Now working on getting a 991 up and running. I thought it would be easy since it seemed to pressurize and I thought I tested the jet and just installed a mantle. Turns out it is going to be more interesting. No fuel comes out of the jet. Turns out the pricker needle is stuck in the jet. It could very well be due to some mishandling from my part. I did a double priming as this is sometimes needed and I didn't want to soot things up and flare up indoors. I might also have turned the valve when I'm not supposed to. Anyway now I would like to get the jet cleared and try to avoid any mishandling in the future. I might have made a similar mistake on my 1020. I just saw that the old jet also had the needle stuck in it (I replaced the jet with a new one).
Hi @kephart there is a thread about using Alum which dissolves the Steel but not Brass? here is a screenshot of the thread ; when you find it there are more images which look encouraging cheers pb
I tried soaking it in citric acid and it seemed to work. At least I can see through it. I'm thinking it probably dissolved the carbon soot that made it stuck.
The fettling of this lamp turned out to a be a lot harder than I thought. When the jet was cleaned it still didn't pressurize. I suspected a bad tank lid gasket so I decided to make a new one from a retro lemonade bottle. It seemed to work and I tested it on a working Primus 1020 which has the same dimensions. I also wanted to check the pump leather but it again turned out to work well on the 1020. I now had my suspicions about the NRV. I had to push hard and add some kerosene in the pump tube to get it unstuck. It didn't feel quite right pumping either. I tried to remove it with the correct Primus-tool and it unscrewed easily, but didn't come out. A lot of wiggling and mild prodding with some steelwire finally made it fall out. I unscrewed it and inspected the pip. It looked a bit short and was made of cork from what I can tell. I decided to change it, but would like to fix it at some point, but I had no Viton-rubber at hand and no nitrile either as far as I know, but maybe I could have scavenged some from an old lawnmover fuel hose or something. Now finally it sprayed fuel out of the jet. Time to test it. A lot of burning from odd places, spilled fuel perhaps? A bit surprised by the amount of burning on the lid. Finally it shines strong:
I think I know what the "burning hat" was about. Since the pricker needle is gone it is not a good idea to pump it up before priming is done. It sprays unburnt fuel all over the place. I might need to get a new pricker.
The pricker is not meant to close off the jet, it is only for cleaning. You should not start pumping until the lamp is fully pre-heated.
That's the whole point, there is no valve in a 991. All it is is a mechanism to raise and lower the cleaning needle. The lamp is not designed to hold pressure while it is not being used.
