pre heating 425F

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pre heating 425F


Post by jcoddou »

At below freezing temps I have fuel leaking out the rear of the manifold of a 425F after pumping. I tried lighting a piece of wax in the burner for preheat, and it seemed to work OK. Is that normal, or should I have to preheat a 425F in temps 32 Degrees F or below?
And at certain temps do you have to warm the fuel, also?
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Re: pre heating 425F


Post by dbhost »

I'm not sure I understand the question. You must heat up the generator no matter the temparature on any PGA stove. On my 425E I pump, flip the light lever, open the valve and light, once the fuel starts vaporizing correctly, typically about 30 -45 seconds depeding on the weather / wind etc... turn the light valve to run, pump up again to top the pressure off, and adjust flame.

Other than the amount of time it may take to actually get the gas to effectively vaporize, temperature, at least any termperature I have been willing to be out in, doesn't really seem to matter. You should theoretically have to preheat the generator above 32 deg F. I follow the preheat procedure even when it is is the upper 90s F....
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Re: pre heating 425F


Post by zoomkat »

"At below freezing temps I have fuel leaking out the rear of the manifold of a 425F after pumping."

Assuming the fuel control valve is not leaking, what position do you have the start lever in when you try to light it?
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Re: pre heating 425F


Post by Kgam1020 »

After you pump up your stove does fuel automatically start flooding from the mixing chamber? If so then it sounds like the valve isn't closing completely. The tapered tip of the fuel valve might have a groove worn into it allowing fuel to pass by when its actually closed. Easily fixed by lightly filing the tip or adding some solder to the tip and reforming the tip angle with a file. I have camped on some 30 degree mornings and haven't had any problems lighting my 426D.
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Re: pre heating 425F


Post by poppa »

I don't like whump. I preheat everything except for my kero lanterns and the alcohol cup does that for me. A propane torch is so much better than the sorry matches that we have today. On a stove I heat the generator a little bit and turn the needle up any turn the valve on with the torch on the generator and burner and it comes to life. After it burns just a bit I turn the needle down. A torch almost eliminates yellow flame and smut....poppa
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Re: pre heating 425F


Post by Majicwrench »

I'm with zoomkat, I'm not sure I understand your question. Pump all you want, no fuel should leak anywhere till you open valve.
Then with valve open and lever up, better have a flame source at burner. If you don't light it, then you will get fuel puddling places it shouldn't be.

I use a Coleman suitcase (a 417B, which has exact same lighting circuit as yours) on a daily basis, often when quite cool, and I never pre-heat it.
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Re: pre heating 425F


Post by Stovie »

John, I think I understand your question. Yes, it is normal in extreme cold to have to preheat the generator well in order to effect vaporization of the gasoline in order to light. A propane torch is handy for this purpose

BUT, having said that - by way of background - initially with my first "personal" 425 series suitcase stove and no extensive experience I was unsure of their characteristics in cold weather i.e. I didn't know what to expect in terms of performance, because I had nothing to compare. I thought they just were cold blooded beasts and wouldn't throttle down low.

I can say they work much, much better when they are clean internally. It isn't just the generator assembly that is critical, also consider the fuel/air tube inside the tank in particular, all those fine orifice passages need to be free of sludge and gum, they are precision cut. It is pretty simple to disassemble these for cleaning. Interestingly enough the fuel/air tube assembly in my situation didn't look particularly bad, but it improved performance very noticeably. Notably in warmer temperatures it lights instantly and also notably throttles down to a whisper, easily as low as any home kitchen range.
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Re: pre heating 425F


Post by DanLee »

In my salad days, I'd squeeze an inch or so of Mautz Fire Ribbon on the burner under the generator and light it. After it was almost burned out, I'd open the valve and start cooking.
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Re: pre heating 425F


Post by JimL »

As noted above, you need to ensure the lighting lever next to the fuel valve is in the up position when lighting. If you don't, then air won't mix with the fuel and you'll get flooding. It takes a while to burn off that excess fuel and it may be easier to flip the stove over and pour out the excess fuel, or remove the burner and use paper towels to dry the excess fuel since it can take so long for it to evaporate. That being stated, in cold weather, it can help immensely leaving the lever up for an extra minute or so to further heat the generator. When that lever is down, you get straight fuel, but when the generator is sufficiently heated, the generator is vaporizing the fuel which is what you want.

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