This is Curtsey of the:

The plunger stem rises after I pump it up.

How This Part Works:

At the bottom of the pump plunger cylinder is a check valve. This device temporarily keeps pressurized air from leaking out of the fount or tank, until it is locked-out by the air stem. When you are pressurizing the appliance the check valve will hold in the air during your up-stokes, and then again before you have a chance to turn the plunger fully clockwise. In the blow figure, the check valve is in light-orange. Note the small check ball in the center of it, in bright yellow.

For more information go to our Theory of Operation chapter.

Why it is Not Working Properly:

Over time the check ball and the inside of the check valve will corrode and varnish will collect. This will create a situation where the check ball cannot properly seat itself in the valve. If you pressurize the appliance and then just rest your finger over the hole in the pump before you lock it clock-wise, see if it raises. If it does then the check valve is leaking.

How To Fix It:

Replacing a check valve is no easy task. But before you get worried I will tell you that a "good" check valve is not required for the lantern or stove to operate correctly. When you are done pressurizing it, keep your thumb over the hole and keep pushing down and then turn the stem clockwise to lock it with your other hand. Once locked, the check valve is no longer in use and the air stem has the passage completely blocked off. If you do wish to replace the check valve please refer to our Rebuild Instructions.