I have a 1991 jeep yj - when I turn the key everything powers up as it is suppose to - but the engine does not crank ( I do not hear the strater clicking or anything) I thought it might be the ignition key cylinder since sometimes it would crank and start if I would play with the key - after replacing the key cylinder it worked fine for almost a week and now its doing the same thing - what do you think the ignition switch or ????

Maybe wired up the ignition wrong way round.if not then check the relay, then check solenoid on starter.

With a test light follow the wires from the battery to the fuse box to see where you lost the connection. You may have a burnt fusable link. . Run 12 v directly the the fuse box and see if that helps.

Ok, so the engine turns (cranks) when you turn the key to start?
Or, the engine turns slowly? Or, the relay clicks but the engine does not turn? I'm trying to help and you aren't giving me anything to work with!!! Tell me EXACTLY what is going on there...I can't see or hear it...you can.

see if your engine has a ECT sensor (temp sensor that delivers information to your ECM) they are installed on the intake side of the cylinder head, it usually has 2 cables, have it checked replace if necesary

the fuel sending unit is probably stuck and need to replacing. common problems to many older vehicle it tend to read sometime correctly and sometime not at all. the sending unit will be in your gas tank.

check fuel pump relay, check main fuses

i have a 1988 jeep wrangler 6cyl with 5 speed transmission. I was shifting the jeep and it got stuck in third gear. We opened it up and saw that the linkage is aligned and everything is in place. I dont know what is wrong and what to do next. please help ....

Did you replace the coil because it wouldn't start before? If it ran before, there must be a mis-connection somewhere. I assume by your stating that 'it turns but will not crank', to mean that the engine will crank over with the starter but won't start and run. True?

when you turn the key to crank the engine can you hear a click each time you turn the key. If you can hear it that is your starter solenoid. It is suppose to connect the battery to the starter motor. speak pf coincidence I had that exact same problem with my 94 F150 today. On the way home I stopped and bought a new starter, (which by the way comes with a new solenoid already attached to the starter motor). If you can hear the click I'd say your starter is bad. If there is no click, Your solenoid is not working. The problem could be no voltage is getting to the solenoid, or the solenoid is bad. No voltage getting to the solenoid can be checked by putting a voltmeter on the smaller wire going to the solenoid and turning the key. You can make a substitute voltmeter by buying a 12 volt car light and a socket to match connect 2 wires to the socket and you have a voltage indicator, put one wire on the smaller wire on the solenoid and the other wire to the engine metal (the ground wire). turn the key and see if the light come on. If it doesn't the solenoid/starter is bad.

Hope this helps