What causes pressure washer not to foam?

Answer 1

A foam injector (AKA foamer or foam cannon) can be attached to the end of a pressure washer wand to transform the detergent or cleaner you are working with into a thick foam that will stick to a surface for longer than a viscous liquid. This will enable the chemical to clean more thoroughly. There are a couple of different types of foam injectors, and there are several reasons that it may not function properly.

Some foam injectors do not have a bottle reservoir attachment, so they must be used with a chemical injector (a mechanism for injecting chemicals or soap into the water stream). If this is the case, the problem might be with the chemical injector. Remove the foam injector and use your chemical injector without it. Look at the bucket of chemical to see if it is being siphoned. If it is not, a couple of things may be wrong (the same things might be wrong with your foam injector if it uses a bottle reservoir):

• The specs (I.E. the PSI and GPM) of your machine may not be compatible with the chemical or foam injector. Check with the manufacturer of the chemical/foam injector to find out what the maximum and minimum operational specs are.
• Your nozzle might be clogged. Chemical/foam injectors work off of the Venturi effect. The Venturi effect occurs when a restriction in the pipe that the fluid is flowing through causes a drop in the fluid's pressure.1 This drop in pressure can be used in pressure washing to draw chemicals up a hose and into your water stream. The nozzle that causes this restriction needs to be at a precise size to cause the desired draw. If this nozzle is clogged, the nozzle can become too constricted and not function properly.

If neither of these things are the case the problem might be with your pressure washer or chemical:

• If your chemical is old, too diluted, or not effective, it may not foam up properly. Try a different chemical and see if it works then. If you get foam with a new chemical, then the fault was with your old chemical.
• If your pressure washer is not getting enough water on the inlet side, word, not getting enough fuel (there are a multitude of reasons for this) you may not getting the pressure that you expect out of the pump. Check the pressure on the outlet side of the pump with a pressure gauge to see if you are getting the pressures you should. If not, then have a mechanic look at your pressure washer.