THE EXPERIMENTAL PROPANE CONVERSION GENERATOR
Living out in the country has its benefits in many ways but it also has some drawbacks, not many, not serious, but drawbacks nonetheless. One of those main drawbacks is the risk of power outages when the skies so much as dribble or the wind so much as farts for a second. An errant tree will come down over a power line and have power out for hours or more while power crews try to locate the damaged line and repair it. Because of this you have to have a means of backup power out here otherwise you will have to be ready to spend many a night in the dark when the weather wants to go bipolar.
In our case we have a couple of portable generators that are each big enough to handle a heavy load in the house (fridge, freezer, TV, internet, couple of lights, AC). Because these generators aren't always running, it is sometimes necessary to run them just to keep things loosened up and to purge old fuel from their systems. Sometimes we may forget to do this routine maintenance and the gennies will sit longer than usual before it gets started. It is during these conditions when I find out that the carburetor is gummed up or otherwise messed up and not allowing the genny to run right.
We had a situation just like this during a storm situation where the power was out and wasn't going to be back on for a good while, like the next day. One generator, the bigger of the two, would not start at all except on starting fluid then die once that vapor was exhausted. Undeterred we moved to the other genny and got it started. It however had always required a shot of starting fluid to get it started but once started it would stay running. We were good for a while but then near the end of the night the thing had crapped out. After wrestling with it I was able to get it started again. After a couple more episodes of the genny crapping out I come to find out that the fridge cycling on was drawing down on what was a compromised genny, causing it to die. Normally the unit would handle the load but not now, the carburetor was crappy.
The following morning I had decided to try a little test. Knowing that these same engines would run on propane, I did some quick research on running small engines on propane and decided to get to work. I had an old regulator I salvaged from a broken grill. I took the regulator and hooked up a couple of pipe adapters that allowed me to terminate the end of the regulator line with a 1/8" NPT nipple.
The next thing I did was disconnect the fuel line on the carburetor of the genny. Since we're not going to be running on gasoline, it wouldn't be needed. I did a test where I suspended the pipe nipple in the throat of the carburetor and cranked the genny over. I was able to get the unit to sputter to life and eventually balance out with some adjusting of the regulator and tank valves. After a while running the unit I decided to try something else.
Since the fuel line was disconnected from the carb on the genny, I took a short piece of rubber fuel line and plugged it to the 1/8" nipple then took the other end of the hose and plugged it up to the input port of the carb, setting things up the same way it would've been with the gas line. I repeated the same procedure, turning the gas on just a little bit so I don't "flood" out the engine with pure propane. Even though propane is just a vapor, you can flood the engine where there isn't enough O2 molecules mixing in with the propane to allow for combustion.
After turning the gas on a little bit I pulled the cord and after a couple pulls got the engine to pop right off easily. It held an idle so I slowly worked the regulator, opening it up until the engine ramped up to normal running RPM. One thing I did notice is when I kept trying to open the regulator, past a certain point the engine RPM's would drop off like the regulator did something weird where it would not allow gas to flow any more after that point. Not that the pressure remained constant, it just disappeared. So with that I had to keep the regulator valve opened within that "sweet spot". When I got the engine running at what sounded like normal running RPM I plugged everything up and lo and behold the genny ran all of that stuff, cranking out power with only a slight drop in RPM as the machine was put under the heavier load of all the devices. We ran the genny for the whole time we needed, only shutting down when we left. Since there was no way to further regulate things in our absence, we didn't want to leave things running since anything can happen that'll have propane just leaking on out and one good backfire could cause this gas to ignite from the carburetor making for a bad day.
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