89 cherokee wont start

:banghead: I have an 89 cherokee....4.0.....with 200,000 on it.....was dying when letting off gas....and hard starting....then started losing power and finally had to tow me home....thought it was fire prob...replaced the plugs, wires, cap, rotor, and distributor...which the cam sensor is in dist. so new also...replaced the ignition module, ignition coil, and finally pcm.....the rotor didn't line up exactly at tdc...so replaced the timing chain and gears....it is the 14 teeth that it needs to be...and lines up perfect at tdc now.....then it started and ran till engine warmed up...then no power again....then ran thru fuel system....it had a leak down problem....but after pulling the pump and replacing the small hose in pump module it now has 35-40 lbs pressure when key is turned...also holds pressure good.......replaced the fuel filter, air filter, and pulled the fuel rail .....4 injectors of the 6 had bad spray, now after replacing the 4 injectors,,,they all mist good....at same time replaced several vacum hoses one at a time so none were mixed up....now it wont even start..... all happened in a couple of months ..because having to bench test most parts has taken a while ............. since i have owned it...the emissions light has been on. and the guy sold it to me said it was always on...took the egr valve off and cleaned carbon...wasnt too bad...but cleaned anyways...one last thing....I had a plug out checking spark and it started...twice....it will start with a plug out...but so not to burn valve or anything ..shut off. put plug in and then it wont start....wierd huh....last clue....it has weak spark...I think....it is yellow not blue...any help would be appreciated..........running out of ideas.......need blue spark.....only idea I have left is a cherokee bonfire....after all the money spent....would hate to do that...please help me save this jeep......need blue spark :banghead: :banghead: :banghead:

Check your ECU (computer) My friend had a problem like this in one of his cars. And it turned out to be the ECU.

Before you do anything with the ECU, check out the sticky listed at the top of this forum for troubleshooting. More than likely it is your CPS, or crankj position sensor.

Mike

also the emission light is controlled by a timer which turns on at a seperate mileage. You can replace the timer or do like most of us, whose cherokee has reached this mileage: either disconnect the timer or ignore the light.

Thanks wildman and kodking for the ecu suggestion...but I have already replaced that.....and also replaced the cps....however it was not slotted for any adjustment to get closer to flywheel.....tomorrow going to try to get a slotted one.....thanks for the emission light info....wasn't sure if it was automatic or if it came on because something had failed and was connected to the weak spark problem......it still wont start... not sure what u mean by the sticky at top of forum..this is my first post and have read a few threads but new to all this....please be patient and specific....thanks

Yellow spark at the coil is a sign of a bad coil....spark should be blue...
CPS is a real PITA on most all 89' XJ....it's located on the drivers side on the bellhousing at about the 11 o clock position....got a pic hang on lemmee post it up.....here tis....

http://img367.imageshack.us/img367/9080/pictures110xr3.gif

2 other options...

TPS...Throttle position sensor
ISM... Idle stepper motor

These 2 are located at the front of the throttle body...
Pic shows both.....
http://img230.imageshack.us/img230/5395/sensortpsdk2.jpg

one other part....
Map Sensor....

http://img355.imageshack.us/img355/6105/pictures042qf1.jpg