Bad Fuel - how?
 

I've flown for many years, never had a fuel problem ever. This time, it was clearly the fuel. I know the basics, keep fuel out of sunlight to protect nitro, keep moisture out of the fuel as alcohol absorbs moisture fast, and I keep the fuel sealed well. It wasn't that old, due to weather, it sat 2 months almost, and I used 1/2 gallon without issues. Today I went out to fly, and the engine ran horribly, acted like a bad glow plug, when I removed the starter it would die. The engine was running hot too. I tried another plane and exactly the same symptoms. I tried other glow plugs, looked the engine over very well inside and out, nothing disturbing. So I tried a buddies fuel out, and bingo, both engines ran as usual, perfectly. So how did my fuel go bad? I don't flush fuel back in the tank, I don't add oils or use it as a recycler for cleaning. I have experience, and never before saw fresh fuel go bad in 2 months. It was Mach7 fuel. I have two gallons of Cool Power that sat in the garage much longer that I used today and no problems, so what does someone think I'm missing here? This is a good climate here in FL, not too hot, not too cold, the fuel should have been good.

RE: Bad Fuel - how?
 

I had the same thing happen with a gallon of Morgan Coolpower 15%. I had it for about 2 months, 1/2 empty. Was trying to tune a new engine and it was just running like junk. Thought I had gotten a bum engine, so I sent it back. They checked it out and there was nothing wrong with it. In the meantime, i had taken one of my other tried and true engines out the field and it ran like junk too. i put 2 and 2 together and figured out it was the fuel. I dont know what happens. Maybe the bottle just wasnt sealed tightly? Maybe it was a bad mix right from the start and it was ok at first but deteriorated rapidly? Mysteries of RC......

C2K

RE: Bad Fuel - how?
 

At least it wasn't a mystery in the electronics and nothing crashed my plane, although I was dead sticking many times in the air on a gusty day, it only cost me a prop. Thanks. I suppose it's good weed killer now.

RE: Bad Fuel - how?
 

Hi krosypal,

The enemy of glow fuel is humidity. Methanol is extremely hydroscopic (adsorbs moisture) and if your containers arn't sealed perfectly or you mix your home brew on a humid day you are asking for trouble (and very expensive weed killer).

Living in a very humid environment I have learn't ,(the hard way), to keep bottles full by decanting from my large drum of just mixed home brew into one litre fuel bottles with good seals and leve almost no air gap. These are stored in a tin cupboard kept in a cool shady place. In this way I don't ever have a large container partially full with a large air space of humid air. I do my mixing in the evening (cooler) on days that have low humidity. Treated in this way my fuel lasts at least six months when it is time to mix another brew as the previous mix has been used up.

Cheers,

Colin

RE: Bad Fuel - how?
 

Squeeze all the air out of the bottle if you can. Put the stopper back in if you can, too. Some of the newer fuel bottle tops available seal the bottle so no air can get into the bottle. If your still using a can, like Power Master has, you may have a on going problem.

Get the air out and keep it out.

This also seems to get worse with the more nitro in the fuel. 10% fuel seems to last forever, 30% seems to last a week if not sealed properly.

RE: Bad Fuel - how?
 

I just had a bad gallon of fuel, and due to my disbelief that the fuel was bad I may have smoked my YS 120. It was a brand new gallon opened minutes before I put it in the plane.. see my ongoing saga here..

http://www.rcuniverse.com/forum/Bad_...2810049/tm.htm

I believe the fuel was missing at least oil content, because there was very little oil on the wing. Unfortunately I may have tried to hard to get it to run on the bad stuff before realizing it may be the fuel. Now I"m afraid of the repair bill....

RE: Bad Fuel - how?
 

Thanks for the tips, will use them.

RE: Bad Fuel - how?
 

bad fuel doesnt neccesarilly "ruin" engines -at least not that fast. just run poorly. in all likely hood it was low oil content combined with over lean needle that does 'em in. its certainly possible to get a bad batch from mfgr.that would affectb a good # of engines.

RE: Bad Fuel - how?
 

I don't think it is a science. I like KROSYPAL have never had fuel problems and some fuel I have stored after opening far longer than it was sane to do, however if it works use it. If it doesn't you've just been bit.

RE: Bad Fuel - how?
 

Since this episode last month, I've enjoyed good consistent flights ever since, the fuel I grabbed is two years old, sitting in the garage, but it was never opened. These last a while if moisture doesn't get to them. I just made sure to shake it very well, in case separation occurs. Cool Power 10 and 15%, Wildcat, and Morgan is what I've used, the Mach7 wasn't very smooth in my engines. I'm enjoying the Cool Power, really surprised how versatile the fuel is.

RE: Bad Fuel - how?
 

I ran Red Max for about 20 years until they sent me a bad case. No oil. 3 days, 3 planes acted really funny. I couldn't figure it out. On the 3 rd day , I detonated an OS 46 on my little Cap232. Connecting rod, wrist pin , piston, bearings all junk.
I called them up. They said they had had a few other complaints that week. They said it was the same formula they had always used. The only difference was A NEW GUY WAS MIXING IT. Hmmmm. Well, they sent me a new case , but they didn't pay for the engine. Now I run Power Master. It gives about 500 rpm less power , but it runs cooler.

RE: Bad Fuel - how?
 

I suspect fuel left uncapped loses more methanol due to evaporation than it picks up water. Best to keep it capped in any case.

Jim

RE: Bad Fuel - how?
 

Reminds me of my first gallon. Lasted me from 1991 to 1998, used only when I had a plane that was flyable. In '98, I used up the last of it (by then I had two .25 FP's) and bought some more, it was 10% Cool Power.

in 2003, one of my students had a jug of 15%, I forget the brand, but his OS .46 LA would not keep running. We finally tried some of my 10%, and it ran fine. Nobody else could keep their engines running on his new jug of 15%, so he trashed it and we speak now of certain bad jugs of fuel.

No explanation, I just assumed there was a manufacturing problem.

Good luck,
Dave Olson

RE: Bad Fuel - how?
 

I've read posts on making your own fuel, probably for this inconsistency. Using a gallon over 7 years, I guess it's not cost effective! But I fly almost every day and buy 2 gallons a month average. When I went to a speed shop to see what I can get fresh fuel for, then order the oil and nitro, I was shocked at the cost. It's a little less money in the long run, but imagine a 55 gallon batch going bad?????? Sickening to think about.