Second opinion] Why won't my Jeep start?

Hi and welcome to Just Answer! My name is \*\*\*\*\* \*\*\*\*\* I will be the expert to assist you today. I’m sorry you’re having trouble with your vehicle; I know how frustrating it can be. Please understand I do not know your level of automotive expertise so I may need to ask questions to find out information in order to provide the best possible service and solution. There are times when it may take me a moment to respond because I may have to look up information about your concern. I appreciate your patience. You mention the Jeep won't start but in order to assist will need more information. What year is the Jeep? which Engine? Does it Crank Over and just not Start? or does it not Crank over? Are there any Warning Lights illuminated on the dash?

It looks like you may have gotten busy so I will answer based on the information provided. There are three things that make an Internal Combustion Engine run and that is 1) Compression, 2) Spark, & 3) Fuel. For those systems to operate there are Electronic Control Units on newer vehicle's to control everything from Idle Speed and Timing to Starting and Charging. Older vehicle's use mechanical systems to control fuel and spark. (Distributor and Carburetor, Ignition Switch) If the vehicle cranks over but won't start you'll need to determine if it is a lack of Spark or a lack of Fuel or due to an internal Engine issue affecting Compression. If the engine does not crank over then it can be an Electrical issue (Battery, Starter, ECU, BCM or the Keyless Control system) or a mechanical issue (Internal engine damage, damage to the Ring Gear, Starter failure or Battery Cable issues. The vehicle also needs to have a good Ground circuit no matter the year. If you can provide some more information I would be glad to offer further assistance to determine the root cause of the Jeep no start. Best of luck with this and please be sure to update me with the results. Have a safe and prosperous new year!

2006 Jeep cherokee limited 4.7. 4x4. It cranks over but no start no jump start. No quick spray start. New Alternator new starter new batttery

Hi, thank you for that information. Failure for the vehicle to start with a Fuel Starter type spray would indicate an issue with Spark or Spark Control. Are there any warning lights illuminated on the dash? if so, do you have access to a Jeep compatible Scan Tool?

Because it cranks over you now need to determine if it is a mechanical issue with the engine that is preventing starting or an electronic issue with control. If electronic it will require the Scan Tool for proper diagnosis and repair. If it is a mechanical issue diagnosis may be performed with hand tools (Compression gauge) Please let me know if you're able to scan for codes? Thanks.