A step by step instruction on how I converted my generator to run on propane as a backup fuel source. There a numerous reasons one might want to do this. You might need a cleaner burning engine. You might not want to store or carry large amounts of liquid fuel around, besides liquid fuel eventually goes bad, propane will not. Its easier to store large amounts of propane. In an emergency situation such as hurricanes and earthquakes, gasoline might not be available or if it is, it will be in high demand, propane usually is not.
I found several ways of doing it on the web but nothing that seemed permanent or cheap. They have kits to do this but I didn’t feel like forking out 100+ bucks to do it. This project cost me about 25 bucks and that’s because I wanted new parts. If you had the parts laying around you could get out of it cheaper.
Be Carefully this could be dangerous if the motor dies and your not around, the propane will continue to run and could possibly build up and you would have a nice explosion. The kits available commercially have a safety shut off or an on demand regulator that will shut the gas off when the engine dies or is not running so they will not flood the area with propane.
I run my generator outside on the driveway and know when it dies so I don’t have a problem with the way I did this. Besides, with the wind blowing, I would never have a problem with gas build up. NEVER run the generator indoors with propane or any other type of fuel for that matter. Propane is heavier than air so it will collect on the floor or near the ground when it is allowed to escape out of the tank.
I used propane generator conversion kits . It was shot and not repairable. It was physically the same size as the carb on my 10 hp generator and made by the same company. If you decide to use the carburetor off your engine be aware that this process is not reversible and it will make the carburetor totally useless for any other purpose. My advice is to obtain an old carb to convert for 3 reasons.
- If you screw it up and it doesn’t work, then you still have your original one to put back on your engine.
- If you decide to later return your engine to operate off gasoline, it only takes a min or two to put the old carb back on.
- If you will have a way to run your engine on two different types of fuels. Could be useful in a crisis when gasoline might become scarce.
You can obtain old carbs possibly by visiting a local propane generator accessories. They might give you one cheap if it cant be used on a gasoline motor anymore. Another source is to look for the same type of carb or engine that has a carb, on an old mower or some other engine that doesnt run anymore. Look on craigs list, garage sales, ebay, neighbors backyards, trash dumps etc etc… any carb that will physically fit your engine should work for this even if it is gummed up from gasoline. Possibly if its from another mfg, just as long as the mounting flange and openings are the same.
Remove the old float and needle valve
You first have to remove all the old parts out of the carb. First remove the bowl. Usually this can be done by unscrewing the bolt or jet on the bottom of the bowl. As you can see, this carb was pretty old and totally shot.
Next remove the float and the needle valve and spring. Most carbs you just have to remove the pin that the float hinges on and the float and needle valve come out all connected .
Remove the butterfly valve
Remove idle and mixture screws/jets
Removing the jet hole plate cover.
Primer bulb removal
Venturi Jet removal
Clean it up
Drill out the venturi port
Seal it up
Mount the carb on the motor. Be Sure to use a gasket between the carb and intake manifold. Connect the gas regulator line to the assembly and connect to a 20lb propane tank.
To start the motor, make sure the needle valve is turned off. Turn on the gas on the propane tank. Turn the needle valve about 3 turns and then quickly pull start the motor. After 2 pulls mine starts up and then I can adjust the running speed by using the needle valve. If it doesn’t start within a couple of pulls or you start to smell a strong Oder of gas, turn off the gas and let the area clear before trying again. Just watch for gas build up. Do it outside in the driveway.
When it starts adjust the needle valve for best running speed. You may need to slide the whole assembly into or out of the carb to find the depth the venturi needs to be for best results. After you find this spot, mark it on the tubing and then using marine epoxi or jb weld or some other high temp epoxy, epoxy the whole assembly where the venturi tube slides into the carb.
As soon as the weather clears up I will attach more picts of my final assembly and maybe a video on how well my motor runs and how I start it.
After messing around with this set up for a week or so, I discovered that the engine was getting too much airflow. I ended up making what I call a restrictor plate to restrict the airflow. In the video you will see the plate I made. I just mounted it to the front of the carb with one screw and adjust it according to the weather, colder weather I will have to restrict the air more, warmer weather I will have to open it up some. I set the plate so that the governor of the motor “floats” in the middle of its travel. On a generator you have to get it up to a certain speed for maximum power and frequency generation, without a tachometer I figured if the governor was about in the middle, it was running about the correct speed. Load tests of about 35 amps confirm the generator is able to deliver what it is supposed to without the motor dying or any other problems. It does load up but it never died. It was mentioned about the lines freezing up in one of the questions, I was not able to see any ice or signs of freezing, but the temp was about 20 degrees when I tested this thing. I don’t know what it would do in warmer weather. I let the thing run for about 2 hours with no problems. I also did away with the 90 degree elbow I mentioned earlier. I did not like the way the 1/4 inch line vibrated with the elbow on, so I ended up as you can see in the video just making a gental sweep into the carb.