BMW Repair: no go, bosch fuel pump, engine mechanics

Question
i have an 1983 e30 318i, brand new external bosch fuel pump and new fuel filters.
starts sometimes, runs for hours, then wont start again. i was told by a mechanic that he suspected the fuel pump to be faulty, is there any other mechanical issues that should be taken into consideration.?  

Answer
Rhys,
 Do you have spark?  Do you have fuel pressure to the engine?  
 Mechanics dont want to mess with little jobs too often, they dont make them much money, and they cant take their sweet time with fixing them.  
 You need to check for fuel pressure to eliminate the fuel pump as the problem.  Pull off the fuel line running to the injectors and insert it into a drink bottle.  Have someone try to start the car and watch for fuel to squirt out.  You just want to check that the pump is working, so no need to fill the bottle with gasoline.  If it's working replace the fuel line and scratch "fuel pump" off the list.  If it's NOT working, then you need to check the fuel pump's wiring.

 Then check for spark.  If you have no spark then that's your problem.  How long has it been since you have done a tune-up on the car?  It could be in need of ignition components.

 Good luck,
 Josh