Hi all, this is my first time posting and I think I'm putting it in the right place. I picked up an in-box Coleman 425f from the mid 90s yesterday, got it home, fueled it up, and I can get a big bright orange flame from the main burner, but it never settles down to a blue flame. When opening the valve for the 2nd burner, both burners settle down into tiny blue and orange flames that go up and down in intensity, and when I close the left burner, the right one goes back to just a big orange flame. Just not sure what to do, any help would be very appreciated, thank you
How long are you running both burners? Will have a yellowish flame if only using the main burner. Slightly flooded? Duane
Seems like it needs a good clean, start with rinsing out the tank with a small amount of Coleman fuel. Unscrew the generator and clean it up a bit. These stoves are super easy to work on and they last forever with simple maintenance. I have one from the late 1930s that still works it doesn’t even have steel rings on the burners, it’s all cast iron. I would start with that. I’m sure someone more knowledgeable will chime in. oh I should add that it’s a good idea to run the stove for a good amount of time. Get it really hot, get a good burn through it first. If that doesn’t improve the flame then it needs attention.
I ran them for several minutes, maybe 6 or 7. I should also add that the pipe that the generator tube goes into (not sure what it's called) floods and drips fuel into the base of the stove. I've done some testing outside and the generator either shoots fuel out, or it dribbles out, it never sprays, regardless of lighting lever position, like some other posts have suggested it should
I really don't think it needs cleaning, it's all brand new and seems to have been kept in its box all these years. I may still try
When flooded like described, will take 5 to 10 minutes to burn off the excess fuel. A long preheat startup like instructed by the factory should resolve. Will need to add more pressure while doing. The genny goes into the bunsen, that's where the excess fuel pooled then dripped out. Duane
I've been finnicking with it all morning, if both burners are on, I get a pretty good blue flame from both of them, though it's not consistent like others I've seen online, if the auxiliary burner is closed, I only get a big yellow flame on the main burner
Hi Drew, you have a potentially great stove! It just needs a little TLC to recover from a long idle. A similar Coleman 425f was gifted to me this summer, yard sale item that didn't sell. Outer appearance was mint. But hidden inside were many problems related to poor storage. Stuck check valve, gummy leather, sticky fuel/air valve, and a partial tank of spoiled automotive gasoline. The stove runs great now but it needed a lot of basic troubleshooting. Your testing has already ruled out some possible problems. Pump builds pressure = check valve and leather are good. Tank holds pressure = fuel cap and check valve seals are good. Progress!! Next the flame. Yellow flame = fuel mixture too rich. There are 5 possible root causes I know of; 1. Wrong fuel. 1a) If there was anything in the tank when you got it, flush and dry the tank. Don't trust appearance or smell. Use a turkey baster or ketchup bottle and some tubing to suck the tank dry. Rinse and repeat. It's appalling what people pour into these stoves. (If your tank started empty we can rule this out.) 1b) Use only white gas for fuel when troubleshooting. 2. Stuck or gummy fuel/air valve (my guess based on description of spray pattern). Test by preheating generator tube with a propane torch. Get the generator tube hot, then start stove following the instructions printed on lid. Use main burner only. Yellow flames go away = stuck F/A valve (inside tank). Many threads on this forum for fixing a stuck F/A valve. But yellow flames still there = keep troubleshooting. 3. Generator tube and/or tip is blocked. A previous owner dipped my 425f generator in spar urethane or something similar. That was fun to clean out. But now it works great. 4. Obstruction in air plenum / bunsen / burner piping. Take burner assembly apart. Run wires or brushes through everything. Compressed air is not enough. It's amazing what tiny bees and wasps can do. 5. Learning curve on adjusting fuel knob (black knob) for stable burner combustion. Liquid fuel stoves are more sensitive to control setting than gas stoves. Follow instructions printed on lid to the letter. Changing power level requires more time to stabilize than on gas stoves. The generator tube needs time to change the rate of vaporization to the new valve setting or adding / subtracting a burner. Other folks may know more or have their own preferred troubleshooting procedures. This one worked for me. Good luck, and keep troubleshooting!! Your 425f is a camping classic!
Echo that. I'm going to guess @Gasweld 's #4. Spiders and wasps love to take residence in the air tube. You will have to run wire or a narrow bottle brush through to get them out. ....Arch
Fuel dripping.............you are flooding stove. Most instructions will tell you to have a match AT THE BURNER before opening valve. Then leave lever up for a good minute to get generator up to temp. As Duane mentioned, you may want to pump more pressure while it's getting up to temp. Once flooded, it takes a looong time for all the excess fuel and fumes to clean up, and you will have yellow flames. The generator can provide enough fuel to run both burners. When you are just using the main burner, the generator can provide too much fuel for just one. Shut the valve a little bit and you will be golden. Keep us posted!
Thank you so much for such a detailed reply! I've tried a couple things that I describe below, and the main burner gave me a beautiful blue flame, for about 30 seconds, before going back to being a tall yellow flame. I opened the aux burner and both burners were relatively stable and blue, I let them burn for a few minutes and they became less and less stable, before I closed the aux burner and the main burner went back to a tall, unstable yellow flame. I then noticed leaking at the valve end of the generator tube, I probably just didn't tighten it all the way but I thought I'd mention it. 1. The tank was empty when I got it, so we can rule this out 2. I don't have a propane torch, is there another way I can test this? I think this could be the issue 3. I tried poking a thread from a brass wire brush through the tip of the generator rod, there may have been something stuck in there, as i was able to get that brief but perfect blue flame 4. I ran a pipe cleaner through everything, but I tested after doing this and #3, so idk which step made a difference 5. This could definitely be it, I've never used one of these before a couple weeks ago lol Again thanks so much for your help
I think you are nearing success. The blue flame means your stove is capable of running successfully. What remains is to figure out how to stop the stove from flooding (get a big yellow fireball) after achieving a correct blue flame. Please do not use the second burner for now. Adding or subtracting the second burner requires rapid adjustment of the black fuel knob and/or tank pressure. This adds too many complications for learning and troubleshooting. So avoid the second burner until you have confidence with starting, stopping, and running the main burner on high, medium, and simmer flame settings. Cook some hotdogs maybe! Yes, gently tighten the generator tube to stop the leak at the brass valve. It does not need to be "gorilla tight." Double checking a vital detail; is there an instruction sticker on the fold-up stove lid? These instructions are vital for proper stove starting and operation. (Please forgive my question, but I cannot assume the sticker is there without photos.) If your instruction sticker is missing (many fall off or get painted over) see the Reference Gallery for Coleman 325f stoves, or look on Coleman's website to download a 325f Owner's Manual. For the generator preheat test, you can heat the generator tube with fuel. Begin with all valves closed, a cool stove, and the tank and generator mounted in place. Dribble about 1/2 teaspoon of fuel onto the main burner. Light that fuel with a match or grill lighter. Let it burn out. The generator tube is now hot. Light a match and start the stove per Coleman's instructions. When you get a tall yellow fireball (every stove does this occasionally) quickly close the black fuel knob. Let the fire die down a bit. Then gently open valve a small amount, 1/16th turn or so, and watch for changes in the flame. Usually the flame quickly dies down to blue. It might even go out. This is OK. Just relight it with a match. You will learn how to respond faster with the black knob. You will also learn when to pump more air, and how tank pressure affects burner stability. You will need more pumps of air during a startup than most beginners realize. This is not a simple propane stove! It is a bit like riding a bicycle. Much easier to learn in person than explain with words. Finally, while troubleshooting, keep the air control lever (small wire lever on brass valve) in the "up" or "start" position until the stove is running smoothly. You can leave it "up" for longer than the Coleman recommended 2 minutes. You can run with the lever "up" all the time while testing; you just need to pump air very often to maintain tank pressure. If the Coleman fuel/air lever and startup system are new to you, check out the many good explanations found on this site or the Coleman Collectors site. That little brass lever does important and surprising things. Good luck, stay safe, and keep us posted. Photos of first meal cooked too!
I forgot to take a picture of it, but I was able to cook my breakfast on it this morning! It seems to be working just fine now, thanks to all you fine folks. I think it was some tiny obstruction at the end of the generator tube, but I've now got a consistent sound and a consistent flame. Thanks again yall
