Crank postions sensor
11-29-2009, 05:19 PM
#1
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Year: 1991
Model: Cherokee
Engine: 4.0 H.O.
Crank postions sensor
recently here in michigan it has begun to get cold, now i am having issues with initial start up, it cranks and cranks and cranks then fires up and it just started doing this. but it runs fine once it does, if i shut it off and start it right back up it starts fine, but if i let it sit for awhile then it takes a second to fire up again. now i think my crank position sensor is the problem, can they be tested (ohms, volts, etc...) if so how many ohms or volts? and how much psi does the fuel rail have?
1991 jeep cherokee laredo 4.0l HO auto 4x4.
what do you guys think, am i on the right track, fuel filter was just replaced.
1991 jeep cherokee laredo 4.0l HO auto 4x4.
what do you guys think, am i on the right track, fuel filter was just replaced.
11-29-2009, 05:26 PM
#2
CF Veteran
Maybe there is some condensation in your tank?
Maybe the fuel is condensing during the night, or losing pressure in the fuel lines. Causing the fuel pump to have to build up pressure again. Think about it, when the engine is running the fuel is hot/warm so it expands. Then it gets cold at night and the fuel contracts, probably losing pressure..
Next time you go to start it in the morning turn the key on until you hear the fuel pump shut off, DO NOT START THE ENGINE. Turn the key off, then back on and let the fuel pump run again. See if this helps.
Where are you from in Michigan?
Maybe the fuel is condensing during the night, or losing pressure in the fuel lines. Causing the fuel pump to have to build up pressure again. Think about it, when the engine is running the fuel is hot/warm so it expands. Then it gets cold at night and the fuel contracts, probably losing pressure..
Next time you go to start it in the morning turn the key on until you hear the fuel pump shut off, DO NOT START THE ENGINE. Turn the key off, then back on and let the fuel pump run again. See if this helps.
Where are you from in Michigan?
11-29-2009, 06:30 PM
#5
CF Veteran
It could be the cps, but those usually fail in heat. You dont really hear about them failing because of teh cold very much.
Whens the last time its had a tuneup?
Whens the last time its had a tuneup?
11-29-2009, 06:33 PM
#6
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Year: 1989
Model: Cherokee
Engine: 4.0 liter
how many miles does it have on the motor? i have had frequent encounters with bad cps's on multiple fuel injected jeep motors not just 4.o liters... i would replace it and see..there normally not to spendy to fix and its just 2 bolts
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11-29-2009, 10:14 PM
#8
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Year: 1989
Model: Cherokee
Engine: 4.0 liter
11-30-2009, 04:10 AM
#9
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Year: 1991
Model: Cherokee
Engine: 4.0 H.O.
it has 124,000 on it and i got it for free. the cap, wires and coil all look good but im going to replace them today and see what that does for me. if that doesnt help, then the cps, after that fuel pressure test
11-30-2009, 07:14 AM
#11
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Year: 91 with lots of 01' parts
Model: Cherokee
Engine: 01' 4.0L
i agree with frankz...you might be losing fuel pressure over night and the fuel pump is trying to push dense, cold gas back thru the lines causing the long crank time.
12-01-2009, 06:44 PM
#14
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Year: 1991
Model: Cherokee
Engine: 4.0 H.O.
i performed the fuel pressure check and i have 20psi with the key in the on postion and dropping fast, when its running i have a solid 31psi?? does this make sense at all?
12-01-2009, 07:48 PM
#15
Yes it does.
Do the pressure test again and as asoon as the pressure max's out (Key On, engine Off) Clamp off the rubber fuel line with a pair of needle nose vise grips. If the pressure drops then you've got a bad injector(s), if it stays steady you've got a bad checkvalve in your pump assembly.
Do the pressure test again and as asoon as the pressure max's out (Key On, engine Off) Clamp off the rubber fuel line with a pair of needle nose vise grips. If the pressure drops then you've got a bad injector(s), if it stays steady you've got a bad checkvalve in your pump assembly.