Why would a Chevy Astro Van turn but not start?

try the ignition control moduale under distributor cap . Any gasoline engine needs fuel and ignition to start. You can check the coil wire (that's the part that went bad on my astro) and the fuel pump, as well as the ignition module. Listen for the "whirr" of the fuel pump when you first turn the ignition. If you don't hear the pump pressurizing the system that may very well be your problem. Try having someone kick (or rubber mallet) the bottom of the fuel tank while trying to start the motor. This sometimes is enough to get the fuel pump going again when it is going bad.