What would make a 2000 dodge neon not fire?

oil fouled plugs because the grommets are bad in the plug tubes. if not, could be bad coil pack or ignition control module. may also be the crank sensor. use noid light on injector harness and see if it flashes when cranked, you will know if the computer is sending message to pulse injectors. check for fuel at the schraeder valve on the fuel rail after you turn key and hear fuel pump kick on for a few seconds to verify fuel pump works. put a spark tester on a plug wire and crank, does it have any spark. if no crank sensor signal you will have no spark or fuel injector signal. may also be a broken timing belt, you can do a compression check or remove valve cover and spark plugs and grab the serpentine belt and rotate engine by hand and watch to see if valve train moves while rotating the engine. less likely could be fuel pressure regulator on top of the fuel pump. make sure the fuel pump fuse and relay are good and also check the asd( auto shut down ) relay is good, use a volt meter and jumper wires along with the help of a haynes repair manual. with good fuses and relays you need good spark, fuel at correct pressure and good compression. a blown head gasket will not give you good compression. there are alot of reasons a car will not start, rule things out one at a time. a compression check will rule out timing belt and head gasket at same time.