I have the Merc silent choice with the air cylinders and last weekend I would open the exhaust no problem then go for a blast and by the time I had came off plane they would be closed, then I would open them back up again, I dont think there is an air leak but I havnt done a soap test........Doug

You have an air leak. Check for loose fittings. Open them back up and put dish soap on the fittings and look for bubbles.

Mine did the same thing. Would only hold pressure for a minute. The relief valve was leaking. I just removed, cleaned and reinstalled it. 10 minute job. Problem solved. The valve is so basic, I didn't see the need to order a new one and wait for delivery.

I agree with both replies, but with a long history with Mercury I to would check the relief valve on the air pump itself. These things are notorious for this. Remove it disassemble it clean it , put it back together and go boating. We have had to actually take that valve out and put in a pipe plug so some people with HP motors didnt have any problems while we had to get a new valve. The salt water got to it befoe we did. If you do this just be careful not to hold the button down to long and blow off an ail line .

Pwrbt33

If, by some chance, it turns out to be the air cylinders, I have 2 brand new ones I wont need.

Ahhhhh, excuse my ignorance but, where is the relief valve???

It is on the air pump itself. It will be on the tee were the air line connects.

Finally got around to checking this..........my pump doesnt have a "tee'' on it, it is just the pump, a fitting, then a single hose connected to it that goes to an electric solinoid with the air line coming out of the other side of it. I took the top off the pump (3 screws) and didnt see much to clean or service in there, wondering if I have a different set up than yours............reason it took me so long to check it..........changed trim tab indicator cables........NASTY!!!!!!!! Doug

My marina melted pistons in my motors because they did not properly hook up the silent choice! My motors are supercharged, exhaust backed up and the rest is history.

ttt