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Author Topic: Hey! My fuel went bad!  (Read 1680 times)

Offline frank mccune

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Hey! My fuel went bad!
« on: March 29, 2013, 05:19:58 PM »
    Hi:

    I began to get my airplanes ready to use last week and I noticed that the engins wil hardly run when I disconnect the glow plug.

    I have narrowed it down to the fuel beng bad! I have been told that by adding nitro to the fuel, I can salvage this lot of fuel.  This fuel is supposed to be 10%.  Finding nitro around here is going to be rough. Is there any common thing that I can add to my fuel to get it to run well without the battery being connected?

    Of course I could always use this fuel to clean engines and for break in!

                                                                                                        Tia,

                                                                                                        Franchi
                                                       
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Offline Phil Bare

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Re: Hey! My fuel went bad!
« Reply #1 on: March 29, 2013, 05:26:41 PM »
Frank, fuel goes bad because it absorbs moister from the atmosphere, best thing to do with it is to discard it.     Regards, Phil Bare
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Offline Steve Helmick

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Re: Hey! My fuel went bad!
« Reply #2 on: March 29, 2013, 05:57:36 PM »
Sounds more like a bad glowplug to me, or at least way too cold a heat range. Did you try different glowplugs, and what brand of glowplugs? I won't bother with a Fox plug.

Fuel doesn't go bad like that very often, unless you store it out in the shed, and/or it's not well sealed. I leave my jug of fuel with the mustard pump in it, in the garage all winter, with zero problems. I left some opened and unused for about 5 years, and it still ran fine. Maybe your fuel wasn't good stuff to begin with? Again, there are some brands that I just don't bother with.  H^^ Steve
« Last Edit: March 29, 2013, 08:19:57 PM by Steve Helmick »
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Offline tom hampshire

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Re: Hey! My fuel went bad!
« Reply #3 on: March 29, 2013, 06:03:51 PM »
What Steve said.  If the jug was not sealed and it was stored in a damp space, it may have absorbed moisture.  Try freezing the whole jug and then pouring it through a strainer.  The fuel wont freeze but the water might.   If the strainer comes up with leftover ice pellets, try running it again.  If it still cuts out, try a one tank sample of the fuel, with 1-2% igniter added.  This can be acetone, propylene oxide or lighter fluid.  If that works, then add igniter to the whole jug and use it up.  Go slow on maneuvers until you have a couple of reliable runs.
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Offline C.T. Schaefer

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Re: Hey! My fuel went bad!
« Reply #4 on: March 29, 2013, 08:41:24 PM »
Or...... Try some different fuel to see if that fixes it?
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Offline Jim Kraft

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Re: Hey! My fuel went bad!
« Reply #5 on: March 30, 2013, 09:07:55 AM »
I have been running Sig fuel for years and always had good runs. I had one gallon left over from 5 or 6 years ago that I started flying this year. It ran fine in my Fox 35, but was erratic in my McCoy 40 Red Head. I tried some new fuel and it ran fine. So I guess my McCoy is fuel sensitive. It also does not like anything over 5% nitro as it will burp like a Fox if slightly on the rich side. I have found that straining old fuel through a coffee filter will many times restore it to a usable condition.
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Offline FLOYD CARTER

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Re: Hey! My fuel went bad!
« Reply #6 on: March 31, 2013, 09:49:46 AM »
I have had old fuel that precipitates little white flakes.  I think that is the castor oil.  A couple strainings through coffee filters will restore it.

Floyd
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Offline phil c

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Re: Hey! My fuel went bad!
« Reply #7 on: April 01, 2013, 11:41:48 AM »
Quote from: tom hampshire on March 29, 2013, 06:03:51 PM
What Steve said.  If the jug was not sealed and it was stored in a damp space, it may have absorbed moisture.  Try freezing the whole jug and then pouring it through a strainer.  The fuel wont freeze but the water might. 

Ethanol distills to 95% alchohol and 5% water.  Grain neutral spirits at the liquor store or 180 proof.  Methanol can be distilled to 100%.  But it is nearly totally compatible with water.  If I read the phase diagram right with small percentages of water you'd have to get the temperature down to somthing like -300 degF, where you'd get some separation of small percentages of water  2.5% or so as a liquid.

filtering through paper of some kind is likely to absorb some of the water, along with picking up a significant amoutn of methanol.

Adding some ignition improver would work, but it won't run the same as dry fuel.
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Offline Brian Hampton

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Re: Hey! My fuel went bad!
« Reply #8 on: April 01, 2013, 10:02:43 PM »
I did an experiment years ago by gradually adding water to fuel to find out what affect it had. If the engine started and seemed to run OK then I flew it. This was in an RC plane so if it gave a problem while flying I could land. I got up to 3% water with no change at all in how the engine ran but once I reached 4% the engine wouldn't even fire. The problem was that all the oil in the fuel had come out of solution and was sitting at the bottom of the tank around the clunk. An engine apparently won't run on 100% castor :).

I did some further testing back home using my freezer to cool the fuel and hot water to warm the fuel and found that the colder the fuel the less water it took to drive the oil out. There was virtually a straight line correspondence between temperature and water % for the point where the oil dropped out. Although I didn't do a proper test I'd noticed a large difference between castor and a synthetic with castor being much better at staying in solution. I might add that when the fuel was warmed back to the point of oil dropping out, it instantly remixed with a bit of a shake. This was with a fuel that was 80/20 but, because I don't use nitro, I can't say what affect nitro might have.
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Online Brett Buck

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Re: Hey! My fuel went bad!
« Reply #9 on: April 01, 2013, 11:05:35 PM »
Quote from: tom hampshire on March 29, 2013, 06:03:51 PM
What Steve said.  If the jug was not sealed and it was stored in a damp space, it may have absorbed moisture.  Try freezing the whole jug and then pouring it through a strainer.  The fuel wont freeze but the water might.   If the strainer comes up with leftover ice pellets, try running it again.  If it still cuts out, try a one tank sample of the fuel, with 1-2% igniter added.  This can be acetone, propylene oxide or lighter fluid.  If that works, then add igniter to the whole jug and use it up.  Go slow on maneuvers until you have a couple of reliable runs.

    On the converse,  If you keep light away from it, and keep it sealed, it can last a very long time. I have run 15-year-old fuel at the NATs several times and it worked fine.

    Brett
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Offline bob whitney

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Re: Hey! My fuel went bad!
« Reply #10 on: April 02, 2013, 02:33:05 PM »
the real boat guys have a special filter funnal that wont let water through .,it really works
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