Gas tank Foaming
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Gas tank Foaming
Hey Guys, I've looked thru lots of your pics of your setups on the large profiles with gas engines and I'm having a problem I hope you have a cure for. I'm running the mvvs 2.15 gas on an 80 edge and I'm having trouble with gas foaming which leads to the engine quitting. The prop is balanced and at idle I have no problems but as soon as I rev the engine up, the tank looks like the inside of a washing machine. I have the tank zip tied on with two ties and I have one layer of foam between the tank and fuse. Could it be that I need more foam and/or to loosen the ties? Ideas??? thoughts???
thanks
Bob
thanks
Bob
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RE: Gas tank Foaming
Hmm, that really sounds odd. Gas doesn't foam as much as the glow fuel and we generally don't even use the foam on the giant gassers. Are you using some kind of funky pump gas? like CA gas with all them additives!
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RE: Gas tank Foaming
In West Virginia, hardly LOL I'm obvioulsy getting vibration thats going straight to the gas tank. Am I the only one thats ever experienced this? I bought the MVVS used but it doesn't seem to shake any worse than my g-62. I don't know if moving the tank further back on the fuse would help?
Bob
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RE: Gas tank Foaming
Moving the tank won't give you any appreciable difference. An old trick used in glow fuel was to put a few drops of Armour All in the fuel. Never tried that but supposingly it cut down the foaming very well. You just may have to add more foam or change the type of foam you use to something more or less dense.
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RE: Gas tank Foaming
Well I ended up moving the tank back to the cg on the wing saddle and it seems to have helped cure the problem. If the weathers good this weekend I'll fly it and see if I can get by without any dead sticks.
Bob
Bob
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RE: Gas tank Foaming
Well I thought I had it cured but I'm still having problems. I'm beginning to wonder if I need to take a dial indicator to the motor. I can feel the vibration when touching the fuse but it seems so slight I can't believe its causing the tank to shake as much as it does. I got some softer, thicker foam and I'm gonna put it under the tank and use rubber bands instead of the tie strips. As long as I don't run the tank very empty it doesn't really matter but once I get low on fuel it sucks air and thats the end of the flight. Leave it to me to run into a wierd problem. But man I do love this plane. The guys at the field love the way it flies and lands. Count me as a satisfied OMP customer.
Bob
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RE: Gas tank Foaming
well I hope you get it solved Bob. I know how frustrating engine problems can be. Ask around your club and field for the local engine expert. Might be something like ignition timing being off?
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RE: Gas tank Foaming
Sounds like your clunk is too light on too long a fuel tube and it bounces with vibration. Put a heaver clunk or put a piece of metal tubing halfway down your clunk tubing so that it won't bounce as much.
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RE: Gas tank Foaming
Also check your prop and spinner balance, I am one of the California guys and I don't have a problem with that. I am flying a 2.15 MVVS on a 80in edge.
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RE: Gas tank Foaming
Gas can and will foam up, sometimes real bad depending on the oil type being used. Any gas two stroke oil containing some castor oil (which is still very popular) can foam up. If you are using a castor based gas two stroke oil, this could be a contributing factor.
If vibration is severe, do not ballance the prop, instead find the heavy blade and mark it. Many times I have reduced engine vibration by putting the heavy blade opposite the piston stroke and then fine tuning the vibration by moving the prop an eighth of a turn around the hub at a time untill the vibration at higher throttle settings is minimized. it takes time but can be very helpful in reducing vibration.
Hope this helps
If vibration is severe, do not ballance the prop, instead find the heavy blade and mark it. Many times I have reduced engine vibration by putting the heavy blade opposite the piston stroke and then fine tuning the vibration by moving the prop an eighth of a turn around the hub at a time untill the vibration at higher throttle settings is minimized. it takes time but can be very helpful in reducing vibration.
Hope this helps