I am scared to admit this in this croud but I'm a diesel mechanic. Have you done a fuel flow test before and after the Injection pump? using the decompresion valve crank the engine over for 20 seconds. if you have good steady flow then check after the pump. if both injectors are getting steady shots of fuel then its the exaust. if you have fuel problems after the pump its an easy removal and get it rebuilt. they break springs and cause low injection pressures.
