You don't need smoke. Once the system is charged use 'Simple Green' and a spray bottle and start at the canister. You can dilute it 10 fold. Spray everything down and you will see it foam around any leaks.

 

Now we’re getting somewhere. But we’re talking two solenoid valves here. What state should they be in? Ignition on? Off? Or at this point should we have just replaced the two solenoid valves to no avail and are looking somewhere else?

What’s the appropriate pressure?