Diagnosing a cranking engine that refuses to start may involve troubleshooting more than one system on your Ford Explorer. However, it is a good idea to start with the easier and more common causes such as an empty fuel tank and low battery charge. And use common sense. For example, if your Explorer was serviced recently, then the associated components are a good place to start.
Step 1
Make sure that the tank contains enough fuel to start the engine.
Step 2
Read the battery voltage using a voltmeter and make sure that it has enough charge to operate the starter motor. Your battery should have close to 12.6 volts with the engine off.
Step 3
Examine the connections between the battery and the starter and make sure that they are tight and clean. Loose or dirty connections will prevent proper current flow.
Step 4
Inspect the fuel system and verify that fuel is reaching the fuel injectors. If possible, pull one of the fuel injectors and check for fuel spray; also, you may use a nod light connected to an injector connector and make sure that the vehicle computer is sending electrical pulses. If there is no fuel reaching the engine but the injector is receiving voltage, then check the fuel filter for clogs. If the filter is more than a year old, then consider replacing it. Troubleshoot the fuel pump if necessary.
Step 5
Check for spark in the ignition system. Pull one of the spark plug wires, connect a spark tester to the wire and ground it to the engine. A bright blue spark should jump the tester gap as you crank the engine. Otherwise, you might have a problem in the ignition system. Troubleshoot the spark plug wires, ignition coil and the rest of the ignition system if necessary.
Step 6
Measure the spark plugs' gap with a wire feeler gauge, if you installed new plugs or they are two or more years old. A plug with a wider gap than the factory calls for will produce a weak spark, unable to ignite the air/fuel mixture.
Step 7
Examine the timing chain. A worn out or jumped chain will fail to synchronize pistons and valves and prevent the engine from starting.
Take your Explorer to an auto shop and have them check the compression and troubleshoot for a possible engine mechanical failure if necessary.
Items you will need
Voltmeter
Nod light, if necessary
Spark plug tester, if necessary
Wire feeler gauge, if necessary
