We are doing this check on the first flight of the day...
Start the left engine first, switch OFF the fuel pumps (both!) and then wait for the "Right Fuel low Pressure"-Message. When the message appears swith on the fuel pumps again and start the right engine.
If the message doesn't appear after around 15 seconds dry-motor the right engine. If it's not comming ON after the dry-motoring the check-valve test failed, and as far as I know this is a NO-GO item!
After the first flight you have to shut down the left engine first, thereafter switch OFF the fuel pumps and wait for the "Left Fuel low Pressure"-Message...
Parkbremse was faster than me.... ;-)