Silent Choice not working right
 

I have a stock 1997 Scarab 29 with twin 350's and it had the thru hull exhuast with prop switch option to quiet it down.
However, when I turn on the thru hull it comes on properly but after about 3-4 minutes its back thru the prop again. It wont stay in the loud position.
Any advice?

if its a air pump system one of your lines leaking, or the solenoid is leaking. pump up the system and get a squirt bottle with water and dish soap in it and squirt it at all hose and fitting connections and you will find the leak.

if its a electric system then i have no idea!!!!

Check your relief valve at the pump. Those tend to get dirty and not seal, allowing the air press to bleed down. A simple cleaning usually fixes it.

Thanks Guys! I will try it