Right, but that isn't the situation he's describing. They should throttle down to low - simmer- and back up thru to medium-high on the main burner with a blue flame. He's describing a serious defect, seems to me. When he mentions "medium to low" I think what he means to say is that the stove will not function correctly at anywhere other than full bore.
Erik, Out of all the responses here I'm a bit surprised this has not been brought up yet- Have you checked the quality of the fuel? The problem you're describing sounds like it could be caused by contaminated fuel- be it by water, dirt, alcohol, or something in-between. Doesn't hurt to take a peep inside the tank and make sure it's clean inside also. If you haven't yet, I'd suggest trying some fresh fuel from a different source from what's in it now.
There's some question as to the description of the symptoms that needs to be cleared up, but he hasn't logged in for a week.
Hello all! I was reading this question very carefully because it's exactly what I'm experiencing. Unfortunately, the conversation has stopped, but hopefully someone will be kind enough to offer some input: I have a 424 that we're currently using on a trip through Africa (almost daily for the past five months). It's not even two years old, and we keep it clean (mainly on the outside, burners, everything reachable without unscrewing). For a while now, the main burner has been burning yellow. When I open the auxiliary burner, both flames turn a nice blue. When I close it again, the main burner turns yellow. The yellow is the type of large yellow flame that leaves behind large amounts of soot. I was, of course, aware that the gasoline in Africa is of lower quality, but other travelers here haven't had the same experiences. Things I tried: - I unscrewed the burner and washed it vigorously with a dish brush. That seemed to help for a while the first time. But the effect disappeared and the second time there was no difference. - I worked a zip tie through the manifold and tied another zip tie to it, which I wrapped with coarse rope. I managed to pull it through, and some sticky black residue remained on the rope, but not that much. So, it doesn't seem to be blocked. - Afterward, I rinsed the manifold and let it dry. No difference. Does anyone have any ideas on what else I can check? I'm a bit hesitant to open the generator tube because I don't have the right tools with me on my trip. Where does the air/fuel mixing take place? I'm thinking it's in the manifold? Many thanks for your input!
I do have a lot of tools with me but I don’t have a vice for example, which is needed for opening the generator tube I think.
After turning off the auxiliary..... What happens to the main burner flame ..... if you turn the valve towards a lower output? Blue flame?
After closing the aux, with the main burner at max output, the flame turns yellow, lets say 75% yellow with some blue right at the burner. When I turn the valve halfway the flame gets even more yellow, 100%. Anything under halfway will get me the same 75% yellow flame (but a bit smaller of course). I think the middle position always had a slightly more yellow flame, but now it’s 100%.
You say 5 months of daily use with gasoline and it just recently starting burning yellow. Gasoline works but it will leave deposits in the generator which will cause issues eventually. I'd guess the generator is certainly in need of a cleaning or replacement. I do not think you necessarily need a vice to get it a part (it's been a while but I've taken a few a part with a couple wrenches, some were easier than others).
After your answer... thank you... I agree with itchy. While burning hot, generator HOT, open all the way, I tap the generator and watch sparks in the flame. Crap dislodges and flows through. See if that helps a bit.
A vise would almost certainly be ad-vised for removal of the entire fuel assembly from the tank, but the generator should respond favorably with just a couple wrenches. Coleman recommended turning the “Down to Run” lever back to “Up” for a minute or so just prior to shutdown, to help burn off carbon or tar accumulations in the generator. This is probably more important when running gasoline than pure Naptha e.g. Coleman fuel. With all that said, I doubt that (generator) is the problem, although gasoline formulations vary widely. Maybe. I’ve been running gasoline for quite some time through a 425D, many gallons, without issue. I expect that the generator will become obstructed eventually. Once in a while I’ll have to rotate the fuel control back and forth, to clear the orifice. It has a “tip cleaner” of sorts, just like the lanterns. If you run anything other than Coleman fuel, you will see the utility.
Thanks all for your time and help! Just openend the generator tube. Lots of carbon in there. Cleaned the rod that ends with the needle. So far I wasn’t able to get the spring out of the tube so it’s boiling in some vinegar now. If the spring and inside of the tube have the same layer of carbon, which I’m pretty sure about since it doesn’t come out, I’m certain that this will improve the flame. Will update later. See below a picture of how the rod came out before cleaning.
How high is the humidity where you are at, generally? A fair amount of moisture can be introduced into the fount via the pump over an extended time period. Coleman suggested emptying and rinsing out the tank with clean, fresh fuel periodically.
@Doc Mark used 20 year old fuel in a 425 with no bad results. Of course Coleman wants you to buy new fuel.
Well sure, but this fellow is somewhere in Africa, running automotive gasoline for five months straight.
Sometimes up to 90% but also around 25% depending on the location. I emptied the tank an nothing specials came out. Good to take into account though.
Update: I finally managed to get the spiral out of the tube by heating the tube on another’s stove en tapping the tube to loosen the soot. Used some steel wool to clean the inside but there’s not much left. Will try to find some carb cleaner around here to flush everything. See how that goes. Will update later when I have a flame again!
Ok it has been a while since my previous message. I cleaned the tube and spiral with vinegar and baking soda and by adding heat. Looked pretty clean (already not too bad when the spiral came out actually). After putting everything together the flame was still yellow. Started focussing again on the U-tube. There was still some sticky soot there but very difficult for me to reach since these flexibel brushes are not widely available here. After a while I finally found some carb cleaner, which I used to clean the inside of the U-tube. Also mixed some with the fuel in the tank. I have the feeling it’s now slowly but steadily cleaning the inside of the U-tube. Flame looks a bit more blue but it seems to be taking a while. Hopefully I will get there soon. Again, once I have blue flame again I’ll post it here. And I’ll continue my search for a brush to speed up the cleaning inside the U-tube. Have a great weekend and thanks for your help!
Without reading all the posts, I suspect you are flooding stove a bit. Have you run this thing for a good 15 minutes to clean it out? And to avoid flooding to begin with. most Coleman instructions will ask you to have a match AT THE BURNER before opening valve, if you open valve then fiddle with match/lighter for a few seconds your stove is already a bit flooded. Let us know how it goes!
Thanks for your reply. I ran it several times after cleaning, also for longer than 15 minutes. And also before cleaning we always run it longer than 15 minutes. Sometimes up to 1.5 hours. But I think there is still leftover residue in the U-tube. I agree that this is probably due to flooding. Normally we have the flame ready but it usually takes like 5-10 seconds after opening the valve for the gas to reach the burner, after which the flame starts. This goes quicker if we open the valve even more but this is also the cause of creating some more sticky residu/flooding I think. I hope running the fuel/carb cleaner mix for some time over the coming days will eventually clean out all the remaining black sticky residue.
