there is no volume spec. only pressure. but with a truck that wont even crank over, testing that wont get you far.
when you checked the fues did you pull them out and look at them or did you use a test light? if the latter please do the former.
next have you tried to get the engine to crank by using the connector near the passanger side battery?
have you check for network communacation concerns? does the cig light work. is there power and ground at the dlc?
does the dash light up all the lights it should have?