Is the ISOL valve required to be open for engine start?

[Swagbasket 23]

Question is in the title. I find myself unable to start the engines when the isolation valve is closed, yet no checklist I have found says that it must be open for startup. 

[CRJay 428]

Technically, yes. It needs to be open at some point to allow bleed air from the APU or the running engine to reach the opposite engine for startup. 
 

But if your Bleed Valves selector is set to Auto it should take care of this automatically. You only need to worry about the ISOL Valve if you are in manual mode or in non-normal operations. The ISOL switch should have no effect if the Bleed Valves selector is in Auto. 

[JRBarrett 675]

As CRJay explained, as long as the bleed air selector is in “auto”, the isolation valve will operate automatically.

 

The bleed air system on the CRJ 700/900/1000 is an improvement over the older CRJ-200, where the pilots have to manage bleed air manually. On that aircraft, if the isolation valve is closed, you would not be able to run the right air conditioning pack on the ground, nor start the right engine.

 

The other thing that the automatic bleed air system does is to manage the main engine bleed valves. These must remain closed until the engines are running. If they are open (prior to engine start) the engine starter will not engage.

 

As long as you keep the main bleed air switch in the auto position, all valves will open and close in the proper sequence.