This is Curtsey of the:
Loses pressure right away or within a few minutes of pumping.
How This Part Works:
There are three holes in a lantern fount or a stove tank. First if the filler hole that you use to pour fuel into. This hole is plugged by the fuel filler cap. The second hole is where the pump is in. By turning the pump stem fully clockwise you lock this passage off. Lastly is the hole where the valve is and it is sealed in by threads and tension. Unless it is allowed to escape, or it finds an "unauthorized" escape route. A fully pressurized and operating stove or lantern should burn bright for hours without having to re-pressurize. If not in use a tank or fount that is pressurized to 45psi or so should stay that way for a very long time.
For more information go to our Theory of Operation chapter.
Why it is Not Working Properly:
There are only three ways for pressure to escape: the valve is open, the fuel cap is leaking or the pump check valve is leaking. Ninety-nine times out of a hundred the culprit is the fuel filler cap.
How To Fix It:
You only need to replace the cap and the correct part number is 220C1401. You can get this part at most sporting goods stores or I have it on this website for $2.55. If you have a 242/243 lantern or a 500 stove you will need to replace the insert gasket as Coleman does not sell the smaller replacement caps any longer. To replace this gasket please refer to our Rebuild Instructions.