How to Diagnose a Ford Focus That Will Not Startby Dan Ferrell
A no-start problem in your vehicle may be caused by one or more systems in your car. It could be as simple as a loose battery connection or as complicated as an engine mechanical problem. There are a few most-common causes you might encounter in a no-start problem with your vehicle.
Check the Battery
Turn on your voltmeter. Set the meter to the 20V range.
Touch the negative and positive battery posts with the black and red voltmeter leads respectively. You should get close to 12.5 volts. If not, recharge the battery or replace it.
Make sure the battery posts and terminals are clean. If necessary, clean the posts and terminals with a 1 tbsp. of baking soda mixed in 8 oz. of water and a soft brush.
Remove the two vent caps from the top of the battery using a screwdriver. Check that the acid level is right at the bottom of the fill rings. Add battery acid or distilled water as necessary. Replace the vent caps.
Check the Starting System
Make sure the pinion gear on the starter is engaging and turning over the engine. If the starter pinion is engaging and turning the engine, go to Step 4. If not, go to Step 2.
Remove the starter.
Turn the flywheel using a flywheel turner. If the flywheel turns without difficulty, you might have a problem in the starter system. If the flywheel is difficult to turn or does not turn at all, you have a mechanical problem and should have an auto technician inspect the vehicle if necessary.
Check all the starting system wiring from the battery to the starter solenoid and the starter. Make sure the connections are tight. Fix as necessary.
Check for Fuel
Locate the Schrader valve on the fuel manifold rail. The valve is similar to an air valve on a bicycle tire and is close to the first fuel injector on the inlet fuel line.
Cover the valve with a shop rag and depress the stem inside the valve with a small screwdriver. Use the rag to catch the squirt of fuel. If there is fuel in the fuel line, go to the next step. If there is no fuel, you might have a restricted fuel filter, fuel line or a bad fuel pump. Change the fuel filter if necessary or have the fuel system checked by an auto technician.
Re-install the fuel injector and unplug the injector electrical connector.
Plug a nod light on the injector electrical connector.
Have a helper crank the engine as you watch the nod light. If the nod light does not flash, there is a problem in the circuit and needs further testing by an auto technician. If the nod light flashes, the circuit is working properly.
Check the Spark
Disconnect one of the spark plug wires.
Connect a spark tester to the spark plug wire.
Hook the other end of the spark tester to a good ground on the engine block. A bolt or bracket on the engine will provide a good ground.
Have a helper crank the engine. You should see a bright, blue spark jumping the gap in the spark tester. If not, you have a problem in the ignition system: Either a bad spark plug wires, distributor, ignition coil or ignition module. Have the ignition system checked by an auto technician if necessary.
Remove the spark plugs one by one using a ratchet, ratchet extension and spark plug socket. Check the plug gap with a wire feeler gauge. Compare the gap with the specification on your car owner's manual and reset it if necessary.
Items you will need
- Photo courtesy of Dragon695 at Wikipedia.org.