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JEEP wont FIRE up. cranks fine

(1990 Jeep Cherokee)
in Ocala, FL on May 19, 2010
actually this is a 1988 Cherokee Pioneer. 2wd 4.0l 6-cylinder. no auto windows and no check engine light. I want to know what code reader to use or how to find one for this jeep. Also, I need to know what would prevent the thing from firing up. I replaced the rear main seal on the transmission. It was running rough and i found out the Fuel injectors were mis-firing causing fuel to enter the oil pan. After that happened it wouldnt start. I replaced almost all the sensors. heres the list: crank (speed)sensor, oil pump (rebuilt it dual gear type), entire harness for fuel injectors, new fuel pump, cleared out the fuel line, new fuel filter, new rotor and coil, new EGR and O2 sensors, even tried a different brain (computer), changed oil and new plugs and wires, cleaned out rockers and pushrods then re-lubed them. Still no start up. Fire is good at the plugs and the injectors fire fuel. any other ideas? I have done a few other things i cannot think of as i'm writing but need the answer to these 2 questions.
Thanks. emailis
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Popular Answer
on May 21, 2010
You may have damaged a few teeth on the flywheel, that the crank sensor needs to fire the motor, so it will not fire correctly anymore. This is not uncommon.
As for the scanner, I have seen the correct one at auto parts store. Your diagnostic is a dual connector that has a yellow cover, yes?
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on May 22, 2010
I replaced the rear main seal. teeth on the flywheel looked fine. the jeep ran before the gas entered the oil pan due to mis-firing of the fuel injectors. I dont know what else to check. I replaced the speed sensor and put a new timing chain on. I manually cranked the engine around three times and the timing marks lined up correctly. I still think this may be a sensor problem, but, not sure. i didnt change the TPS yet. Will try a new battery as a precaution. Any other ideas?
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