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Let’s Talk Fuel Lines!

Discussion in 'Giant Scale News' started by GSNadmin, Apr 7, 2017.

  1. GSNadmin

    GSNadmin Staff Member

    On all of my nitro and gasoline-powered airplanes, I use zip ties to secure my fuel lines going from the fuel tank to both the carburetor and the muffler. When routing lines within your airplane, make sure that they can move freely and are not bent in any odd fashion. After all, you need to make sure that fuel can move slightly from the tank to the carburetor, and also, from the vent line in the tank to the vent on the exterior of the model. However, make sure that these lines do not come into contact with any hot item like the engine’s muffler. Rather, fasten a line if you think it may touch the muffler.

    Also, if you are flying a gasoline-powered airplane, make sure that you change all fuel lines yearly. In the past, I have put airplanes aside for a year or so, but I always perform a pre-flight check on my airframes before taking them to the flying field.

    In this routine check, I go over the fuel lines. On occasion, I have found that gasoline lines harden, and in fact, the clunk line can harden. I have heard horror stories where people have experienced an engine failure while the airplane was inverted and they lost that particular model. The cause- A hardened clunk line that did not fall freely within the tank. As a result, fuel could not reach the clunk and the airplane’s engine quit at a rather unexpected time. Simply said, make sure this doesn’t happen to you!

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  2. Troll

    Troll New to GSN!

    For about 7 to 10 bucks a foot there is a black fuel line by TYGON called FLORAN 5500, look it up... Literally you can forget about fuel line hardening for over a decade! Its been tested for 6 years now by myself with zero degradation and is still flexible like day one (on the fuel pickup!) They claim its 12 year extreme service tubing. Very promising service life since its designed for liquids much worse than gasoline. Got a bird you don't want to play the fuel system game with anymore??? Do yourself the favor and try it. You'll love all but the cost, I promise.
  3. Intrigued...and if it lasts that long than it is far less expensive than traditional fuel line in the long run since we normally have to replace our fuel tubing every year!
    stangflyer likes this.
  4. AKNick

    AKNick 150cc

    I did some research on this a while back. One guy (Jharkin) dug up most of this on the other site. Every tubing has it's purpose. whether it's heat resistant, flexible, fuel/ethanol resilience.

    Viton = (thick wall and black unless it's the Sullivan Pro-Flex version of the stuff which is tan) best for inside the tank. It's expensive, but will last forever. PSP sells the right stuff in a thicker wall, wont kink as easy.

    Tygon = commonly found, cheap, and overtime gasoline will make it harden... change it every couple years

    Tygothane/Polyurethane - good alternative to tygon, lasts longer. TDRC sells this stuff in blue and red. helps to soften the tubing with heat prior to putting over a barb, and it is hard to remove... very hard to remove.

    Blue Flurosilicone - ??EasyLFex?? never heard of it.

    Neoprene - softens over time.

    Fluran 5500 - fluorielastomer -40-400F resists oil and fuel. http://www.teastech.ie/wp-content/uploads/2013/09/FT-Fluran-F5500A.pdf
    pretty interesting stuff, never heard of it.

    I've been noticing that people are starting to put their in tank fuel pickup lines through straws or connected to a brass tubing to keep the line from kinking or falling to the front of the tank. Also instead of zip ties, or wire, people are stetching an additional piece of tubing (1/8") over top of the barbed area, keeps a little extra tension for an air tight seal.
    stangflyer, 49dimes, Snoopy1 and 2 others like this.
  5. Luchnia

    Luchnia 70cc twin V2

    Good information. When I switched to Viton years ago, I never looked back. It is fantastic and the only time I did check it, it was as if I just installed it that day. All of the other lines I have used over the years have been mostly a waste of hard earned money.
    stangflyer, Yakman and pawnshopmike like this.

  6. Snoopy1

    Snoopy1 640cc Uber Pimp

    Be very careful with Viton it cost me a plane this spring. There seems to be several kinds or hardness. If you are not using the correct one it will fail, it can not be stretched . I have also been using it for a while but this spring rebuilt a tank with some Viton and it split at the pipe on the clunk well the rest was history . If you are getting the correct type make sure you know from whom and always get it from the same person. Bought new Viton tubing and it looked the same but it was not so got rid of all of it and when I can verify it is the Correct stuff will buy some more.
    pawnshopmike and Luchnia like this.
  7. Luchnia

    Luchnia 70cc twin V2

    Yep, great points. I bought some one time that was not the same as well. It was not pliable and had a hardness about it you could tell was different. I used it for fill lines and in places that did not make a difference.
    pawnshopmike and Snoopy1 like this.
  8. AKNick

    AKNick 150cc

    I looked all over the interwebs and there is a lot of different viton tubes out there. Some have found the correct style from McMaster-Carr, but others and myself go with another reputable source - PSP. The wall thickness is part of the issue.
    Luchnia, pawnshopmike and Snoopy1 like this.
  9. HRRC Flyer

    HRRC Flyer GSN Sponsor Tier 1

    Good information from everyone. . . . :big_yes:
    stangflyer, 49dimes and dhal22 like this.
  10. stangflyer

    stangflyer I like 'em "BIG"!

    I am really glad this got brought up. I had thought I would look at alternative tubing for my setups. But then I got to thinking of two things that keep stopping me. The first being foremost in my mind. I make it a point to check my fuel lines each end of season and then again each beginning of season. So far, I have replaced only the tubing in my SD 260 once in five years. Yet I firmly believe preventative maintenance is a must to keep our planes flying without disaster. So a little time inspecting and replacing it is not a problem to me. It gives me the chance to really look everything over real well as anyone would do with a regular "yearly" on a full scale. So far all the Tygon I have put in my planes still seems to be as plyable as when it was first installed. The second thing that stops me is "if it ain't broke, don't fix it". I too use the stretched fuel ring over the fuel tubing to act as a clamp band on fuel lines. I have used zip ties before but I am really liking the alternative method lately. I do however do something that not a lot of people do in regards to the carb line and klunk. I use the Sullivan Super Klunks.
    They are quite heavy and have been doing an awesome job for me. I know many guys use a brass tube in the carb line to keep the line from falling forward in their tank. But my theory is this: On a down line using higher throttle settings, I would think an engine would starve of fuel if the line stays at the back of the tank. With the Sullivan Super Klunks, they are heavy enough with Tygon fuel line that they will in fact fall forward and constantly keep the line in fuel. And when going back to an upline, the fuel line then goes back to the rear of the tank. Also, with extremely high "G" maneuvers and due to the centrifugal force, an inertial force it pulls the fuel line out to constantly be submerged in fuel. I guess it must be working because I have never had an engine die from fuel starvation. I saw a YouTube video not long ago that debunked the theory of fuel being "sucked" to the back of the tank in a down line. It clearly showed the fuel falling to the front of the tank and the "stiffened" fuel line and clunk being left subject to open air and no fuel. I would think in order for the fuel to be able to overtake gravity, a falling object would have to be moving pretty fast and for a long time to have the fuel become weightless and stay at the rear of the tank.

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