Spoon Sports 5/13/2011When the engine will rotate but, will not start, it can typically be attributed to one of two causes:
1. Lack of fuel
2. Lack of spark
This is where a fuel pressure gauge, a spark tester, and a digital multimeter are essential. For the most part, these two problems can be diagnosed independently of each other. However, there are several failures which will prevent the fuel pump from running and cause a no spark condition.
Testing for Lack of Fuel
As I mentioned before when testing for lack of fuel is is almost essential to have a fuel pressure gauge. You may test for fuel supply by removing the end cap from the fuel rail, installing a hose, and direct the open end of the hose to a catch pan. However, even if you get fuel from the rail during testing there is no guarantee that the fuel pressure is adequate to start the car. In lieu of a pressure test, fuel pump delivery rate test will at least give you an idea of the condition of the fuel pump.
Testing For Lack of Spark
The first step in testing for lack of spark is to verify that a no spark condition actually exists. A simple spark tester available at most auto parts stores is very handy here. I recommend removing the fuel pump fuse to keep the fuel pump from running during spark testing.
Disconnect one of the plug wires and connect the spark tester in series with the spark plug. Crank the engine and look for spark. You'll see the spark pulsing inside the tester as the engine turns over.
If there is no spark at the spark plug, disconnect the main lead from the ignition coil to the distributor cap and connect a spark tester in series with the coil wire. Crank the vehicle and check the tester for spark to the distributor.
If you get good spark at the main lead to the distributor and no spark at the spark plug, the distributor cap and/or rotor is bad and should be replaced. If there is no spark at the distributor main lead, proceed with ignition troubleshooting