I recently acquired a Coleman 425(?) with 00 stamped in the bottom so I assume a 2000 year model. It was in rough shape. I scrubbed all the rust off and repainted (not finished yet). Took the burners apart, cleaned them and put them back together. Blew out the manifold. Before I did all of that, I fired her up. She had a small leak at the valve, so I put in a new graphite packing. if the burner on the right was the only one burning…. I got yellow flame blowing high and just a couple spots of blue. If I turned on the auxiliary burner.. then perfection. Both burners had a nice blue flame all the way around. And no yellow flame. As I turned down the auxiliary burner the main burner start getting yellow and I lost all blue flame. After the cleaning… the same thing. So I cleaned the generator super good. Same thing. Purchased a new valve (minus generator)… same thing. Bought another tank and put brand new valve in that….same thing. what is going on?!?! Any help would be greatly appreciated!
Yellow flame indicates too much fuel too little air. Try mechanically cleaning the manifold and the bunsen (curved part of right side of manifold where generator goes in). Blowing it out with compressed air or even running water is usually insufficient to dislodge the usual suspects, wasp nests and spider nests. Use a bottle brush, a piece of stranded wire that has been frayed out like tree branches or anything else you can think of to remove obstructions in the manifold. Then look and feel inside for anything blocking the air passages. Fill the tank at least 1/2 full and pump 30-35 times. With the tank off the stove and outside, turn the up-to-light lever up and open the valve 1 turn. You should get a stuttering, misty sort of spray from the end of the generator. Turn the lever down and the spray should turn to a solid stream. if it fails this test, remove the valve and clean the fuel/air tube that sticks down into the tank. If it passes, install the tank making sure the handle on the case does not block the tank from going tight against the case. Turn the up-to-light lever up and light the stove. Leave the lever up until the flame goes mostly blue, then turn the lever down. If it still exhibits the same behavior try more pressure. I have a 413 that acts like that unless I use 40-50 pumps, but it is an anomaly. Report back. Good luck.
Awesome info. I will clean the manifold with a bottle brush. I think the wife just bought one for her coffee thing she takes to work . That new valve (brand new out of the package) came with a new fuel/air tube attached. I worked the lever to make sure it functioned. But I will confirm what you say. As soon as I get this food off of the charcoal grill and eat I will do as you say and post an update. Thanks for the info!
If you think about it, the generator has to produce enough to potentially feed two burners, so if only one is being used it could be running on the rich side. Just turn it down a little and it may be just fine.
I have.. the burner never gets blue. The only time the burner on the right is burning a blue flame all the way around it with no yellow is if the auxiliary is on. just walked into Walmart for a bottle brush… cuz the wife threatened me if I use hers. And I believe her.
Ok….cleaned out the manifold. Same issue. Here are photos depicting what I was saying. The first is the right burner. That’s as low as it goes and still stay lit. The blue is just sort of hovering around the burner. Never comes out of it like it should. Until both sides are lit.
As an onlooker (I don't own a Coleman multi-burner) I have seen fuel/air mixture issues being reported quite a lot. A certain amount is because the stoves are made to run both burners, not just one. When the routine "clean it back to factory state" advice doesn't work, the only successful approach I have seen reported is per below. I'm not saying that adding or removing rings in the burners is the solution, but I am saying it is the only "last ditch" fix I have noted people succeed with. From what has been said, adding a ring pair to the main would be more likely to succeed in your case than removing one. But again, this isn't the voice of experience, just the yammering of an eccentric observer.
Your fuel generator is not hot enough to fully vaporize the fuel with in. Turn down the supply to the single burner a bit and allow the generator to fully heat up. Once it is fully hot it will vaporize all the fuel within, which will result in a ring of blue flame in the single mode and also in the double mode. Just let it get fully hot first before you add more fuel. Call me the resident Coleman fettler. I know these things.
Is obvious that the tip of your generator is not tight enough, thus that "candle flame" Fix that. That lazy look to the flames is flooded. Light it as per directions. Pump it up a lot. Let it get generator hot. All of these will produce yellow flames if just the primary burner is lit, and the valve opened wide, so bear that in mind. One of my fav saying is "fix what is broke" Your generator tip is leaking, start there.
I'm going to have to respectfully disagree with the "designed to run on both burners" notion. A 2 burner stove in good condition will throttle the main burner alone all the way down to just a whisp of a blue flame, fully equal to any home range.
They run great on one burner, or two. Yes, the generator tip needs fixing. Remove, clean threads, and reassemble. Take care not to break the pricker on the rod inside. A good idea to remove and clean the rings. Note the assembly when removing. When reassembling note the surface they sit on is flat, tight fit, and clean to prevent under burn. Pump Lever up Light Get generator hot Lever down Pump, pump, pump When hot, open auxiliary
im having this exact issue with a 425 from 1969. I changed the tank from another 425 (older one) and its blue flames at simmer and burns perfectly. So...I am replacing my generator tube...mine on my bad one was very clogged and bent. Not sure if that helps, but agree with others.. probably the generator tip.
On the 426 stove quoted above that burned okay with just two sets of rings, I next tried a new burner set. I can’t remember if I used the included restricting baffle, but the stove burns fine now with the normal three sets of rings. Curious that a full cleaning of the older set of three rings did not fix the red burning issue for me. Maybe the baffle is the difference.
Ok. So here’s what I’ve done since last night: -cleaned the manifold -swapped a set a set of rings from one side to the other (actually made things worse). however… I did notice that the side on left had like a big thin “washer” on the bottom. The right was missing this. I swapped it over to right side and that seemed to help. Also… I was googling and reading forums while it was burning, maybe 4 minutes or so, and the yellow flame went away. (Took an abnormally long time for the genny to get hot enough to vaporize). So.. I think I will order new rings for both sides and a new generator. I couldn’t tighten the tip anymore without clenching my teeth and grunting really loud. So, new rings and a new generator is in this things future. Thank you all so much for your speedy, insightful help. If I had long arms I shake y’all’s hands!
I remove the tip and thoroughly clean the threads. Being sure to restore the threads to as close to original as possible. That washer at the bottom may also have helped the seal at tha bottom. A little talked about detail.
