Two variations of the MSR yellow pumps, not mine, but I was asked by a stove chum if I'd have a go at fixing them Here's how they arrived with me, the one on the left the more complete but both lacking the non-return valve spring and the teflon disc that's a crucial part of the non-return valve assembly. The one on the right also lacked an air tube and the brass ferrule that goes in it and the little pins to secure the air tube and ferrule to the pump body When I said 'ferrule' above, it's actually a tiny compression fitting 'olive', which MSR must have found convenient to buy in, since it doesn't have to be quite of that form, as I'll show in a minute The teflon disc (absent from both of these pumps) is pressed by a spring (also absent) against that 'O' ring visible in the non-return valve bore (present in both pumps) So, I got to thinking, "does it have to be teflon?". "No, let's make discs out of thin brass sheet" came back the confident reply. A recent purchase, cheap off ebay (less than 20GB pounds if I recall) The tool's a hole punch of course but that anti-slip locating 'pip' on the mandrel creates a rather useful dished shape in the waste discs, which was ideal to locate one end of the spring. A couple of springs were in a spares kit handed to me by my stove chum, which was convenient, but the kit lacked air tube pins or the teflon washers Speaking of air tube pins, I happened to have a batch of tiny iron rivets - engineering jumble stall purchase Next, I assembled the pump with the air tube, olive and pins to make sure my brass disc replacement for a teflon one did the job. It worked fine, so I set about finding a piece of neoprene tube to fit the other pump and fabricated a ferrule. The crucial part of that from an installation perspective is that chamfer, which the protruding ends of the securing pins jam up against, making the assembly secure So, two repaired, fully-functional pumps. 'O' ring seals in both pumps were well past their best (brittle in a couple of instances) and my mate's service kit was raided to make each pump fuel tight under pressure, which I made sure of before trying them out on stoves First off was the pump that came to me more complete than the other, here powering up an MSR XGKII. Aspen 4T fuel in a Sigg 1-litre bottle Next, the other pump connected up to a pre-shaker jet Whisperlite Though already tested to be fuel-tight, you can never be too sure, and I took a good, detailed look at each one during and after the burn to make sure that neither had so much as a misting of fuel. Happy John
I have an old yellow pump that has just started to play up so the tutorial was very useful. I've even got the same hole punches and some brass sheet in the workshop. Looking good for a bit of weekend fettling. Stuart
Glad that was useful Stuart. It's the 6mm punch size that fits. Likely to be obvious to anyone 'handy' like yourself doing it, but the disc needs a very minor bit of dressing with a file before installing, just to take off any burrs left from being punched out. Happy fettling and let us know how you get on! John
So that is a o-ring down inside there. I'll see if I can get them out on a few pumps I need to fix. I messed up one teflon disc, poked a small hole in it trying to use a nail to give the new tubing some rigidity so I could get it all back in and the other is missing the disc, spring and compression fitting. Duane
I am fettling MSR XGK (I think from year 83). The stove is now ok after I changed sparker unit and replaced priming pad. The stove has a yellow pump that is missing an air tube . Luckily the Teflon disk and it's spring are still there . I need to get the air tube to the pump and the 'ferrule'/'olive' to lock air tube into it's position. Does anyone have idea which colour air tube 1983 era stoves had? What is the correct outer diameter (OD) for the air tube? I have a tube that has 6 mm OD and it seems a bit too loose for the pump . Edit: Just for additional information... My kit is like this one: https://classiccampstoves.com/posts/135874 Also there is the aluminum cup that goes over the stove.
As long as the disc or whatever you have is held securely in place and under some pressure by the spring, the pump will work, it acts as a check valve. Just looks better with the short tubing on the end. Duane
Thanks for posting. A rather complex design for holding the pipe in place, lovely repair, well done all round
