115 Degrees in Phoenix today (engine stall)

Discussion in '4-Stroke Engines' started by astring, Jul 31, 2008.

  1. astring

    astring Member

    My little Robin Subaru eho35 runs like a champ, but over 112 (44-47 Celsius) degrees and it will stall out when idling. I read others mention this and I am here to confirm it.

  2. Zev0

    Zev0 Member

    Yep, I second the confirmation. Mine does the same thing. My tanaka 2 stroke surges a little but keeps running. I use the tanaka for commuting and it's never quit on me.
    Last edited: Jul 31, 2008
  3. stude13

    stude13 Active Member

    i think your gas is boiling. mitch
  4. Skyliner70cc

    Skyliner70cc Active Member

    Yep, good old vapor lock. Some folks use phenolic spacers between the carb and intake manifold to help reduce some of the heat dissipated to the carb.

    One option: 100LL aviation fuel would also prevent your problem but engine would be slightly harder to start. Avgas has a lower and more uniform vapor pressure than automotive gasoline, which keeps it in the liquid state at high-altitude, preventing vapor lock. One plus on aviation fuel is that it doesn't stink like regular gasoline so spills aren't as problematic.

    I can't vouch for 100 octane (car) racing fuel. I don't think it would solve your problem because it isn't designed to prevent vaporization at high altitudes.
    Last edited: Jul 31, 2008
  5. I had an old ford minivan that vapor locked. I fixed it by wrapping pipe insulation over the gas lines. This actually kept the lines cool by keeping it from the heat. Maybe some type of insulation over the entire carburetor and fuel lines might help. I don't see it hurting anything.
  6. astring

    astring Member

    Not to worry it starts right back up and temps are only going to be 110+ for a week or two.
  7. Happy Valley

    Happy Valley Active Member

    I'd be curious to know if any lubrication variances or precations are needed at those temps?
  8. BoltsMissing

    BoltsMissing Active Member

    I added that teflon chain lube in the fuel/oil mix during our summer.
    Seemed ok, sounded less "metalici". That was 6 or 7 months ago, still going strong. Due for anothr "fix" cos ya only do this on occasions, sort of a "treatment" to line the cylinder with something on a HT btw.

    How much did I add ? ( I am not a purist)
    Well, there was about half a bootle left so I added the lot in half a tank of fuel.

    Large is correct in saying you can insulate the fuel line to keep direct heat away. Some cars have the same prob. when a carby is situated above the exhaust manifold or the fuel line runs close the some part of the exhaust.
  9. az cra-z

    az cra-z Guest

    Come on down to balmy Tucson, it's only 107 here! My R/S does stall out at idle occasionally, but it's not a big deal. Tried fiddling with the idle screw, won't do that again. That thing is touchy! (the manual advises against messing with it, and they're right)
  10. astring

    astring Member

    happened again on the way home from work (111+). just started it again though. man it is really hot lately.
  11. jimraysr

    jimraysr Member

    Cool The Carb?

    I haven't quite gotten my Honda GXH50 on the road and am not sure I will be on the road when it hits 115, BUT

    I would think of cooling the gas , gas line and carb.

    First seems like a good idea to paint my black gas tank white?

    Place asbestos or current Green substitute tubing on the gas line.

    Then consider putting a cloth wrap on the carb, Add a small container of water above it and a valve to open and drip water on the cloth. Personal swamp box for the bike?

    The Honda does have an insulating plate between the block and the carb. so that part is done.

    I don't promise this will work if i hits 122 again like it did in 89, but any or all might solve the problem at 115?

    Grew up in the AC business and always looking to make the summer liveable outside. Have a 24" fan on the carport with 7 mister nozzles around it to allow me to work on the bike at 110 plus.

    Good luck!

  12. Skyliner70cc

    Skyliner70cc Active Member

    I'm not sure if painting the gas tank or insulating the fuel line would help much. The main problem is the carb getting too hot and vaporizing the fuel.

    I suspect a cloth wrapped around the carb which is kept moist would work and be an easy means of avoiding this problem assuming it can reject sufficient heat to prevent fuel boiling.

    PS Stacking multiple plates is often required to prevent fuel lock. Single plates often don't work. Good luck and let us know how it works.

    I'm surprised that no one has tried AV gas. Some airports won't sell to the public but it should be easy to get someone (pilot) to buy some for you or allow you to drain a gallon for a fee from his wing tanks.
  13. JemmaUK

    JemmaUK Guest

    Mine did that the other day - sort of a pick up, die, pick up sort of thing?

    Im wondering if it might be because I have the engine with the carb on top of everything and it was hot that day... was a little worried it was overheating but once it had airflow round it again it perked up.

    btw, took another run out to mersea - was gentle with the bike very little on WOT and still made 26mph average. The real difference is hills..

    There is one on the way to mersea that I would hit at 35mph and by the top I wouldnt be doing more than 20-22mph. I did it this last time and it hit the top at 28 miles an hour and the bike would even accelerate when the grade leveled off a bit. It might be using a little more fuel, but for the change in performance I dont really care, it makes the bike so much more relaxed to ride and sounds so much better :). I've done over 600 miles on that engine now.

    Jemma xx
  14. JemmaUK

    JemmaUK Guest

    NEVER use anything which contains asbestos if you can avoid it. Its a banned substance in the UK. People wont work with it and you cant even pay people to dispose of it because it is that dangerous. It is a very strong carcinogen for a strange reason that is basically to do with the length of its fibres.. they are just too long to be engulfed by the bodies cells... this weirds them out (I dont know the technical stuff behind it all) and you end up with asbestosis - a nasty form of cancer.

    I am suprised people are still selling stuff containing it - I would avoid asbestos at all costs!
  15. jimraysr

    jimraysr Member

    In order to boil any liquid you must heat it and or reduce the pressure. The hotter the fuel from the tank the less temperature "reserve" you have. So I think the color of the tank could make a signifient difference.

    We don't have much control over pressure as most are gravity feed. I doubt that the fuel pump carbs or using a crankcase pressure powered pulse pump would help much.

    Oil added to the fuel should raise it's boiling point. Not sure if enought to help would foul the plug or effect combustion?

  16. Skyliner70cc

    Skyliner70cc Active Member

    If the OP decides to change the color of the fuel tank, I would love a before and after comparison of the fuel temperature taken from the end of the fuel line. I personally feel it won't make enough of a difference to remedy the vapor lock but I could be wrong.
  17. astring

    astring Member

    I do not think I will. It is not a huge problem, it just stalls at red lights, when the light turns green I pull the cord and drive away. I'd say we have about 2 or 3 more weeks of 111 to 115 temps.
  18. jimraysr

    jimraysr Member

    I don't think there is any actual asbestos products marketed. Other products have been developed to replace it. It is still a general reference for certain types of products that used to contain it.

    While many developed problems from asbestos working in the ship yards during WWII, It was used in many products where it was not in a free state and could do no harm, I am not aware of any major projects to replace the thousands of miles of cement asbestos pressure water pipe under city streets.

    Likewise the "hazard waste site" when somebody breaks a mercury switch in a thermostat in a school. We had bottles of it as kids and played with it all the time. Still here! German Subs in WWII used mercury as ballest and every one that was sunk has spilled tons into the ocean. To much of anything will kill you. Even British Ale. )

    So I would suggest insulating the gas line with some type of flame resistant high temperature fiber tubing product.

  19. graucho

    graucho Active Member

    Ancient family secret (Now theyll have to disown me) for a 4 stroke...R/S I use 1 teaspoon SeaFoam and 1 teaspoon isopropyl alchohol per 22 oz tank. The combination, both lubricates and cools the fuel. The highest weve tested it was 103 deg. wtth 80% humidity. (Not Arizona heat. WOW) SeaFoam is found at autoparts stores. Dont use more that this mix ratio of both. (This will also keep your carb whistle clean)

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    Last edited: Aug 6, 2008