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87 xj cranks but wont start

xjcollecter

NAXJA Forum User
Location
livermore CO
OK i have an 87 xj two door with the 4.0 and a 5 speed. one day driving to work my throw out bearing went out. so when i got it home i replaced the bearing and went to pull it out of the garage but it just cranked. so i did some tests. Fuel presser is at 42 psi, but no spark or injector pulse. so i put a new cps in, and it fired up...... and then died. Started it again rpms went to around 2500 and it then died. After that it would only crank and still no spark or injector pulse. So another cps and it fired up once and ran and drove great. next morning no go, just cranking over. So with that said ive put a new icu,coil,adjusted the tps, and even tried a new ecu from my other 87. but ive gotten nothing. Anything helps.
Thanks
 
ok, ill try cleaning it in the morning and let you know what happens

Just reinstall the CPS and move it closer to the Flex plate by making the mounting hole larger. I also found, at least on mine, that super thin washer between the bell housing and the CPS arm, doubled my cranking AC voltage.

My battery barely works right now, old like me, LOL, this month and she still fires right up after sitting for week. Also stock CPS mounting you need solid battery power at the starter to get peak cranking rpms to get enough CPS voltage for the ECU to see.
 
Just reinstall the CPS and move it closer to the Flex plate by making the mounting hole larger. I also found, at least on mine, that super thin washer between the bell housing and the CPS arm, doubled my cranking AC voltage.

My battery barely works right now, old like me, LOL, this month and she still fires right up after sitting for week. Also stock CPS mounting you need solid battery power at the starter to get peak cranking rpms to get enough CPS voltage for the ECU to see.

C101 can be a huge factor in this and other running issues. Never a bad idea to clean it.

Also, unplugging the CPS and plugging it back in, and if it starts, indicates that connector needs attention.
 
finally got some time to mess with the jeep again and i cleaned the c101 and it still wouldn't fire but decided to replace the cps with another one i had and it fired up and runs great again, thanks for the input.
 
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