Farmall model M butane tractor

I have a 50's model farmall model M tractor that runs off butane, it's been sitting under a shed for about 15 years and I would like to get it running, we drove it under the shed so I know nothing is damaged, but would like to fire it up, what all do I need to do to be safe about it ..don't want this to 1. Run wide open when it fires up or 2. Explode and kill me, HELP ME!! haha don't really know much about these forums so if you need to email me at [email protected]

Working with propane is a different than gasoline. It is under pressure. Not only is there fire danger, the liquid is extremely cold and can cause frostbite. The vapors tend to settle to low enclosed places, so if this is an open shed, and there are no sources of ignition, you will be OK.

Now would be the time to do your initial start up preparations, good hot battery, crank the engine through, might shoot a little oil in each cylinder, check for compression, check for spark.
Remember, electrical arcs are a source of ignition, if there is a propane leak don't be cranking the engine or using jumper cables, etc.

Do you know if it still has fuel in the tank?

If you think there might be, find the shut off valve, be sure it's closed. Follow the line from the valve, it will eventually lead to the regulator. Loosen the line on the tank side of the regulator and crack open the tank valve. You should get a good flow of liquid propane that will immediately vaporize and boil away. Close the valve and retighten the fuel line.

If the tank is empty it will have to be removed, tested, and certified (or replaced) before it can be legally filled. If there are any rubber flex lines, they will probably be rotten and should be replaced.

Once you have fuel, open the valve, let it sit for a few minutes while you check for fuel leaks. Small leaks will be hard to find, usually there will only be the smell of propane to track down. Soapy water (kids blow bubbles work well) will help. Major leaks will be obvious.

On the low pressure side of the regulator will be a line going to the throttle body. Locate the air intake duct, coming from the air filter. Remove the duct from the throttle body and be sure there is no fuel dumping into the throttle body. If there is a fuel shut off solenoid valve, the ignition switch will need to be on for this test. If there is fuel dumping into the throttle body, the regulator will need to be rebuilt.

You were concerned about engine runaway when starting. While you're at the throttle body, locate the throttle linkage. It will work just as a carburetor would. With the throttle lever in the idle position, the throttle plate will be closed against the idle screw. With the throttle lever in the fast position, the throttle plate will be spring loaded to the open position. You should be able to push it closed against the governor spring, it will return to open when released.

Now, see if it will start. Some of the older models had a primer button, use it sparingly. A shot of either might get things going, but be careful.

If it starts and runs, great! If it runs poorly be sure there aren't other problems like stuck valves or corroded ignition points. If you plan on actually using the tractor, a regulator rebuild would be advisable considering the time it has sat unused.

Hope you get 'er running!