G-VI Propane Regulator

This is going to look like an extremely dumb question to anyone familiar with LP/Propane systems, but I have never used or worked on a propane system before, and neither has my local mechanic.
We are thinking there is something wrong with the regulator or carb because it does not shut off the propane flow when the tractor is turned off. One has to turn off the valves on the fuel tank itself to stop the flow. The mechanic is thinking something in the regulator or carb should stop the gas flow when the switch is turned off. This is a Ensign (model R) brand regulator and carb.
Are we correct in thinking the regulator or carb is not working right? If so, what might be the problem? Are there any shops in the upper Midwest that fix these old Ensign regulators?

It?s the solenoid : make sure there is power there and if so the solenoid is bad , regulator does just that, regulates flow or pressure:

Welters in Verona, Missouri can do that.. 417-498-6496

Fuel flow should stop and if it doesn't the problem is in the vaporizer/regulator unit. The carburetor has nothing to do with it and there ain't no solenoid. The vaporizer is to make fuel "available" to the carburetor, not deliver it. Engine vacuum draws fuel from the vaporizer. If fuel is passing through the vaporizer when the engine is stopped, there's a problem with the needle and seat in the unit. Yes, there is a needle and seat. Unlike a common needle and seat however, there is no float. There's a spring and diaphragm responsible for moving the needle. Get any IT manual that addresses any tractor with that model vaporizer and it will instruct you as to how to bench test the unit.

Curt Cooke gave you the right answer. It's the convertor/regulator. A rebuild kit will make it like new again. They aren't complicated.

I had the same problem with my GVI, maybe. In my case the tractor would run fine, but when I shut it off there continue to be a gentle passage of propane vapor through the carb and out the oil bath and air intake. Is this you case? If so the issue could be on the low pressure side of the regulator instead of the needle and seat.

You will need to remove the regulator from the tractor. Remove the eight screws that hold on the back plate. Now Very carefully remove the back plate which holds to a cork gasket and a thin rubber diaphragm. To my knowledge no part are available for this unless salvage or new old stock. After removal of the back plate and diaphragm, remove a brass plate gently. This will reveal the low pressure valve which is held in place by two screws. In my case, a small amount of foreign debris kept this valve from seating. Once clean the valve worked.

You may test bench test the unit by attaching to a propane bottle. Also, there is a 3/8 hose that goes from the carburetor to the regulator. Attach a comfortable length of hose to this fitting on the back plated of the regulator. With the gas on there should be no gas passage. When you pressurize this 3/8 hose by blowing with your mouth, the diaphragm moves and opens the valve and vapor passes through the regulator. With no pressure on the diaphragm, gas should stop. Call me with questions. Jim 660-322-1045