1995 940 2.3lpt fuel pump operation

Just refitted injectors after clean. To try and get rid of the trapped air in the fuel rail before the first start, I planned to get the fuel pump running longer than normal during the pre start. I attempted to do this with the engine stopped, ignition on and pulling a vacuum on the fuel pressure regulator. ie simulating high intake vacuum at idle and fooling the regulator to drop the rail pressure by returning fuel, and hopefully the trapped air, back to the tank. Fuel pump just ran for normal 3 sec ! and no more ? Have I got the operation of the fuel pump wrong or is something not right with my fuel pressure regulator ? Richard

Pump. 

Fuel pumps will not run unless engine is cranking or running.Pump relay needs ignition pulses to remain active, hence the 3sec run only. This is done this way for safety reasons i.e. no engine turn no fuel runs. Paul.

Paul, That's a relief. But the Starter did not half take a beating to get rid of the air !!! Thanks, Richard