How do you check the solenoids to see if they're working correctly… beside blasting down the local the neighborhood Tn'T track

 

Nitrous just blip the wot while armed and you should hear a click with bottle off. With bottle on you would see or hear nitrous flowing....
Fuel same type of thing, a clicking and would see fuel coming out if there is pressure against the noid.

Do not spray either into a non running engine.
Ricky