APP sensor 1 should start at .5V and increase as throttle is opened.
APP sensors 2 & 3 should start at 4V -4.5V and decrease as throttle is opened.
You should be able to see this with your scanner. Voltage changes should be gradual with no sudden spikes or dips. Voltages are approximate and...
If it didn't try to start with the spray in the intake, you may have other problems. What did you shoot it up with? It should try to fire off starting fluid whether it is getting fuel or not.
I always thought the flow was from the outside of the filter to the center. If I screw that out of mine, I can see straight down to the stand-pipe for the heater and outlet.