Hi everyone, I've been working on a Coleman 550 B stove. Troubleshooting was a bit annoying, as one defect was compensating another. It looked like it was a running on a nearly empty tank. Only fumes and air passing through. When shook, it picked up fuel and was burning on for several seconds. But the tank was full. Problem was the outer tube (I don't know, if there is an official part name for that) of the fuel pick up was clogged at the bottom and had a small crack at the top. So it only picked up fumes and no gas. Now about repairing it: First option would be to remove the outer cracked tube. So the inner tube will pick up fuel at the bottom. Risks I'm thinking about: the diameter of the inner tube is not restricted anymore. This could lead to increase of power or irregular combustion. On the other hand, small particles might get picked up and clog the valve/generator. I'm okay with both. But I'm quite unsure if the outer tube serves another purpose: Maybe some kind of protection against the flame burning through the generator and back into the tank. This could only happen, if you're running on fumes and low/no pressure. That's what I would like to avoid. I guess Coleman wouldn't implement this part, if it wasn't necessary. Second option would be to solder the crack. But I'm unsure if this will work out, as it needs to be airtight. Any opinions to this? Or anybody experienced this before? Attached are some images. Thank you very much, Jake
I believe you change the startup procedure, just guessing. Would need to use a torch to preheat the generator quite a bit or likely the stove would never settle down to a blue flame. Duane
The outer tube only carries air from the top of the tank to the pickup inlet for atomization for instant lighting. The early models came with an entire separate valve, generator, and fuel pickup assembly for kerosene/paraffin with no outer tube or pickup orifice fuel restrictor rod/wire. If memory serves, this kero assembly fuel pickup tube was slightly longer than the inner tube on gasoline assembly since the fuel pickup didn't have the additional effective length of the outer tube's pickup orifice. But don't quote me on that. Next time I'm at the shop, I'll dig one out and measure it. You can delete the outer tube, no problem, but you will want to preheat as Duane said. Turning the valve on will instantly flood the generator if you don't. The unrestricted fuel pickup is not a flow issue. Fuel flow to the stove is solely regulated by the gas tip diameter and the cleaning/regulating wire at the far end of the generator. If you don't extend the pickup tube, you won't get as much run as you will have fuel in the tank that the pickup can no longer reach without the outer tube. But the bonus is, you won't have to add additional air NEARLY as much. Hobby stores carry brass tubing that you can use to solder an extension on fairly easily. Or you can just live with with that "maybe 1/8 inch" of unusable fuel. I don't have access to my parts right now, so I can't give you an accurate measurement. There won't be any additional safety concerns. Flames cannot travel back into the generator, through the valve, down the pickup tube into the tank. One of my favorite features of this stove is how fast it is ready to cook after lighting with gasoline/white gas. Deleting the outer tube will no longer allow for instant lighting. All that said, where is the crack and how bad is it. That tube is designed to leak air at the top. It may not be an issue at all. But it shouldn't be difficult to repair if you know how to solder.
Duane is spot on, BTW I initially had this at the top of my post and accidentally didn't copy the top line when I was editing it. When I pasted it back, I didn't catch it. When I did, it was too late to re-edit. My apologies.
Thanks for the advice, Duane and Mike! I forgot to update the post, but I gathered some more experience over the last few weeks. Well failures tbh, but I gained some knowledge nevertheless. First I soldered the crack on the outer tube shut. I reassembled everything, lit the stove but the problem stayed the same: only running on fumes and I needed to shake the stove to keep it running. So I disassembled everything again and soldered the outer tube airtight to the inner tube, at the top where the pressure fit is (not knowing what I was doing ). While trying to start the stove, there was liquid fuel in the burner. It burned for quite a while with a sooty yellow flame. Later the flame turned blue but there was a significant power decrease. That's where I guessed, the small opening might be intentional. I did some research, read the Coleman Insta-Light Patent (US1718473A - Oil-burning device - Google Patents) and understood my mistake. But it is a very interesting and clever solution to cold starting stoves and lamps. Regarding my stove: I will try to remove the outer tube again and clean up the solder. But I don't have any hope, the stove will properly run ever again. It's a very fine equilibrium between the opening for the air and the hole at the bottom of the outer tube for liquid gas. I guess I will sell it as defective. Thank you guys for helping out!
You could shop for a replacement part. Web search found this source in Spain. The seller's valve looks like the plastic version of the fuel/air tube, not brass. Coleman Replacement Valve 201272 The Coleman 550B was a NATO stock item for many years. You might find parts easier in Europe than North America.
