Hi theedster. Welcome to the forum. The first thing to do when it doesn't start is to listen for the hum of the fuel pump. You should hear it run for one second after turning on the ignition switch. If you hear that hum, the fuel pump is working. They rarely quit while driving. When they fail, it is almost always a failure to start up.
The pump will turn on again during engine rotation, cranking or running. If it does not, it is most often because the Engine Computer is not turning on the Automatic Shutdown (ASD) relay in response to missing pulses from the camshaft position sensor. That sensor can fail completely but it is very common for them to become heat-sensitive and fail while driving. Hearing the pump run while cranking can be difficult. A better method is to use a cheap digital voltmeter to measure the voltage on the dark green / orange stripe wire in the connector for the coil pack or either of the small wires on the back of the alternator if you can reach them. You should see around 12 volts for one second after turning on the ignition switch and again while cranking the engine. If it doesn't come back during cranking, suspect the camshaft position sensor.
When it doesn't crank, do you hear one kind of loud clunk from the starter? If so, suspect worn contacts in the starter solenoid. They can be replaced for 20 bucks, but most people just replace the entire starter. This is particularly common with the small silver Nippendenso starter.
Tuesday, June 8th, 2010 AT 1:33 PM