MSR white gas stove pump failure

Jeff,

I have a 25 year old MSR Dragonfly. I upgraded to the newer pump version about 6 years ago but haven't used the stove since 2011. It worked fine and even with a lot of use on the original pump I had no failures.

You did everything right. In fact you should not have had to even do the maintenance you did but having a failure after timely maintenance is totally on MSR. And I cannot see how even "old gas" should affect pump parts.

I know a guy when I lived in Pennsylvania who had an MSR pump failure similar to yours. He called MSR and they sent him a new pump right away, no charge.

Personally I think that if MSR plans to stay with the same design they need to use DELRIN engineering grade polymer parts instead of the frikkin' cheap plactic parts they now use. Stoves are CRITICAL in winter camping.

You mentioned the stove is only a few years old. The white disc sounds like part of the check valve for an older, yellow MSR pump. Yours should have had a spring and ball check valve. Do you have pics? MSR's worst pumps were the red/blue ones, cracking on the bit that holds the plunger to the tube.
Coleman Fuel will last years in a tightly sealed, metal can. I managed a convenience store for years and everyone blames fuel for their issues. I have a number of MSR pumps and stoves, I can take one apart and see what's down there. I've always returned to MSR the red/blue pumps I received from folks as they arrived with the part I mentioned cracked already, even one new pump. MSR's take on using plastic is the plastic will melt and release fuel slowly and not explode. I have three Primus/Brunton pumps for my 11 Explorer and Nova, that use the CEJN? fitting to attach the stove to the pump. They can have a NRV valve failure and cause a worse problem than a MSR pump unless the check valve in the MSR pump breaks apart, but the newer MSR pumps have a poppet valve, which may stop that, I have not read up on it so shooting the breeze there.
Duane
PS, the other stoves may have a tiny filter, which if plugged will not allow the stove to function properly. I had that happen on my Nova a month ago, luckily I had my 11 Explorer too and was able to diagnose the problem after I got home. I just removed the small filter.
PPS, did you assemble the pump correctly after performing maintenance?

Wild guess–that "white substance" couldn't have been hardened (frozen) grease, could it? Haven't used mine in a while, but over time have been repeatedly surprised how often you should lube the leather plunger that drives the air. Spent too much time cleaning the line due to low pressure when all I had to do was lube the plunger. Don't know the official lubricant, but possibly some too-solid grease is a peril in waiting. Not bad gas. I strongly suspect the only "bad" gas ever gets is (not counting dirt) atmospheric water it absorbs over time. So the stove runs rough, pings, & knocks a little. Meh. No harm to parts.

I went to REI today and purchased a new replacement pump. I plan to contact MSR/Cascade Designs tomorrow to ask about replacing the broken one.

Here is a picture of the old pump and the new pump. As you can see, they are identical. I've pointed to the areas where plastic has broken off on the original.

Here is a shot looking into the new pump. You can clearly see the white material down in the bottom. That's what I popped out, thinking it was some sort of hardened debris or contaminant. I'm not sure what purpose it serves, but now I know that it's part of the pump design. :-/

Definitely not a result of using old fuel. The whole "bad white gas" issue is questionable, but if it does occur, what you'd get would be poor combustion performance and maybe clogging of filters or orifices. Not breakdown of pump components. I have in the past stored my MSR pump in the bottle with fuel in it for long periods of time with no issues. I do have to lube the pump leather regularly to ensure a good seal in there. Mostly I've used Sno-Seal. May not be officially approved, but seems to work.
Your issue is different, and I'd get in touch with MSR customer service.

And BTW, I've been using MSR stoves for snow camping since the late 70's, and the worst thing I've had happen is a clogged fuel line cable. I generally take the precaution of cleaning the fuel line cable before a trip if it's been sitting a long time, and doing a test run before I pack it up.

Well, there was the time I brought the stove, the windscreen, the fuel bottle – but not the pump. But I guess I can't blame that on MSR.

Could have been a bad part. Putting too much "English" maybe on the pump plunger or you cracked it during the rebuild? :) Do you recall if having to hold the plunger hard to maybe replace the pump cup or something else? I'll have to look at that style of pump when I get home Friday.
Duane

"And BTW, I've been using MSR stoves for snow camping since the late 70's, and the worst thing I've had happen is a clogged fuel line cable."

Exactly the same for me. Plus, now I know how to clear the clogged fuel line problem.

The problem described here doesn't sound right for bad fuel. Bad fuel tends to make clogged fuel lines or clogged filters. Is it possible that some foreign object got into the fuel tank by accident, and then it dissolved in there? I'm just guessing.

If I were going out now for a winter trip, I would not consider taking any stove other than one of my MSR white gas stoves.

–B.G.–

Known problem with injection molded plastic MSR pumps, for many years.

My personal opinion is that they made a bad engineering (or management/accounting) decision when they went with that design and that plastic. I am sure cost had something to do with it. One of my other white gas stoves has a metal pump: never any problems.

Ask for a free replacement. MSR are not that bad to deal with. Then maybe find a metal pump.

Or go canister. :-)

Cheers

"Some people blame "bad fuel", so I searched for that. What's bad "Coleman fuel"? In other words, can anyone explain what happens to the fuel when it goes bad? Do some of the volatile chemical compounds evaporate in storage?"

White gas is a mix of hydrocarbon fuels. some fuel molecules have low boiling point while others have a higher boiling point. If the can is not properly sealed when it is in storage the hydrocarbons with a low boiling point will evaporate leaving only the high boiling point fuels left. This can cause the fuel to get thicker and the fuel may not burn as well.

So white gas stored in a can with loose through evaporation to effect stove performance after only a year. However if the cap is on tightly there will be no evaporative loss and the fuel will stay good for years.

Coleman and other companies buy the white gas from refineries. If low quality fuel is purchased it may have some waxes dissolved in the fuel. The white residue you saw might have been a buildup of solid wax. That might or might not have played a role in the pump failure.

"Does the fuel undergo some sort of chemical or physical change? I know that automobile gasoline (petrol) can go bad, turning into a varnish like substance. Does something similar happen to stove fuel?"

It's mainly a physical change. Same thing happens in gasoline except gasoline normally has some wax and oils in it and fewer low boil point hydrocarbons in it. White gas has fewer oils and waxes.

note that in some gasoline cans and all car fuel caps have pressure relief valves built in so that on a hot day some of the evaporated fuel will vent reducing the pressure in can or tank. For a small amount of white gas stove fuel you want to stor it in a tightly sealed can without a pressure relief vent

I wanted to post a follow-up regarding this incident.

I obtained an RMA number from MSR and sent in my failed stove pump.

Late last week, I received a package from MSR. It contained my original pump, but with a new plunger, thus fixing what I reported as broken.

So, points to MSR for repairing my broken pump free of charge.

Thanks to all who provided insight and commentary. I view MSR's plastic pump as not terribly reliable now due to this experience.

I'm wondering if the collar that looks like is the broken part, was not seated properly and was loose. I don't use my more modern MSR stoves enough, to get enough trips on them to test for longevity. If the pump cup was still intact, you should have been able to still pressurize the fuel bottle, by keeping the plunger centered in the pump tube. There are more stove options out there you can try.
Duane

Duane,

It didn't appear to be seated any differently than on the working pump. Maybe the broken bits above the rubber plunger allowed the rubber to deform under pressure so that air could escape back up the tube?

I spent a short amount of time window shopping online for stoves made by Primus and Optimus. For now, I'm not going to invest any more money into my white gas stoves, though I would probably reconsider if I began doing more long winter treks.

Jeff

I can see you not being confident in MSR then. They have sold tons of stoves and back all their equipment. If looking at similar type stoves, be aware some have a tiny filter somewhere in the fuel line if you don't know already. Be aware that is their Achilles heel from my reading. I had my Primus Omnifuel peter out. When I got home, the tiny filter was pretty dirty. It was a recent flea bay purchase for me. Luckily, I collect stoves and had one other with me. The Omnifuel could have finished breakfast, but at a very low flame. Good luck in your selection if moving on.
Duane

I had an incident over the holiday weekend when I was at 7000' near Lake Tahoe. My 2-year-old MSR Simmerlite was assembled, then pumped up moderately. When I started to turn the fuel valve, fuel was leaking up around the brass valve stem. On the first try, I did not see the fuel until it was too late, so I had a mini-inferno on my hands. A splash of water put that out. It did the same for two more tries. I got my meals cooked, because the leak would always stop by the time the flame went blue.

Now I have to decide what to do. I could try to disassemble the thing and look for a damaged O-ring. I could take it back to REI. I don't know if REI still tries to repair that stuff. I'm probably better off on my own, assuming that I can get parts.

The pump has one part that needs to be lubricated, but I don't know about the fuel valve. I guess I need to find the exploded assembly diagram to work with before the whole thing actually explodes.

–B.G.–

I've had a leak like that happen with my older pump (Al knob, grey/black pump). I turned around after the first night (out of 3) because of that. Temperatures were single digits, I'm sure.
The pump worked perfectly back home at 60F.
I replaced the valve O-ring (sourced at O'reilys) and that fixed the leak.

Geez, Bob, that seems like a full assembly warranty replacement by REI. Only replacement parts I've seen always come in a $$ more-parts-than-you need kit. Of course if you know your o-rings…. Do not explode. (Remember when they used to fire up stoves in REI to show you how they worked? Thinking repairs died closely after that practice passed away.)

Jeff–is your plunger really rubber? I went & broke down my not-young one & it definitely is leather. It needs lubrication, while rubber shouldn't at all. There must absolutely be a one-way-valve at the cylinder bottom, so plunger failure should not lead to decompression. Just prevent commpression. Still curious about the white stuff. All mine has at the bottom is a screen and ball bearing (probably the one-way stopper). Those plastic parts look like what might break from over-vigorous pumping. Good luck.

You all have inspired several test firings.

Now you guys have me wondering if I should get a spare pump?

Pumps do not just fail on their own, for no apparent reason. Nearly always there is a small component failure like an O-ring, or a plunger leather that isn't lubricated. In almost 35 years of using MSR stoves, I have never had a complete failure in the field. I've seen leaks and clogs and all of the usual stuff.

If I ever see plastic sediment in a fuel bottle, pump, or under the burner, it can be traced to plastic flakes that had gotten into the original Coleman fuel can and then partially dissolved there.

–B.G.–

The control valve o-ring is in the annual maintenance kit (at least they used to be). Can also find the o-rings at the hardware store. I use the little tube of oil that comes with the kit to lube it every year if the o-ring is okay.

msr o'rings.
this is a subject that was hased out inteh early days of bpl. here's the deal. box store and auto shop o'rings are often caca. real industrial o'rings come from bearing supply houses. they cost in lots of 100, essentially nothing.
the size chart you want is at Mcmaster.com
if you request o'rings by number (it's a universal sort of thing) the bearing supply guys will treat you vastly better.
if you send your wife to pick them up, they might well be free.
the standard buna variety of ring is sufficient for our purposes.

there is no need to buy a msr kit to source quality o'rings.

Based on the recent fuel leak, I purchased the MSR maintenance kit since it has the wrench tool, the O-rings, the lubricant, and the instructions. The first O-ring that I went after was inside the fuel control valve stem. It seemed to be normal, so I just cleaned and lubricated it. The fuel still leaked. The second O-ring that I went after was inside where the flexible fuel line plugs into the pump assembly. It also seemed normal except for some red gunk around it, so I cleaned it off and lubricated it. Then everything worked OK. There are three or four other flexible rubber/plastic parts that I didn't fool with.

–B.G.–

…be aware some [MSR stoves] have a tiny filter somewhere in the fuel line if you don’t know already. Be aware that is their Achilles heel from my reading.

Yes, but that’s only the DragonFly. The in-line filter is a completely idiotic design in my opinion. That and the DragonFly uses an entirely different pump than all other MSR stoves that use a pump. Not my favorite stove if you can’t tell.

The latest MSR pumps have the filter where it belongs: Externally, on the fuel intake.

HJ
Adventures In Stoving
Hikin’ Jim’s Blog

Jeff–is your plunger really rubber?

Yes, the latest version of MSR pumps (which Jeff has; I can tell by the photo) have a synthetic rubber pump cup. They don’t need lubrication the way the older leather pump cups did. Still, a bit of lube will give a better seal.

You do have to be somewhat careful as to what type of lubricant is used in cold weather. Very cold weather could cause the lubricant to congeal which could potentially cause the plunger to freeze up or at least render it very difficult to pump. In those conditions, a breakage (like that described by Jeff) could occur.

It actually is a smart idea to have multiple stoves along all using the same fuel (and perhaps parts too). Remote canister stoves will generally be more mechanically reliable than white gas/kerosene type pressure stoves (no pump to fail). Of course if your canister gas gets cold for any reason, you are screwed in really cold weather. Depending on the group size and composition, what I’ve often thought would be ideal would be to bring a combination of liquid fueled and remote canister stoves.

HJ
Adventures In Stoving
Hikin’ Jim’s Blog

> the standard buna variety of ring is sufficient for our purposes.
Buna N (Nitrile) will probably work OK in the tank, but for the tiny difference in price I would prefer Viton. However, Buna only goes up to about 100 C, so don't use it on the stove body: use Viton.

Cheers