Car will occasionally not fire, but keeps cranking

[318iskid]

My '91 318iS usually will start up fine, but maybe 1-3 times a day, it wont fire, it'll just keep cranking and I have to be push started. It has become a big pain in the and I'm terrified of driving it anywhere. Any help as to what the problem could be would be greatly appreciated!

[roguetoaster]

After it starts does it exhibit any odd behavior?

Clearly you have one of two problems, no spark or no fuel on start up. No spark means a bad sensor, maybe horrible plugs or perhaps a small wiring issue. No fuel probably is down to the fuel pump.

Just as an afterthought, have someone else crank the car while the hood is open so you can see if the belts are rotating thus making sure the problem is not starter related.

[jntar]

Last time you changed the fuel filter?