A friend asked me to take a look at his MSR Firefly ... ... which was sprouting flame where it shouldn't, below the burner outer bell/primer cup. See my fingerprints in the soot residue? I stripped the stove down and I'd a yellow pump to add a new air tube to. While I was paying him a visit my stovie chum gifted me the Lytham Tiddler - at the right - and wanting to replace the leaky fabric-covered fuel hose, thought I'd include that as a side-order to the Firefly fettling 'mains' I'd cleaned all the Firefly components for that photo, but backtracking to the sooty-fingered stage, the trouble lay here See that aluminium spacer/pivot for the wire pot-rest/legs? It's too long ... I'll make it more clear in a minute Key to a fuel-tight seal between the aluminium body component and the brass riser is that the chamfer at the base of the riser mates with the chamfered base of the tapped hole in the stove body Back to that aluminium spacer/pivot. I said "it's too long". Here's what I mean. I've screwed the riser home in the aluminium body, leaving a gap between the locknut to the outer burner bell and the head nut (representing how it would be once assembled) ... and there's no space for the spacer. Conversely, when it's in place it prevents the riser from making that mechanical seal with the stove body How it should be, on the left. How it is with the spacer in place, on the right As far as I can make out, there's been no thread locking paste on the joint - there's no need for it if the spacer had been the right length - so the only thing that had prevented fuel seepage was the binding of the threads when the stove had been newly assembled. That's no basis for a fuel-tight joint of course. Working even fractionally loose in use (not even enough to make the joint sloppy) and fuel seepage was inevitable. So, a simple fix. I was able to reduce the length of the spaceer by as much as 1/16th inch and still leave plenty of room for the pot rests/legs to pivot freely Assembled, the riser was now making a proper seal to the stove body, leaving a fractional amount of clearance between the lock-nut to the outer burner bowl and the spacer. In other words, the spacer was no longer preventing the riser from making that tight chamfer-to-chamfer seal at the base of the tapped hole A few Firefly/pump details follow, then it's onto the side-order of 'Lytham Titch' There's a threaded rod with a flat machined on it that takes up most of the space in the central hole in the riser. Prevents the burner being overpowered by a deluge of fuel and flooding I guess, adding to the mass of metal in the riser to maintain vapourisation and thanks to the hexagon socket in it, it can be removed for cleaning, whereas a fine hole running the length of the riser would be a devil to unclog. Figures The control spindle, in aluminium. I cleaned the lumpy grease off it, checked the 'O'-ring seal - which was in fine shape - and re-lubed it with silicon grease before re-installing it The pump was complete except for the air tube, which often harden and disintegrate on these I gather. Luckily, the 'teflon' disc (I'll give it that tag but I'm blowed if I know what it's made of) was still in place. If it hadn't, I'd have replaced it with a brass disc, as here ( MSR Yellow pump(s) repairs) Ok, I'll fire up the Firefly in a minute, but the 'Lytham Titch' side-order. Why feature it here? Well, nothing to say two fettles can't go on side-by-side and the Firefly's chunky components, like that aluminium billet body seemed to stem from a design philosophy not a million miles away from that of the 'Titch', with the brass block stove body at the heart of it Firing up the Firefly. I've got it rigged up with iso-butane here, but more shots follow in a 'reply' [CONTINUED IN A 'REPLY'] John
More shots of the Firefly in action. Barely visible here in daylight I'll grant ... ... but at night rather more obvious, on simmer ... and at full throttle So how'd I get on with the Lytham Titch re-hosing did I hear you say? (or maybe not) John
Great photos and a great fettle John,Thanks. I'm now looking forward to using the Firefly. Will the lid go on the Titch with the new hose added?
Teletim asked Good question! I'd assumed so ... Yes, it does Tim, and thanks again for a much-appreciated gift. Funny how the Titch was made just up the road from us on the Fylde coast at, er, Lytham! Titch and debugged Firefly (latter on iso-butane) Firefly, more lively, on Aspen white gasoline John
Really like the flame pattern on the Titch. Also interesting is how the spacer problem was easily found and solved by you and lost by the folks at MSR. Good save.
Wow - this is really, really excellent. Bravo for an incredibly well-done tutorial! Thanks so much for taking the time and effort to illustrate and explain this so well. Now before I tear apart my Firefly to see if it has this same issue, is there anything or any experience of folks that would indicate this is a common fault, or a one-off, or..?
Theyellowdog asked, I'm sure there wasn't - no abrasion marks left by a metal shim washer or residue from a heat-proof fibre one. Also, of course, there'd been no direct contact between the end of the riser tube and the base of the tapped hole. I'd already looked through the Stove Reference Library for a schematic drawing. There's only an 'external' view and not a cutaway (as I'd expected there wouldn't be) and though user-replaceable parts are identified, there's nothing about a packing washer to go in that cavity. John John
I have been trying to think of another liquid fuel stove where a brass riser threads into alloy (without any other seal). I am sure they exist but I can't think of one. I wonder if the hole is too deep, rather than the shim too long? The same end result. Glad you noticed and fixed the problem. Dan
Those are large holes in the Titch silent burner, am I right in seeing a tea strainer type of mesh inside to prevent underburn?
John, I'm one who has followed this but had very little to add. There are some old crotchety guys who don't care for banter. I like to throw some humor in, I don't smile very good, so my joking around is my smiling. Thank you for all you do. In response to xgkisgod's thread. Duane
Hi John, Thanks for the post. I did a visual check of my FF and didn't find the same problem as you've expertly explained above. It seems to burn quite nicely, so I'll not tear it down, but, I'll know where to turn in case something does develop. Have a good day, sam
I had my user FF out this weekend, checked it out after I made camp. A bit of the threads show above the block, so I'm good to go I believe. Had no issues, it does love a good prime, my whiskers are mostly intact still. I thought it was dying or needed to be pricked, but it was just the adjustment, gave it more throttle, ran fine, sounded like a steam locomotive though. I'll have a report up Monday in the Action Gallery. Duane
