97 tj no spark...

mtmech

Member
Joined
Oct 25, 2010
Location
camp lejeune nc
Ok here goes... Went mudding the other day... An died in the hole.. It didn't die right away kinda sputtered like my coil or distributor got wet. Got it hole and let it sit over night... Tried to start but no spark. Changed the coil and still no spark. Next in the list will be my distributor but I'm also finding that it could be the crank sensor... Thoughts? Anyone have this happen? Any help will be appreciated. Thanks
 
Jut changed the crank sensor on the bell housing... Still nothing... Going to do the distributor now... If this don't work... I'll be looking for a ecu for an older jeep...
 
if it was the crank sensor then you would have no fuel or spark, and the guages on the dash would be flatlined with the ignition in the ON position(fuel level,battery, etc). take the distributor cap off and rotor and clean it all thoroughly. it may be the cam sensor under the distributor cap. you may have burned up your ignition control module. double check to make sure you havent stripped the gear onthe distributor. with the cap off have someone crank the motor and make sure the ign. rotor spins. check at the rail for initial fuel pressure. pull out all the spark plugs to check for debris or water. spin the motor over with the plugs out to press out anything that might be in the cylinders. you cant confirm anything has gone bad unless you have the part cleaned and relubricated or back in to specifications.(had to do this stuff a couple times with my yj
 
and thats why i didnt have spark...
 

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gt500swim said:
if it was the crank sensor then you would have no fuel or spark, and the guages on the dash would be flatlined with the ignition in the ON position(fuel level,battery, etc). take the distributor cap off and rotor and clean it all thoroughly. it may be the cam sensor under the distributor cap. you may have burned up your ignition control module. double check to make sure you havent stripped the gear onthe distributor. with the cap off have someone crank the motor and make sure the ign. rotor spins. check at the rail for initial fuel pressure. pull out all the spark plugs to check for debris or water. spin the motor over with the plugs out to press out anything that might be in the cylinders. you cant confirm anything has gone bad unless you have the part cleaned and relubricated or back in to specifications.(had to do this stuff a couple times with my yj
Click to expand...

Sorry, but there is lots of incorrect info in this post. If a crank sensor fails, signal wise, you will still have fuel pressure and injector pulse, but no spark. The PCM uses the crank sensor signal solely for a signal to fire the coil (laymans terms). A TJ (or any late model Jeep) does not have an ignition control module. All ignition control is via the PCM. The only time all of the gauges will be flatlined is in the event of a bus failure. A shorted crank sensor *can* cause that, but its not an automatic thing.
Just clarifying for future reference.

To the OP-Glad you found the issue. Should be an easy fix at this point.
 
Should be an easy fix... Motor has less than 1300 miles on her and still under warranty... And not to mention that's the first time I took her off road since I put the motor in... Suppose that's what happens with 275 ftlbs on stock 4.0 parts...
 
Jody Treadway said:
The only time all of the gauges will be flatlined is in the event of a bus failure. A shorted crank sensor *can* cuase that, but its not an automatic thing.
Click to expand...

Yep I agree when my ECM failed on the TJ, the Symptoms were flat lined Gauges and no spark. New ECM, she fired right up. Good info Jody.

@ OP - Glad you found the issue
 
Found another problem with the block.. When the chain snapped it smackevthe block and put a hole going to the push rods... So of course I'll be rebuilding this... Got a block comin to me later today. I should be able to reuse major componets. But will be swapping when needed... I may just go 30 over an make it a 4.7... Currently it's at. 4.5... All that would need to change would be the bore... Decisions decisions lol..
 
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