see if there pulling vacuum and check for dry rot, when pulling them off be sure to pull them off where they end up, fuel rail, intake, brake booster etc. and not from the throttle body. good luck i hope you get it fixed.
 

J-Dub253WA

New member
So guys I'm still having issues! I have done a few vacuum tests including spraying carb cleaner on all the vacuum lines listening for a change in idle (dont worry ice cold motor) I've even taken off the throttle body and thoroughly cleaned the body, butterfly valve and the IAC valve. None of these things made any changes in idle. How could I know for sure if my IAC is bad before spending 90$ for a new one, also should I change the O2 sensor too? Could a bad O2 sensor make me idle high?


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