Posted: 7/17/2010 7:43:28 PM EDT
Almost two years ago, a few months before becoming a ham, I bought a generator. It is a PowerBoss by Briggs & Stratton, with 13 HP Honda GX390 engine (390 cc), rated 7 kw continuous, 12 kw starting, electric start, etc.
(Edited: Smooth A/C, no RF hash or buzz) I would pull it out every month, run it 20 minutes or so, and put it back in the storeroom. It has, until recently, run smoothly. Yes, I put in only enough fresh gas to run it a bit, and ran it nearly dry each time. Then I would close off the fuel valve and run it out. I took it out to use for Field Day and it ran rough. I had to pull the choke out a bit to get it to run smooth and not "hunt". I took it to a nearby Honda authorized service place. They sell and service Honda generators, outboard motors, and a number of other generators and outboards. They also manufacture boats. If you need a custom aluminum boat they are the ones to go to. They told me, and I was told the same by others, the problem I and others are having is due to ethanol in the fuel. Apparently the place where I get gas has recently changed to gas containing ethanol and that was the cause of the problem. They also said the engine would run fine on pure gasoline. The upshot is to use a fuel stabilizer, and if possible, use only real gas, not gas with ethanol. A ham friend and pilot said to use Avgas as it will have no ethanol. Also, I need to run it more often and longer when I do run it. The final thing... they increased the midrange jet by .001". The jet was not clogged, it was just too small for the fuel obtained here. The ethanol leaning the mixture could be compensated for with modern computer controlled engines but not with this generator. The ethanol was just enough to lean it too far. Richening the midrange fixed it. They still recommend using straight gas if I can get it. So, the generator is working smoothly now, and I'll give it a better test run tomorrow if it doesn't rain again. I've also picked up some Stabil and tomorrow will head out to the airport for some Avgas. 73 AFM |
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There's probably several easier places to get non-ethanol gas than the airport. Check over on the SF. Locally Marathon is pure gas at every grade, as is BP's 89 and 92 octane, and I think shell's good stuff. The fuel we have delivered to the house is the "mid grade", 90 oct. its a little more than the 87 but no corn squeezins in it. When we were getting the 87 it would suck up so much moisture during the summer to cause issues in the XYL's tahoe. Our generator runs like crap on "regular" gas, that happens to have ethanol too. it does pretty good on the 90. Never really though about it being the ethanol... -Slice |
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Gasoline burns at a 12:1 mixture, that is, 12 parts of air, by weight, to 1 part of gasoline.
Ethanol (grain alcohol) burns at a 9:1 mixture, by weight. Methanol ("wood alcohol") burns at 6:1 mixture, by weight. This is the kind of "alky" burned in some drag cars. The problem with Methanol is that in daylight the flame is invisible. At night it is pale blue. You can have your @$$ on fire, slapping out the flames, and no one can see it. Nitromethane runs at a 1.5:1 mix, by weight. Adding more nitro to the alcohol ("tipping the can") in a "fuel" dragster has the effect of leaning the mixture. The mixture must be richened. Adding Ethanol to gasoline has the same effect, that of leaning the mixture. But via the computer in modern cars, the oxygen sensor feeding information back to the computer, the throttle body or fuel injection should be able to adjust the mixture to compensate. But small engines are running a plain old carb. I would not have thought 10% Ethanol would lean it enough to cause this problem, but apparently it does. |
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Quoted:
Check with the airport and make sure there isn't any alcohol in the fuel. I'm no expert, and someone should correct me if I'm wrong, but I thought the FAA approved ethanol in the lower grade avgas. Like the 89 octane? The 100LL however is alcohol free IIRC. I'll check and make sure. Meanwhile, I seem to remember seeing a sign at one of the local gas stations, and for the life of me, I can't remember which one, that said, "No Ethanol in our gas." I'll find that station somehow. |
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Higher octane rating is a measure of resistance to detonation. Smaller engines tend to run smoothly on lower octane gas, but higher octane rating does not hurt. In other words, if your car runs OK on Regular, putting in Premium is a waste of money, but won't hurt anything.
ETA: By itself, higher octane fuel is not more powerful, hotter, more explosive. As stated, the octane rating is a measure of its resistance to detonation (pinging or knocking). But higher octane gas can produce more power in high compression engines because with poor gas, they require the timing to be retarded a bit from optimum to keep from pinging. With the proper octane fuel for the engine, the ignition may be advanced to an optimum setting which will produce more power. |
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Quoted:
Check with the airport and make sure there isn't any alcohol in the fuel. I'm no expert, and someone should correct me if I'm wrong, but I thought the FAA approved ethanol in the lower grade avgas. Like the 89 octane? The 100LL however is alcohol free IIRC. The FAA does not allow alcohol-containing gasoline to be used in aircraft, even for STC Autogas Certificates (though many pilots ignore the prohibition on their STC). From a typical STC Info-pack: Run the ethanol test on all the gas you buy.
DO NOT burn fuel with ethanol in your airplane. Revert to 100LL if ethanol free gasoline cannot be found. Gasoline blended with ethanol can be corrosive and damaging to aircraft fuel systems. Range is less with ethanol blended gasoline. It has an affinity for water and can pull moisture from inlet air on humid days to an extent which has lead to engine malfunctions. Allowing it to sit for extended periods of time has resulted in the need to replace carburetors, hoses and gaskets. It has also been reported to clean the interior of fuel tanks, leaving the accumulated sludge in the screen. If you cannot find gasoline that you are certain is ethanol free then you must revert to using avgas. It has become increasingly difficult for many pilots in the US to obtain ethanol free gasoline. In some areas of the country it is impossible while in others it is not. This is primarily due to Federal requirements now hard coded into EPA regulations which require ever increasing quantities of ethanol to be blended into the nations gasoline supply. Oil companies are required to do it or they face hefty fines. Pilots must be vigilant when purchasing fuel to make certain that it is conventional, non ethanol gasoline. Be certain, before ordering an STC, that you are able to purchase conventional, non-ethanol gasoline. |
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The generator is out back putt-putting away smoothly on the ethanol contaminated gas I put in just before Field Day. I'll head over to the airport in the morning and pick up a can of real gas, add the Stabil and hope for the best.
I've been recommended to NOT use "Seafoam" additive. |
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Around here most Farm Milking Parlors have GenSets - often either big diesels or more interestingly dual-fuel units (LP or Natural Gas, and Gasoline).
Occasionally you can get one of these sets on the cheap when they upsize. Adding dual-fuel is an option on a lot of gensets. We've gone to using Hawker Odyssey batteries for electrical start gensets that are only occasionally run. The on-demand remote start options are worth checking into as well, as they greatly improve fuel use discipline. The Stabil and PRI-G are the usual recommended storage stabilizers. 73 Steve K9ZW BLOG: With Varying Frequency - Amateur Radio Ponderings |
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Quoted:
During any extended emergency, Avgas is going to be scarcer than unicorn dung. Seems like the best solution would be to modify your generator so that it is happy running on the crappiest grade of Quickie-Mart gasoline you might expect to find after TSHTF. I agree... but good non-ethanol fuel would be better for long term storage, just 5 or 10 gallons with fuel stabilizer. THEN if the generator is going to be run for a week or more of power outage, running it with ethanol pump gas, yes, you should make sure your generator can run from that, too. This is what our Honda service place did, increase jet size to allow the engine to run that crap. I just ran the generator dry, 3-4 hours on the same gas that ran badly on Field Day. It was as smooth as ever. No problems. I did not even have to choke it to start. Just bumped the key and it was running. I'll get the Avgas in the morning, dump in the Stabil. |
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Back from the airport.
5 gal of Avgas. I had already poured Stabil in the gas can, but both the guy that pumped the gas from the truck, and the guy that rung up the sale said their Avgas is very stable, that Stabil or other stabilizers was unnecessary. He remarked that they had some planes that had sat up 5 years and cranked right up and ran smoothly. |