I have a 10lb bottle in the boot(trunk), I open the bottle and gauge reads anywhere between 600(first thing in the morning) and 900(the bottle nice and warm)psi I use the system and then close the tap on the bottle. The gauge, as I understand it, shows the pressure in the feed line because it reads from after the tap and before the solenoid. After about 6-8hrs the gauge is reading as low as 200 to 0 psi. The solenoids are never operated without the gas being on and none of the line or the tap are frosting up(so I'm guessing no leaks). I'm wondering were the pressure and the gas in going??

 

It sounds like a slow leak. You have to listen closely to find out where your leak is comming from. You can also put some soapy water in a spray bottle and then spray everything until you find bubbles.

 

Sounds like a job for the morning then, cheers.