Tuesday, 16 October 2012

Unblocking my orifice

On the recent Ben Vorlich/Stuc a Chroin trip my trusty stove stopped being quite so trusty. It didn't completely stop and all would have been OK even if it had, as Davy and Michael both had stoves I could have used but it was annoying to say the least.

The Primus Express spider has pretty much been my "go to" stove since I got it and it's been on pretty much every trip ever since. It's fast, powerful and compact. It works well in winter conditions and has brought me much joy in the form of hot cuppas and dinners on cold summits. To say I was a little disappointed when it stopped working would be an understatement!

On the trip I had already fired it up and used it twice already. Once for a hot coffee as soon as the tent was up and once for dinner. It was when boiling some water for a bedtime cocoa that the power output just decided to drop right off to the equivalent of the minimum setting and wouldn't allow me to adjust it. I was using a Primus 100 size cartridge at the time also. I did manage to get the water boiled, although it was pretty slow. Again I used it successfully, albeit slowly in the morning for porridge/coffee.

Upon returning home I tried it again on the bench with another cartridge with the same results, and then tried both of those cartridges in another stove which was fine. The problem was most definitely my stove. I fired off an email to Primus which promptly bounced back as undeliverable. A little more digging on the 'tinternet revealed that it's Rosker who distribute Primus stuff here in the UK. An email to Rosker elicited a very quick response containing some advice as to the likely cause of my issue and an instruction manual on stripping/servicing my stove. Brilliant service!

Turns out I had a blocked fuel jet. (Item 9 on the wee diagram below)

10 minutes with a pair of water-pump pliers, an 8mm spanner and the wee jet unblocker needle doodah from my old MSR Dragonfly and I was back in business. Hoorah! I'd never have guessed it though. A blocked jet from a gas stove? I've only ever seen that with multi-fuel stoves and dirty, sooty fuel. Maybe it was from using the gas stove in liquid feed mode? A wee bit of crud from inside the canister perhaps or maybe its from any remaining impurities (swarf or coolant from manufacturing?) that were already in the fuel line where the pre-heat coil goes over the burner getting carbonised? Who knows? It's working and that makes me a happy bunny again! I'll maybe even celebrate with a cuppa on a hill-top somewhere soon!

It got me thinking though. Maybe I should carry the wee tool with me to prevent something like this potentially ruining future trips? I don't have a tool supplied with my Primus stove but I do have one from my old MSR and being a maintenance technician and Land Rover owner I have more spanners and hammers than most folk at my disposal here at home. Turns out the MSR tool, although fine for unblocking the jet has the wrong size spanner. Ok I'll just get the Primus one (Item 13 in the diagram) then say's I, but upon checking the sizes of the spanner part before I clicked "buy now" I noticed a fatal flaw. I had had to use a pair of water-pump pliers here at home to loosen and remove the knurled nut (Item 14 in the diagram) and it took a decent amount of force to do so. I don't see anyway that you could do that in the field with that wee multi-tool. I'd still have been snookered on the hill top unless I had my proper pliers with me (most unlikely!) Why then not make it a hex nut with flats on it that their multi-tool fits? I shall feed this back to Rosker/Primus and see what they say.


  1. Would have carrying a leatherman help for field repairs. They have pliers?

  2. I suppose they could have helped but I'd never carry one, again too heavy for something Id hardly ever use...saying that I carry a gerber miniature multi-tool gizmo all the time on my keys but it'd have been no use its the one with scissors instead of a knife.

    Got an email back from Rosker, they say the knurled nut should only be done up hand tight so I'm off too loosen mine off!

  3. Scissors instead of pliers even...

  4. Hi, I try to reach you this way because I couldn´t find an e-mail.
    I started a blog about the nature of the Cantabrian Mountains (northern Spain), which will have a lot of information about walking and landscape, and also about wild flowers (orchids), animals and geology which can be found in this region.
    I think those mountains are a lovely place for walking.
    The link is: wildnaturespain.blogspot.com.es
    I invite you to have a look, and if you think it´s worth it, I would appreciate a link from your website.

    Sincerely yours,

    Marius van Heiningen

  5. Nice site Marius, I particularly like the winter photo's. I've added a link to you on the sidebar there.



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