I have a WeedEater gas-powered trimmer. It has a plastic bulb that you squeeze in order to prime the engine. One of the problems with this system is that the bulb tends to crack and fail after exposure to gasoline containing ethanol. That's just another unfortunate result of the move to ethanol.
This story begins when I take a trip to the store to get a new bulb. I get there and find that they cost up to $8 -- for a little piece of plastic!
Alas, in the process of taking off the small plastic retaining ring that attaches the ($8) bulb to the carburetor, I managed to break it. I tried using J-B Weld, Gorilla Glue, and duct tape, but nothing I tried would fix it, so I had to begin the search for a replacement retaining ring. A quick look through the bone yard at the yard equipment repair shop didn't produce anything I could possibly use as a substitute for the retaining ring.
So I looked further for the part itself and found that no such single part is available for this model -- you have to buy a whole new carburetor. Individual parts are not sold separately. Luckily, I found a carburetor for $24, and I was able to put it on myself, saving the $20 minimum that the repair shop charges.
Chalk up another one for ethanol-based fuel. Add to that problem the inability of the WeedEater folks to use the right material in the primer bulb that would be resistant to the corrosion from ethanol. So I had to go through all that trouble to buy what was probably a 25-cent part.
This entry was submitted by A.K. Rosenhan, PE, and edited by Rob Spiegel.
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Dave, the points you make are certainly valid, but the hardware for measuring density is a lot more involved than for measuring resistance. My idea was for the measurement system to be integral with the fuel pickup assembly located in the gas tank, so that an immediate indiaction would be available if the gas being purchased contained water and alcohol. That would allow me to stop and avoid filling the tank with the poor quality fuel. Also, the response could be quite fast.
Are you sure that the separation threshold is only 6% water? I thought that it was about equal to the percentage of alcohol?
@William K.: Actually, I was way off with the 6% number. At 70°F, phase separation occurs when the moisture content exceeds about 0.5%. This document will tell you more than you ever wanted to know about phase separation.
Real-time, in-line measurement of moisture content in gasoline might require infrared spectroscopy, which probably wouldn't be cheap. Maybe there is a cheaper way to do this, but I can't think of one.
Something is missing in the explanation about moisture separateion. Like, what concentration of alcohol are they referencing the moisture separating at 0.5% concentration. Certainly the amount of water that can be disolved depends a whole lot on the amount of alcohol in the mix. That is sort of intuitive.
Of course, that is only with nice grain alcohol, it does not include the less pure stuff, nor is that including the methyl alcohols.
And now ifrared spectometry can be donefast and cheap if only one target is sought, and that target is well understood. BUt I was thinking of something fast and cheap and simple. So the short answer becomes "probably not".
Two relevant things to this issue. 1. There are so many things put in gasoline these days between alcohol and the entire hydrocarbon spectrum, its almost impossible to figure what might have caused early degradation of the primer bubble. If you get five years out of a $60 weedeater, it owes you nothing. Mine seems to take the worst from UV if I don't put it away and out of the sun. Electric weedeaters are toys good for toy-size yards.
2. Parts. B. S. supposed that a weedeater engine doesn't change or evolve. I challenge her to explore the parts breakdowns at sears or repairclinic.com and revise her worldly view of small engine repair. I counted five iterations of a primer bulb for weedeater carbs in one search iteration. Almost all Briggs & Strattons have slightly different production runs. Some common. Some not.
Nothing lasts forever. Having mega stores contributes to the convenience of cheap stuff. Stop whining about the government. If we didn't have gas, we'd all be busy herding sheep or on our knees from exhaustion of using manual mowers. And we wouldn't have all this spare time to spew electronic drivel on how tough life is.
Loadstar, I have a "toy" yard, so I actually use a manual push mower. It is very like my childhood when I earned $$ mowing large yards with push mowers. Given my toy yard, my electric weedeater will last decades. So no complaints here.
Perhaps the best solution is to design multi-fuel. And with all the new advances in batteries coming down the pike, don't forget to keep electric fueled.
I don't buy any ethanol mixed gasoline. It seems to reduce gas mileage and caused deer corn to cost a lot more, plus corn crops are a failure this year. So, I don't expect and price cuts at the pump. My gas powered lawn equipment is going through its first massive drought summer and has operated fine all three times I used it. It advertises that it will operate with ethanol 10% max mix. 10% ethanol in a premium fuel car doesn't work well at all. Fuel in your oil sounds like a different issue like not changing the oil often enough or bad float height or float valve seat. Rarely have I ever had to change a plastic float and if it used a brass float, you usually can still get one made of brass. Maybe not at your local auto parts store, but they are out there.
@William K.: Phase separation occurs at about 0.5% moisture for E10 fuel (i.e. gasoline with 10% ethanol) at 70°F, according to the document I linked to. Like you say, gasoline with higher ethanol contents, such as E15, can tolerate a lot more moisture before phase separation occurs. This is one of the concerns about moving to E15, and one of the reason why longer-chain alcohols such as butanol are being investigated as alternatives.
You can read about some exciting current work on biobutanol in marine applications here.
This is an age old problem, not new. Most small 2 cycle engines have warnings about using gas containing ethanol. The ethanol will disolve not only the rubber priming button but the fuel lines and and the intank gas filter. This can happen using gas with under 10% ethanol. Once you get over 10%, the metal parts can also get attacked by the ethanol.
I have measured the alcohol content of ethanol contaning gasoline by using the well known water test, using a graduated cylinder.
I have also attempted to remove ethanol from gasoline using the same process. It works, but not good enough. The amount of alcohol you can remove seems to vary somewhat with the maker of the gasoline but in any case you cannot get all of it out.
Aside from the direct impact on certain components, alcohol is an effective cleaning agent for tars left behind by gasoline. Use of alcohol in the fuel of an older piece of equipment, even with an engine that withstand it, will flush the accumulated tar out of the system, with disasterous results downstream.
I have not experienced a problem with alcohol in my lawnmower or portable generator, both of which use 4 cycle engines, because I do not use alcohol containing fuel in them. My personal aircraft can not use fuel with ethanol, and it is normal practice to drain a small portion of the fuel from the tanks before flight to ensure that water and dirt is not present. For almost 30 years now I have saved that fuel and burned it in my mowers.
So, if you cannot find fuel without ethanol in you area, you can always go to an airport, and pay maybe $6.00 a gallon for heavily leaded 100LL aviation fuel. Considering how little fuel a mower uses, this is probably far more attractive than buying a new one.
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