Will not start.Can hear fuel pump when I start with key.But, will not run. It does crank.Check engine light is also on.Sensor maybe?

Put key in IGN and turn to run. All warning lights should come on, including the check engine light. Then turn the key to crank. As the engine cranks and the crankshaft position sensor detects rotation and reports it to the PCM, the check engine light should go out. If it stays on, the PCM isn't getting input from the crankshaft postion sensor. Check the connection or replace the sensor.

No. it wouldn't keep it from starting. If the engine cranks but won't start, probably gas or spark (ignition) related. Do you hear the fuel pump in the tank turn on for a couple of seconds, when turning key to on, not start? If you cannot hear the pump, better check if you are getting gas up to the engine. Maybe the fuel pump quit, or the pump circuit needs looked at. The pump should briefly turn on with key on to pressurize the fuel system-the fuel line and the fuel rail where the injectors are. Then the pump will turn off, and only come back on again when the engine is cranking, and stay on when running.
Correct fuel pressure is important for easy starting, and good engine performance. Have the fuel pressure checked against the specification for your vehicle. If fuel pressure is good, check the ignition system-check for spark.

check to see if the cam shaft is turning while cranking the engine (broken timing belt) run fault codes to find faulty sensors.

And what does it do now? Does it crank over and not start, or just no power anywhere? If nothing, no power, recheck your battery connections, grounds, for something jarring loose, maybe a relay in the power distribution center (by your battery) jumped out of its socket. Gotta check around...But if it cranks over, but won't start, you need to review the basics for this condition: needs fuel and spark to run. Are you getting fuel up to the engine? Can you hear the fuel pump buzz on for 2 seconds when you turn key on? That 2 seconds is to pressurize the fuel line. When you start cranking, your pump will come on again, and stay on when engine is running. You can only HEAR the pump when someone turns key to on, and you stand or squat near the tank to listen for it, maybe with tank fill cap removed. If you cant hear the pump your FP relay would be the next place to look for a problem of no power to pump. If pump IS working, then back to engine: check if ignition (spark ) is working. Easiest way: pull spark plug wire, remove plug and put it on the wire you pulled off. Ground the threads of plug on metal of engine, have someone crank it, and watch for spark at that plug. If no spark, check another wire with same plug. No spark means you need to diagnose your ignition starting circuit. Among other things, this involves checking for power to coils, power to the computer (your check engine light DOES come on when key on, right?), a lot of things that a diagnostic flow-chart covers to pinpoint the problem. A good repair manual could walk you through it, if you have a multimeter. If not, you may need someone to help you. If you DO have both spark and fuel up to engine, it's simplified some, but still problematic. Crank position sensor? injector circuit? Good luck, M>, and don't give up.

Probably the crank sensor, do you hear the fuel pump 'buzz' when you turn on the key (not cranking the engine, just key on)? If you do hear the fuel pump (only lasts about 2 seconds), it may be the ignition module, otherwise it is probably the crank sensor.

Thanks for choosing FixYa Brian and welcome. If your car is cranking, you need to check for fuel and spark. Make sure your fuel pump is kicking on. You should be able to hear it when you first turn the key. It makes a buzz sound for a second or two. If it is not, check the fuel pump fuse/relay, and reset button, if you have one. If you hear it, check your fuel filter. It may be clogged. Check your fuel injectors also. You can check your fuel pressure and this way, you don't have to check all of them. If the pressure is correct, start checking the ignition system. It could be your spark plugs, coils, wires, coil packs, distributor, dist.cap, rotor. Check your timing belt. It may be a bad cam sensor or crank sensor. It can even be your computer. Your best bet is trying to scan it for codes. This way you know what to look for. If your check engine light is on, you should be able to get the code. I know it is a lot to check but anyone of them can be the problem. Test for spark and test for fuel pressure. If you have both, it eliminates most the parts above. That is the two test you need to run first so you don't have to check each one. If it is not cranking, check your battery first. Make sure it is good and has a good connection. Check your ignition fuse. Check your starter and starter solenoid. Hope this helps.

you need to sort out if fuel or spaark issue. Can you hear fuel pump in gas tank run for 5 seconds when you turn the key to ON? Spray a burst of starting fluid into the throttle body or bgi air intake hose and see if it starts for a few seconds. If yes, then you have a fuel issue, maybe need a pump. Need to drop the tank to do that though. Check for 40 psi of pressure first.

If not, then it could be no spark. bad crank sensor, cam sensor, etc.

Is the yellow check engine light on too? If yes, get codes to find cause.

well if it is cranking its not starter or battery . maybe check to see if fuel pump is working .check fuses. you should be able to hear pump run for a few second . if pump working maybe fuel filter or sensor like throttle position ,air idle sensor. make sure all wires are hooked up on alternator & starter . no vacuum hoses off any where . is check engine light on ?

Alarms usually won't allow the engine to crank. If it is the alarm, arming then disarming it usually gets them to start. However, you probably aren't that lucky. Probably the most common problem for Cherokees with ignition issues is a crank sensor or a fuel pump. Listen to hear if the fuel pump runs when you turn the key to the run position (it will only run for 2 seconds, so have someone else turn the key while you listen at the gas filler neck)

Hello Johnholley
I am wondering do you hear the fuel pump when you just turn the key into the on run position not crank just in run and listen and see if you hear the fuel pump run for a second, If you don't hear it you will want to check for power at the fuel tank, and have some one cycle the key while your under the truck with a test light. Hopefully you have power and you hear the fuel pump run. Now if you do hear the fuel pump running then the next thing you will want to check is for spark, It could be the ignition module or pickup coil. check out those thing and I am sure you will be able to figure out whats going on. If you don't get back to me and we can try a few other methods. I sure hope that helps you out johnholley. and thanks for using Fix Ya Bear001