If you have fuel at the filter housing that pumps/squirts out as you crank the motor, your mechanical lift pump is ok, turn the key to the run position and under the hood, remove the pig pink wire from the top of the injection pump, you should hear or feel the solenoid deenergise, then click again when you reconnect the wire. If that works, try cracking/loosening slightly an injector line at one of the injectors BE CAREFUL NOT TO LOOSEN TO FAR AND BE SURE TO WEAR GLASSES then have someone crank the motor over and see if you get fuel at the injector. If you have little or no fuel coming out at the injector it could be a bad injection pump.