Need help setting pressure please!!

[Stallonepanerai]

Hello everyone,
I'm new to the forum and also home brewing. I just built a home bar and built a small kegerator. I got my new C02 bottle filled for the first time today. I bought a conversion kit from Kegco. Tank, gauges, hoses, faucet, etc. I cannot for the life of me set the C02 gauge to 10 PSI. I followed all the directions. Here is what I did...
-C02 tank valve closed
-Connected gauges to bottle. Valves and gauge closed
-I turn the tank all the way on
-With the supply line to the keg closed,
I set the pressure to 10 PSI. I wait about 15 mins to make sure it stays at 10 PSI. It does.
-I open the valve to supply the keg with C02. The gauge goes down a little bit but goes back to 10 PSI right away. Without dispensing any beer I wait 15 minutes and check the pressure, and BAM its
Between 15-20 PSI. I have repeated this about a dozen times. I also pulled the release valve on the gauges to release the pressure and it builds right back up again.
Even if I set it to 8 PSI it builds back up.
I tried everything I can think of. I pour a couple beers and the pressure keeps going back to 15-20. Im wasting beer and C02!!
Can it be that the keg is pressurized more than 10 PSI and its adding pressure to the system? The keg is a 1/4 tall Miller Lite. At least it's cheap beer but I would rather drink it. If it matters the beer supply line and the CO2 line are both 5'. Everything is brand new just unboxed today. Can someone please let me know what I'm doing wrong??? I would really like to get the pressure set so I can balance the system.
Nice meeting everyone and thank you
In advance for your help!!
Corey-

 

[Pkrd]

The beer is already carbonated at a higher pressure than the 10 you are wanting to use. It's going to keep going up until it loses enough carbonation to get down to 10.

Is it pouring OK?

 

[Stallonepanerai]

With the charts I have been using to balance the system I currently have 5' of 3/16" line now and I need 8.5'. So right now it pours very fast and lots of foam. Hopefully when I add the 3.5' of line the restriction will slow down the pour. Is it normal for the keg to be pressurized that much? Also is it normal for the keg to loose enough pressure and level out at the 10-11psi that I need?
Thank you for your reply!

 

[camonick]

With the charts I have been using to balance the system I currently have 5' of 3/16" line now and I need 8.5'. So right now it pours very fast and lots of foam. Hopefully when I add the 3.5' of line the restriction will slow down the pour. Is it normal for the keg to be pressurized that much? Also is it normal for the keg to loose enough pressure and level out at the 10-11psi that I need?
Thank you for your reply!

Commercial light lager kegs are carbonated with approximately 15 psi at 38°, ie. ≈2.8 volumes. If you want to maintain the same carbonation the beer was shipped at, you need to maintain the same pressure and temperature or consult a carbonation chart to maintain the same volumes of CO2. Why do you “need” 10-11 psi? You always choose the temperature and carbonation level you desire in your beer and adjust your system to balance at that. You don’t choose a random pressure and expect good results. If you’re using standard 3/16” vinyl tubing, plan on at least 1’/ psi for proper balance (more doesn’t hurt, you can trim shorter if necessary). I would suggest starting with 15’ of beer tubing.

Edited to add: Length of gas line is irrelevant.