Mostly air on my 236

Discussion in 'Fettling Forum' started by Juan, May 31, 2020.

  1. Juan

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    Hello.

    I have some problem with my recently arrived Coleman 236. After a few seconds the fuel seems to be less and mostly is air with a flame you can see on the picture.

    I need some advice on this.

    Thank you.

    Juan 15908799957564597682929486871913.jpg
     
  2. Tony Press

    Tony Press Australia Subscriber

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    Try with less pressure, and see if the flame holds to the burner.

    Saludos

    Tony
     
  3. Norman

    Norman United States Subscriber

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    I agree with Tony because it looks like there is way too much pressure.
     
  4. george

    george United States Subscriber

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    I think so, too. These are a fine lantern and rarely give trouble. Also, you probably already know, they have a fuel/air pickup tube and I think to get correct flame the valve needs to be all the way open. The first 1/4 turn just mixes fuel and air, the full position is just fuel.
     
  5. MYN

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    Sometimes the plunger in the fuel/air pickup tube could be stuck at an intermediate position even when you fully open the valve. The fount air continuously gets picked up with the fuel, just like when only 1/4 turn of the valve knob's been turned. If its so, you'll need to further clean or fix the fuel-air pick up.
     
  6. Anthony

    Anthony Australia Subscriber

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    I have had that happen with a lot of lamps and while reducing the pressure often makes them run more correctly, it is not a fix to the problem.

    Pressure could be the issue and so could what MYN stated above.
    You could also try giving the gause a clean with a soft wire brush.
    Perhaps the air/gas mixture is being restricted.

    I fixed the same problem on one lamp by making sure the jet was shooting up straight rather than on an angle.
    It doesn't take much to have them firing of sideways.

    A couple of easy things to try.

    You did manage to get an interesting pic of that blue flame anyway. :thumbup:
     
  7. Juan

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    Ok, I'll try to lower the pressure but something else is wrong as when turned 1/4 the valve only air comes off.

    Thanks
     
  8. Mackburner

    Mackburner United Kingdom Founder Member Subscriber

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    Sounds to me you are going to have to take the fuel/air tube out and clean it. One trick you might try first is to give the lamp a good shake when it's burning. Doing that will allow some fuel to flow through the air intake and give a short period of a good Bunsen flame. If a shake improves the burn then a fettle of the fuel/air system will likely cure the problem. ::Neil::
     
  9. Juan

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    Lowering the pressure does nothing!!

    I'll give her a good shake. If it would be the case: how to fettle the fuel system?

    Thank you.
     
  10. Juan

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    Ok. So what could it be done here? Let's try to take it apart ...
     
  11. Juan

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    I don't understand what else I can do. Is there anything to do?

    Juan
     
  12. Juan

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    Being everything fine I only conclude that there was little fuel on the tank.
     
  13. Juan

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    A little bit better, but not enough.

    There is a lot of air bubbling on the fuel tube. I guess the rod I too long and even with the valve full open, it still obtures the fuel port and letting the air to push down the fuel.
     
  14. Mackburner

    Mackburner United Kingdom Founder Member Subscriber

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    Looks OK but probably wants a good clean. They can get sticky with old fuel residue. I doubt the rod is too long more likely the spring has weakened and is not pulling it back far enough.::Neil::
     
  15. Alex Smith

    Alex Smith United Kingdom Subscriber

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    @Juan It sounds like the fuel pickup is still blocked. Have you tried soaking the fuel pick up in citric acid? This may clear it.
     
  16. Juan

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    The whole thing is very clean and the spring is very strong. It makes no sense: when the rod is off from the hole the pressure should be the same, inside and outside of the pipe as the liquid level as well. I don't understand why the air still flows through the air hole.
    Let's take it apart again ...
     
  17. MikeO

    MikeO Subscriber

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    With the amount of rust flakes in the fount, I would suggest the following:

    Remove the valve assembly, and we'll get to that in a bit. Put some sheet metal screws in the fount and if you have some strong basic solution like oven cleaner, or better yet lye (sodium hydroxide crystals diluted in water but still strong) put that in the fount. Caution--this is highly corrosive and will burn your skin--rubber gloves and safety goggles or face shield mandatory! Put the fuel cap on and block the hole the fuel valve came out of. Then shake it vigorously. When you figure you've done it enough, do it some more. The sheet metals screws will bounce around removing any loose rust flakes. The basic solution will remove any remaining old fuel varnish and other organic gunk. Dump it out and see what you get! Then rinse clean with some Coleman fuel or alcohol. This should have your fount scrupulously clean. With a fount as rusty as yours, those little chunks of rust will cause nothing but Coleman anguish.

    Now the fuel assembly--disassemble as you did, and then stretch the spring a bit--they do get compressed over time. Take the steel wire rod and run it through some steel wool to get off rust and gunk. Soak the outer tube assembly in some lye solution, rinse, soak in some alcohol to remove any old fuel varnish. Poke the steel rod through the hole to make sure it's clear of gunk.

    Reassemble, and then turn the fuel valve wheel in and out to make sure the rod is moving into the hole and out properly. Reassemble, fill fount with some fuel, pressurize, and open the fuel valve to flush out any residual gunk, and then showtime!

    With a fount that was as rusty as yours, it really helps to keep flushing to make sure everything is unobstructed. The reward is 500 cp of retina scorching!

    Mike.
     
  18. MYN

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    Stole some illustrations of the fuel-air tube principle of operation. Here's the diagramatic view of the generic part to assist fault-finding. Hope it helps:-
    43820984734_3b829cf3f9_b.jpg 44538848521_31d3e206ba_b.jpg
     
  19. Juan

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    Yes, I'll clean everything better because perhaps the restriction comes from the rust on the tank.

    Thank you for the drawing, I was looking yesterday on internet for something like this and I couldn't find any, so I made my own scheme to understand how it works, not as nice as this one ...
     
  20. MYN

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    Just for your interest, a 236 has pretty much the same design as the earlier 242, except that its larger. Attached is the patent of the 242(I believe). The fuel-air pick-up diagram could be seen on Fig.5. in the patent as well:-
     

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  21. peterthevet

    peterthevet Subscriber

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    Very unusual fuel/air tube on that 236. I realise that it is an early production 236 (so may have been design changes) but it is different to the ones that I have examined.
     
  22. Juan

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    Thank you, Myn. The feds tube on the patent is like mine.
     
  23. Juan

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    I tried many things. I cleaned everything perfect, I eliminated the rod en cool, I limited the size of the air port and nothing, it continued to send air through the fuel tube. I finally closed completely the air port with a tape and the bubbling air disappeared but it makes no sense.
    Anyway, the light I had was not good, brilliant but not more than a 200 Coleman.

    I'll take some vacation from this lamp.
     
  24. MarkC

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    Sounds like a crack or split on the inner pipe or pipe-in-pipe connection. I had a lot of struggle with a similar intermittent fault on a Kayen heater. It turned out to be a hole in the fuel pickup, so only occurred when the tank got to a certain level.
    Took a while to figure out as I only used it now and again, putting it to one side and draining it when it stopped working.
     
  25. MarkC

    MarkC Subscriber

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    I suspect you have a crack or leak here
     
  26. MYN

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    There's quite a number of points that could leak or introduce air into the fuel path. For example, what Alex pointed out.
    There're also many other things that you could still try out besides what you've done.
    I'm not quite sure about what you meant by limiting the air port. Was it the tiny air hole in the fuel-air pickup tube or the two main air inlet ports?
    You might what to remove the burner and frame cage assembly to re-asses the problem. For a clear idea of what's going on, you first remove the jet, lower the pricker, pump up the fount with fuel in it and then open the main valve as usual. Within about 1/4 turn of the knob, both air and fuel would be seen from the outlet of the vaporizer with the jet removed (the presence of air bubbles in addition to the fuel). As you open up the valve further till maximum, only the fuel should be seen from the vaporizer outlet.
    If you don't get what's described above, and still getting air bubbles-fuel mix after a few turns of the valve knob, then you're sure the problem's within the fount and fuel-air pickup and not elsewhere.
    I'll assume that all the threaded joints of the fuel-air pickup is sound and not leaking anything in between.
    Next, if the leak problem is confirmed as above, you'd need to remove the valve block from the fount again. Check the protrusion of the fuel control rod from the hole at the bottom end of the fuel pickup tube. Turn the valve knob from close, 1/4 turn and full open when observing the protrusion of fuel control rod. It should retract back into the hole at the bottom of the fuel pickup tube as illustrated in the diagram I posted earlier. If it doesn't retract fully when the valve knob has be turn way pass the 1/4 turn, then you'll continue to get air being mixed in the fuel even when the valve's fully opened.
    Let us know if this is the case or otherwise.
     
  27. Juan

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    Hi,

    @MYN, I did in a different way the tests you mention, but it still flows air from the tank through the air/fuel tube and only when I totally close the air port the air flow ends and I couldn't understand why because it was against of phisics ... I guess the answe is the one suggested by @MarkC , otherwise there is no explanation.

    Thanks, I'll see what I can do.

    Juan
     
  28. Juan

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    until the fuel level is below the hole/crack. It makes sense.
     
  29. MYN

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    Hope you get it sorted out, Juan.
    You should check the inner tube of the fuel pick up first as mentioned by MarkC. If there's a crack or a tiny hole by corrosion, air would short-circuit into the inner tube.
    Also check if the protrusion of the fuel control rod from the orifice at the bottom of the fuel pickup. That's rather critical as it controls both the amount of air and fuel as you turn the valve. It needs to clear the bottom orifice as ilĺustrated when you open pass 1/4 turn of the valve. Otherwise the fuel inlet would be partially blocked and there wouldn't be sufficient incoming fuel to override the air flow.
    Good luck.
     
  30. Juan

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    I checked this first and works fine. There is no restriction when the valve y full open.
     

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