How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Edward Your Own Question
Edward, Service Technician
Category: Jeep
Satisfied Customers: 2988
Experience:  20 + years experience on various makes and models.
Type Your Jeep Question Here...
Edward is online now
A new question is answered every 9 seconds

I have a 200o jeep cherokee. It will crank but not start. I

Customer Question

I have a 200o jeep cherokee. It will crank but not start. I can get it to start using starting fluid and it runs fine. The only other thing is the alternator will not charge . have taken it off and it test fine. Looks like it not getting the necessary signal to engage the charging. They may be related but not sure.
JA: Have you checked the fuel supply? And are all the spark plugs working?
Customer: did you read my response. it starts and runs on starting fluid.
JA: What year is your Cherokee?
Customer: can you read
JA: Are you fixing your Cherokee yourself? What have you tried so far?
Customer: .
JA: Anything else you want the mechanic to know before I connect you?
Customer: ,
Submitted: 9 days ago.
Category: Jeep
Expert:  John Taylor replied 8 days ago.

Hello, My name is***** am a Chrysler Master Technician.

Sounds as if you may have a bad crankshaft position sensor. Is the check engine light on when it is running? Please be very careful using starting fluid in a gasoline engine, it can cause detonation and ruin your engine.

Customer: replied 7 days ago.
I replaced the crankshaft position sensor with a mopar part. I don't think it would run and start on starting fluid if was bad but I changed it out
Expert:  John Taylor replied 7 days ago.

We will have to do some tests to see what is causing it not to start on its own.

First test i would like you to try is to go into the fuse block under the hood, and look for the ASD Relay. Swap that one with the horn relay, and attempt to start the vehicle.

Customer: replied 7 days ago.
Changed out relay still no start
Expert:  John Taylor replied 7 days ago.

Ok, lets try looking at the fuel side. Swap the horn relay and the fuel pump relay, see if the vehicle will start. This is a odd issue, so bear with me, we have to check the simple stuff first.

If you swap that relay and it doesnt start, we need to check the fuel pump module. You should hear the fuel pump actuate when you turn the key to the on position. should sound like a "whir" coming from the back of the vehicle.

I understand it runs on starting fluid, but i am thinking maybe it is drawing fuel on its own after it gets started. Have you driven the vehicle after it was started with starting fluid?

Expert:  John Taylor replied 7 days ago.

Also make sure you have checked all fuses in the fuse block under the hood. You will need a test light to verify. If those are all good, we need to check and see if we have power at the fuel pump module connector. Key on, probe the connector with the test light and see if you have power.

Customer: replied 7 days ago.
I have not driven after starting since the alternator is not charging I will get the battery up on it tonight and try that tomorrow evening. Where is the module located on the fuel pump. I can hear it buzz with key on. I also have pressure in the rail. If I bleed it off it builds back up. One other odd thing if I unplug the ecu over night it will start one time on its own but never a second time
Expert:  John Taylor replied 7 days ago.
I am wondering if the skim (security) module has failed. It will not start if it has lost the secret key. If you can give me the last 8 of the vin, I can check in the morning for you.
Customer: replied 6 days ago.
Expert:  John Taylor replied 6 days ago.

Ok give me one min.

Expert:  John Taylor replied 6 days ago.

Be advised, you have a open recall on your vehicle.

Expert:  John Taylor replied 6 days ago.

The skim seems to be working because it will let you spin the starter over, and it will run without killing the engine after 2 seconds.

We need to check and make sure the pcm is getting the ignition feed signal

Expert:  John Taylor replied 6 days ago.

We need to check pin number 22 with a test light, see if it lights up with the key on.

Disconnect the black connector (c1) and check the pin in relation to the diagram.

Customer: replied 6 days ago.
Have 12.4 continuous with key to on position
Expert:  John Taylor replied 5 days ago.

Ok, that means the pcm is getting the proper feed it needs. This one is stumping me, lets try one more thing before I opt out and let another expert try to help you.

Since you are saying it starts and runs fine on starting fluid, it is getting fuel and spark. But seems something is messing with the staring injector pulse width maybe. The pcm will look at the MAP sensor as the primary input for the starting equation (speed density), it could be that the map is sending a scewed signal. Try disconnecting the map sensor and see if it will start in default.

Expert:  John Taylor replied 5 days ago.

here is the location of the map sensor on the throttle body

Customer: replied 5 days ago.
Still no luck on starting
Expert:  John Taylor replied 5 days ago.

Ok bud, i will opt out and see if someone else can help you. Have a good day!

Expert:  Edward replied 5 days ago.

Can you tell me if you have power to one of the wires at any fuel injector with key ON? thanks.

Customer: replied 5 days ago.
Ok here's what I have
Key on zero
First crank and start 12.2
Key off start retry 10.4If I wait for some period of time I can repeat
Expert:  Edward replied 5 days ago.

So when cranking does it hit at all and try to start? and no power to any fuel injector with key ON is a problem, but I'm wondering since you have power in START position if indeed it tries to fire up and run and then dies as soon as you turn the key back to the ON position.

Customer: replied 5 days ago.
After it set for some time it starts. Turn the vehicle of and retry and only the starter engages but does not try to start which is evident with low voltage to injectors but will start and run with starting fluid but alternator does not charge
Expert:  Edward replied 5 days ago.

Is this regular cherokee or grand cherokee? and does it have a 4.0 L straight 6 cylinder in it? thank you.

Customer: replied 4 days ago.
Regular Cherokee 4.0l
Expert:  Edward replied 4 days ago.

Here is the diagram of how the injectors get power, the ASD relay powers them up with key ON. The ECM (engine computer) grounds the ASD relay with the key on, Check all those fuses up top in this diagram, make sure they all have power to them and are good, and pull the ASD relay out and see if you have 2 pins in the ASD relay socket HOT with the key ON. the BLUE/YELLOW wire running to the ASD relay grounds the relay and it's ground comes from pin 3 and the ECM.