My recently acquired 99 fires up after two rounds of priming, but very weakly. One possibility (or so I'm guessing) is that a poor seal on the filler cap is preventing it from building up much in the way of pressure. Or could the weak flame be a symptom of the wick being scorched or otherwise not up to snuff? I will be replacing the cap gasket in any case, but wondering how likely that is to be the source of the problem. One other thing that has me a bit puzzled is the amount of rotation, or lack of it, in the control valve. The full operating range--from the fully clockwise "off" position to the fully counterclockwise position, with the cleaning needle visibly protruding from the jet--is less than a half-turn of the key. I'd estimate that the total range is 150 degrees or so. I would have expected it to be similar to the range of motion I'm familiar with from my Svea 123, which is around two full turns, I think. Or is this normal for a 99? This is the first one I've encountered. Given that everyone here already knows what a 99 looks like, I'm not attaching a photo for now. But if that would somehow be useful, let me know and I would be happy to do so.
Easy to check pressure loss from the cap. Empty fuel. Place stove in freezer with cap loose. Leave for 10 or 15 minutes. Remove from freezer, tighten cap very good. Dunk tank in hot water so as you can see if cap leaks. Easy. Duane
First suspect is filler cap seal, second suspect is the seal in the safety release valve(SRV) in the filler cap - both seals are easy to replace and easy to make from fuel resitant rubber sheet if needed. There are no other obvious suspects for that problem.
Simple problems have simple solutions, suggesting that this may not be a simple problem. Tried the stove again with a cap from my Svea 123, which is known to hold pressure, and got the same result: Double priming yields a very weak flame. Not sure where to go from here. I know, I should do a dunk test but I am evidently too lazy. What would that tell me that switching caps did not?
Ok - I didn't really think about valve/needle as a possible problem, but one possible issue is wrong needle or needle position - I don't know about the burners on 123R/8R/99 but other burners of similar valve design usually operates with 180+ degrees from closed to full pricking, using first 1/4-1/3 turn for regulating before the needle enter the jet. You could take off the burner bell, warm the tank slightly to get some pressure and(outdoors in safe area) open the valve to check the fuel stream visually. I guess you need to lower the needle one step - close valve, unscrew jet, slowly open valve with slight push on needle until you feel the click, close valve and fit jet+bell - check that the valve close fully first cold, then hot and then after several minutes at full power - too low needle would stop valve before it close fully, most leak with hot burner.
If the gasket in the 123 cap is already a bit hardened, it could be shaped or deformed by the 123 filling neck. Then it is able to hold pressure on the 123, but might leak on the 99. Be sure, that the rubber is still soft to form a good seal. Dunk test recommended, just to ensure a proper seal. Leaking or hardened rubber seals can be very subtle.
If the cap seals are good, remove the cleaning needle rack and try lighting again. While it's out check for carbon buildup. To reset the rack they have to be set to about 4 or 5 clicks. With the regulator key/knob turned fully to the closed position, place the needle on to the cogs and slighty push down on the needle i use a pencil with a eraser on the end,and slightly turn the key to the open position to you hear it click down on 4 or 5 cogs,sometimes 6 is needed. If you look in the instructions gallery there is instructions on this prcedure
When doing the dunk test, open the regulator to check that there are no blockage. Do the same dunk test with your Svea 123 to compare.
I'm fairly new here, and don't know my way around the site very well. What is this "instructions gallery?" you mention. I can't find any reference to it. Similarly, I don't know anything about the cleaning needle rack. I understand that it must be the mechanism that controls the cleaning needle, bit it's a black box to me. I'm a little hesitant to dismantle the valve and hope I'll be able to puzzle things out once I have it apart.
Useful to know, thanks! Is there any way to search the library for any specific articles on resetting the cleaning needle, other than randomly scrolling around? I get nowhere using the main search box for the site. There's nothing relevant under "reset rack needle optimus," for example. I'm pretty good at actually repairing stuff, but it seems that my information-finding skills are well short of what's needed here.
Short tutorial hope this helps , it is a 123R shown but same method , needle may look a little different in the 99 .
Great, thank you, that looks promising--I will have a look. For what it's worth, a dunk test with the original cap revealed no leakage.
Many thanks to all who responded with information on resetting the cleaning needle. After the reset, it burns pretty well and doesn't leak fuel when the valve is turned all the way off. The valve now rotates a bit more than 180 degrees, as compared to 150 or so before the reset. Its full burn does seem a bit short of the full-throated roar of my Svea. Or so it seems, at least--I will have to run them side by side for a more accurate comparison. Also, as is evident in the attached photo, there's some yellow flame in one quadrant of the burner. I haven't delved into the cause of that yet. Note also that I temporarily removed the guts of the stove from the aluminum housing to give everything a thorough cleaning. Thanks again! I love this forum.
Good idea, thanks. It's actually possible to run the stove without the needle, yes? In that case I suppose one could just use the removed needle as an external pricker.
No sign of leak during dunk test Possibly debris, although the fuel flow seemed strong with jet and needle removed. Needle is down five clicks, but possibly still a bit too high? I'll fire it up without the needle and report back.
