Hello, I just fired up my Primus No. 71 stove, from 1947 (AL) for the first time since I've received it (~1990). She likely hasn't been lit for at least 40 years and the fuel tank has been stored empty for that same duration. I filled her tank with fresh Coleman fuel and let it sit for an hour before attempting to lite it. Following the instructions I let a bit of the fuel collect in the priming area, lit that and soon after (15 secs) the gas became vaporized and blue flame output. I kept her running for 30 minutes or so but the flame gradually lost intensity to the point I'd describe it as 'simmer' only in terms of heat output. Is this due to the tank not holding sufficient pressure due to the original seal (or gasket) on the fuel cap likely needs replacing? Any other issue that would cause this? Thanks for any input.
Hi Smolson loss of tank pressure could well be the cause, but being as it was working fine for 30 mins it could be another reason unless at that point the filler cap washer started to leak. Being as the stove was running for 30 mins was it low on fuel? Also the jet may have started to be come blocked with carbon or the cotton wick may have become fouled with dirt/residue from the tank if it was not flushed out after it had not been used for 40 years, adding new fuel to the tank that may have dried up residue in the new fuel would have dissolved the residue in the tank and drawing it up in to the burner and then causing carbon build up I the burner, all so the wick can become charred preventing the fuel from being drawn up in to the burner effectively. Another point even though these stoves were made to work using white gas a lot of the time leaded petrol/gasoline was used which would soon gum up the burner preventing it from working effectively. These are the main problems that cause these stoves from working effectively loss of pressure or carbon build up.
Gradually loss of flame seems to me would indicate loss of pressure. However, if it had run for quite awhile before doing that, running out of fuel per symptoms of my 123's. Check for slight leak of the fuel cap, may need to replace the washer. Seems a clogged jet would cause issues too, prick it. Duane
Thanks for the reply Mr. Optimus. I rechecked the stove and did notice the fuel cap wasn't tightened properly (perhaps the heat loosened it?) and refired it. Had it running again for 30 minutes but this time there was no decrease in the heat intensity (consistent blue flame), she boiled up a pot of water, consistently sounded like a jet engine (to me anyway), very little to no yellow flame (intermetent at best) so it seems to be working fine. The tank was full so running out of gas wasn't the issue (I only wanted it to run 30 minutes, after that I just shut her off). Talk about a workhorse/build quality. To be fired up after at least 40 years of no use is quite impressive. The tank does get hot though (to touch) when the stove is running - I'm assuming that's normal? I'll be using it (and a running model 530 Coleman also from 1947) this weekend on a canoe trip (Algonquin Park) so will post picts next week. Thanks again.
Hi Duane, Thanks - yes I did 'prick' the fuel nozzle piece with the nipple cleaner tool that came with the stove before I first attempted to lite it. Did this tool 'hang' anywhere inside its case or on the stove itself or was it just placed loosely in there when packing? I'm surprised the tool is still with the stove given it's small size and flimsy build (easy to bend and lose).
SMolson, welcome tp the forum. You might want to check the fuel cap gasket, remove it and see if it is still pliable, you know, the old fanbelt check. Also make sure the nipple is snug and no pressure leaking from that. If you PM me your address I will send you a few viton rubber scraps you might want to make a new gasket plus a spare for CYA Chef BC
Thank you Chef BC for the kind offer. I am unfamiliar with how this forum works so not sure how to 'PM' you within its structure. Some forums have an embedded email link associated to their user names but this one doesn't seem to (assuming you wanted me to email you my address info). To answer your questions - there is no pressure leak from the nipple, it appears to be solidly closed when the stove is turned off (no visible gas discharge or sound heard). The fuel cap gasket is held (or supported) in place by a screw. I did remove the screw but the gasket appeared stiff (and potentially brittle) so I did not want to risk prying it out and have it crack.
After all those years it is well worth replacing the filler cap seal. It should be soft and rubbery but it is probably like hard plastic. It may hold pressure now but it will let you down again when you need it most (bitter experience speaking here).
The Primus catalogues claimed one and a half hours for the Primus 71 but that was probably at a low setting. Plus, there was no advertising legislation back in those days - you could claim what you want.
Thanks again. Yes the filler cap seal (aka fuel cap gasket) condition is that of hard plastic. Once I have the proper replacement do I just 'pry' the old one out using a small screwdriver - it will likely break in small pieces during that process but I will fish it all out from the cap. If I have to cut a gasket myself do I just use a sharp knife and cut in a circle using the fuel cap as a size template and then just shave it carefully to size afterwards? After 2 runs of roughly ~30 minues each time the fuel tank had about 1/4 of gas remaining (~1/4 volume of the tank capacity). The fuel tank on this 71 is rather large for her size, approximately 200 ml would be my guess. I checked my Primus No. 5 J-nr and her gasket is likewise black hard plastic. The leather washer on the pump has also dried out and needs replacing.
You could crudely cut out rubber but the rubber suggested is viton or nitrile of good quality as it withstands (not imprevious) to gasoline or coleman fuel. Alternatively a hollow punch with the correct diameter would work if you have one. For leather pump cups, our member safaudi makes/sells them and they are by far much better. You just need to know the correct diameter as pump cup sizes differ. Same thing, you could crudely make one. Google how to form leather into shape. PS. He sells them also on ebay. Ron
Thank you. For diameter of the leather, I'm assuming it'll be the inside diameter of the pump tube? A fellow from Turkey (sefaudi you mention) seems to have a good selection of them for the type I'm looking to replace. I have no experience working with leather and I don't have or know someone with a punch. I'll ask around town to determine where I can pickup viton or nitrile rubber (Home Hardware/Home Depot/Rona/Plumbing supply store/etc) and what thickness I need.
Hello ! I use to make my leather pumps very quickly, without punch. It's not elegant, but works fine and take 3 minutes. You can google-translate this link and give it a try.
Thanks Nikos! I think I can handle that process, lol, looks quite simple yet functional. I also finally found some citric acid crystals - at the Bulk Barn in a small jar ($4.00 Cdn for 1/3 cup or 100 ml). Will follow recommendations from another post in terms of ratio to water and clean times, testing it on a burner ring from my Peak 1 and go from there.
