Too much liquid in the tank. The sprayer has raised fill markings on the side of the tank – only fill to the max fill line. This will allow enough room in the tank for the air/pressure needed to allow the sprayer to function properly.
Inspect pump piston o-ring. Depressurize the sprayer and remove the pump from the tank. You will need to separate the pump piston from the pump barrel. Squeeze the two tabs on the cap and pull away from the barrel (See Figure 4). At the end of the metal piston/rod, there will be an o-ring (See Figure 5). Periodically this o-ring needs to be lubricated with a heavy coating of petroleum jelly to ensure a nice tight seal in the pump barrel – delivering as much air as possible per stroke. If you find this o-ring seal to be worn, damaged, or swollen, it will need to be replaced by ordering a pump service kit.*
