My Mercedes 380SL will not start.

The car has been set up for some time.  The only way to get it started was to pour gas into the throttle body.  The engine would run for 3-5 seconds and sounded very good.  We were unable to get fuel from gas tank to motor. After installing a new fuel pump we tried to crank the car and it would not crank. After a week went by we realized we had the power cables reversed on the fuel pump.  After correcting this the car started right up.  After 30 seconds I turned the car off and cranked it again.  It started right up.  We thought we solved our problem.  We turned the car off and checked all of the fluid levels.  Everything looked good so we tried to start the car again.  It would not start.  even pouring gas into the throttle body it would not start.  We replaced the spark plugs thinking dirty gas messed the up and it still would not start.  We are getting fire to the coil and plugs.  we took the fuel line off of the injector and turned the key and gas came out good so we are getting fuel.  We cannot understand why it will not start now.