Why is my car with half tank of fuel only craking but not starting

This kind of problem isn't something we can just point to and say "That's why"; it requires troubleshooting to figure out what's going on with your Range Rover.

Engines require three things to run; air, fuel and spark. Modern engines add in the complexity of the computer system that runs the engine and all the associated sensors it uses, so you have to start narrowing down the reason first.

You might start out by asking the computer if it's seeing a problem. That requires a scan tool hooked up to the OBD-II port and obtaining any Diagnostic Trouble Codes (DTCs) that might be present. If there are any, they may point to where to begin your troubleshooting, but if the vehicle isn't starting there may not be any codes present.

Off the top of my head, here are some questions I'd try to answer to get you going.

• Do you hear the fuel pump start up when you get in and/or turn on the key?
• Does the engine have spark? You might have to pull out a spark plug, plug it back in and hold it against the engine block while cranking the engine to see if it's sparking.
• Is the engine getting fuel? Check the spark plug to see if it's wet with fuel, or pull out an injector if possible and see if it sprays when cranking (put it in a jar so it doesn't spray everywhere when you do).

More sophisticated tests are available, such as verifying the fuel pressure with a gauge, or a scan tool can see the airflow and spark timing as it's cranking, but those are tools that cost thousands of dollars, usually found in a mechanic's shop.