Converting a generator to run on propane

A step by step instruction on how I converted my generator to run on propane as a back up 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 thats because I wanted new parts. If you had the parts laying around you could get out of it cheaper.

Step 1 Warnings

WARNING 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. Use this instructable at your own risk!!

Comments

[emiller17]

Interesting I didn't realize you could convert a generator to a portable gas generator. So cool!

[simonkoenig911]

i was just wondering about that safety shutoff valve... if you had an engine with an alternator on it, could you use that to power a solenoid valve, so the minute the engine stops turning, the propane supply would turn off, and you could have a manual override button for starting. anyone got any ideas on this?

[The 4th Doctor]

sounds like a great idea to me, on any generator you could just run it off of the wall voltage output too. i cant find any cheap solenoid valves though.

[trike road poet]

To end the backfire/explosion worries, just go to a local welding shop and buy a flame arrestor, a simple device used on cutting torches to prevent flame burning back up a torch hose and into the tank. The one for the Acetylene tank would likely work well, and the guys at the welding shop can aid you with selecting the right fittings to make the arrestor fit into your rig.

[mpikas]

I don't get it, why go to all this effort?  You could just drill and tap a hole someplace in the casting and leave the carb functional, maybe put a shutoff valve in he gas line. 

That way you have a setup that can be used for either, shut off the gas and run it on propane, or close the propane valve an run it on gas...

[Rainh2o]

first I didn't want to drill a hole in my airbreather.  Second I had the old carb laying  around and it was trash and just  wanted to see what it would take to make it work like this.  No other reason.

[mpikas]

Yea, i get that you had the junk carb, but my point is that you didn't need to even mess with that.

A MUCH better way of doing this is to find an open spot in the carburetor casting, intake casting, or maybe make a spacer 3/8-1/2" thick using the carb gasket as a pattern (could be out of anything, aluminum would be best, but lots of plastics will work, as will any decent wood (soak it in "aircraft dope" or model airplane stuff from SIG, thin epoxy or a dozen other things to seal it), then drill a hole in the side of it and tap it for an 1/8" NPT thread.  Then take a brass hose nipple with a 1/8" NPT thread, solder, epoxy (JB weld...) or braze a short length of tube into the opening on the threaded end, and then crush the end so it acts to spray the propane into the throttle bore when threaded into the hole in the spacer.  The crushed end will give it some velocity and turbulence so it mixes better and you shouldn't have to worry as much about throttling the airflow in, it should run well over a broader range of mixtures.

Hook up your regulator + needle valve to the hose barb with a length of hose making it convenient and go for it.

[menahunie]

I agree.
My generator I drilled and tapped a hole in the intake manifold; similar to the one you see in the video.Took the carb off first to make sure I got the chips out.
I used a piece of propane hose clamped to the fitting screwed into the intake manifold with a male quick connector ( i stick a rubber cap on it when not hooked up ) to hookup the generator to the propane regulator. I also use a electric cut off valve that uses 12v; ( I use the 12v port on the generator - stops no 12v ) - no 12v it closes and turns off the propane. I use an adjustable regulator at the propane tank.
If I am using the generator camping or work I run it on gas or propane depends where I am. My truck runs on propane so I have around 45 gallons when truck is full. I just screw the fitting onto the fill port of my truck using high pressure propane hose to a regulator and hook up to the generator..

[Rainh2o]

Your right that would work.  Might be easier for some who knows.  I just WANTED to use the old carb to do it.  No real other reason then seeing if I could make it work.  Kept the carb out of the land fill and kept me entertained for a weekend.  In most simplest method you could just drill a hole  in the top of the air breather casing and stick the regulated flow of the propane into that and make it run.

[menahunie]

you could have left the butterfly in to control air flow...

[derhul]

Good idea!!! I never knew you could do this to portable gas generators

[markger14]

where did you get your propane? is it from lpg tank?

[Rainh2o]

Yes a BBQ grill type tank

[Phantasmagoric]

Wow, pretty cool. I'm trying to find stuff on converting small engines to run on alternative fuels to do a project for school... Would this be safe/easy enough to do on a lawn mower engine?

[Rainh2o]

Thats basically what my generator engine is, a lawn mower engine.

[kubbetta]

It is very good project.I managed to convert a 2 stroke generator,but the problem is how to lubricate the piston, as before it worked on mixed petrol and oil.Any ideas

[kaado505]

well you could put the propane in the air intake and where the gas used to flow you could put the oil and turn the throttle low so it only lets a little oil in then control the speed by a regulator for the propane

[Rainh2o]

you would have to devise a way to inject or drip oil into the air stream after the propane enters the carb

[compaq1501]

 i know its been a while since anyone commented on this instructable, but i wanted to convert a weed whacker/eater to run on propane from one of the small camping stove sized propane tanks. What i was wondering is, is it possible for the motor to back fire and ignite the propane? This is for an experiment so it wont actually be cutting weeds, at least not yet, and i dont want to blow up one of the tanks. Did anybody use some kind of bubbler or flash back arrester or anything?

Thanks in advance to whoever can help 

[Rainh2o]

Sorry to take so long to respond to this.  I wouldnt use a weed whacker engine for this. You have to mix oil and gas in a 2 cycle engine and by running it on propane through the carb, you would be removing the oil, and it wont run very long at all, maybe 15 mins before it locked up.

[compaq1501]

 My weed wacker is among the rare population of 4 strokes. there is no need to mix the oil. I tried to start the weed wacker motor by placing a propane torch into the carb opening (not the air filter) and pulled it and it wouldn't start or even fire. I then warmed it up with gas and got the same result..

thanks in advance for your help

[Rainh2o]

OH...OK..sound like maybe there was too much propane?  Maybe it wasn't getting enough air?  If its a 4 stroke, it should work.  I know it took a bit of fiddling to get the air/fuel mixture just right for my generator.  The smaller engine might be more sensitive to the mix.

[compaq1501]

I dont think it was too much, becasue i was doing it outside and after i had pulled it once, it should have dissipated a little. I think that maybe the motor is a lower compression and just a cheap little motor. I think it was designed to run just good enough for whacking weeds.

Anyway thanks for your help...

I think i'll try a bigger motor maybe...

[hendrosutono]

If you get rid of all the carb component and all the hole, why don't you just replace it with the same diameter plain tubular pipe, weld a plate shape like the intake on one side as an anchor and bold it up. Then put the venturi in the midle. That way any time you want to go back to the gasoline, you just put the carb on.... ;-)

[Rainh2o]

I didnt want to just throw the old carb away. This was built out of an extra carb I had laying around. I put he original carb back on after this experiment and then put the propane carb in a box on the shelf in case I ever want to use it.

[hendrosutono]

would you like to give comment on my instructables? it's also about converting generator...

[qparker]

you could, but the carb I had was shot and I wanted to do something unique to it, besides just toss it

[dsandds2003]

This looks similar to an idea that was posted on the Internet before. But it was removed for safety reasons. Something to do with using a regulator because for some reason their was a danger of explosion without a regulator.
I have been looking for a similar idea for quite awhile. Glad I found it here as I want to explore the prospects of this idea a little further. Thanks for posting it.

Keep up the great work!!!

[qparker]

I tried a hotter plug and it helped a little but the problem is still there I also tried a colder plug and it wouldn't run at all once the engine is running I tried changing the fuel/ air mixture but that didn't help Any other suggestions would be appreciated

[qparker]

I finally figured it out:
 I got the engine running and covered all known holes on the carb, spraying a little bit of starting fluid on various spots of it and found that the gasket between the carb and the intake manifold was leaking air, so I used some silicone and that fixed all my problems!
 I can now mow my entire acre of lawn on just one of those bottles used on a camp stove:)
Thanks for all the help,   This Instructable is GREAT!!

[Rainh2o]

hmmm...maybe your rings are worn out and you have very little compression? You might check the compression. Not sure what they are supposed to be in these little engines. I have also seen a shear key that holds the flywheel to the crank shaft be "bent" out of shape, almost sheared in two once, and that caused an old mower of mine to back fire and run rough. By allowing the flywheel to slip you change the timing of the spark either forward or back due to the magnet on the flywheel advancing or retarding the spark timing. its a pain to check but thats the only other idea I have at the moment.

[qparker]

I checked the compression when I put the hotter plug in and it was about 115-120 psi I think that would be plenty... I'll check the fly wheel and see if it is loose Thanks again for all the help

[rhoula]

How long does the generator run on a full propane tank? Thank you

[Rainh2o]

I dont know. I never ran it for more then a couple of hours and see any noticable use of propane. I am assuming it would run it for 7-9 hours since thats what my generator will run on a full tank of gas depending on load and the"Mileage" isnt supposed to change much when you switch from gasoline to propane on a car.

[KronoNaut]

Can you use some type of solenoid to cut off the flow of propane if the engine dies?

[Rainh2o]

you could, but i didnt have a solinoid handy and dont plan on running this without being around, no real need to. It wouldnt be hard. Plan on using it out in the driveway and if it dies, the lights will go out and I'll know its dead. Also know enough to let the area clear a bit before trying to start it back up due to propane build up.

[qparker]

I'll check the spark, I changed the plug before the conversion, but i'll check it again, just to be safe, maybe put a hotter one in Thanks for the input.

[Rainh2o]

Another thought, might also check the flow and either richen it up or lean it out. Maybe after it gets warmed up it needs to be leaned out to run smoother.

[qparker]

Great help, currently have my lawn mower running on propane... the longer it runs the worse it runs, could the propane be freezing in the lines thus constricting the flow? please help, if needed i can send pics of my setup

[Rainh2o]

Might check the coil or magneto as they call it on mowers. It creates the spark, it might be bad and by getting hot, it doesnt produce enough spark? Also maybe a new spark plug. You should be able to see ice on the lines if the propane is freezing in the line...