Author Topic: need help - jeep will crank but not start...  (Read 6469 times)

Red02TJ

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need help - jeep will crank but not start...
« on: November 05, 2012, 08:23:36 am »
my jeep is a 2002 wrangler with a 4.0 and 5-speed, has 100k miles.

so my jeep started off with a misfire-type knock. i finally decided to get into the engine's internals and found that a valve lifter was damaged, causing the pushrod to not work. this did not allow #6 cylinder intake valve to open, causing the noise.

i replaced all lifters, lapped the valves, and cleaned the head. checked the slack in the timing chain and verified tdc and timing marks were aligned. after putting things back, i went to start the jeep and it would just crank and not start. the jeep wasn't throwing any codes.

so i checked the fuel pressure and got about 45 psi. i ended up replacing the iac, camshaft position sensor, and crankshaft position sensor.

i tried starting the jeep again and it gave a low rumbled idle and died after 2-3 sec. after many attempts at starting, i got the same results. i even rotated the camshaft position sensor 180 degrees just to make sure the timing was okay. doing this didn't allow the jeep to idle at all, just crank. so i returned the sensor back to original.

i got a spark tester and tested each spark plug boot on the ignition coil rail. i got the same size and color spark for all 6. i checked the resistance of the fuel injectors and got about 10 ohms each. i pulled the spark plugs and smelled gas on them.

so i returned everything back and tried to start it once again. it cranked and cranked and had a low rumbled idle again, then died after 2-3 seconds.

i'm hoping it's not the pcm/ecu. i'm not sure if i provided all of my troubleshooting efforts, but i guess i'm too frustrated with the jeep. any help would be great. also, i was wondering if anyone has an ecu/pcm that i could borrow to see if my jeep would start, preferably for a 2000-2002 4.0 with a manual tranny.

thanks in advance for the assistance.
Larry Padre

pa2phx

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Re: need help - jeep will crank but not start...
« Reply #1 on: November 07, 2012, 02:42:09 am »
i am not in a position to help with the PCM but i was just thinking since you did all the head work that it might be worth checking the compression to make sure there are no issue there. good luck
John Michael

Red02TJ

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Re: need help - jeep will crank but not start...
« Reply #2 on: December 01, 2012, 10:46:29 pm »
an update:  compression was good on all 6 cylinders, spark test was good also. apparently i didn't soak the new lifters long enough, so not enough oil in them. i took the valve cover off and a few valves were not opening.

i took a syringe and squirted oil in the pushrod holes and slowly dripped the pushrods with oil. i then took a long flathead screwdriver and cut off the handle. i attached it to a drill and turned the oil pump. this allowed oil to fill the lifters and rods. i restored the cam sensor and synchronizer and the engine started right up!!!

now i have a stipped crankshaft pulley bolt. the never ending battle continues...
Larry Padre

MUDDY

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Re: need help - jeep will crank but not start...
« Reply #3 on: December 24, 2012, 08:14:42 am »
USE EZ OUT TO GET BOLT FREE
98 grand cherokee mild liFT
97 CHEVY 3IN LIFT

Red02TJ

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Re: need help - jeep will crank but not start...
« Reply #4 on: December 24, 2012, 06:46:40 pm »
thanks for the info. i did get the bolt out and tapped the threads to clean them up. the jeep is up and running. all that needs to be replaced is an o2 sensor.
Larry Padre