Sorry for the dumb question I guess I never noticed it.Ozman;
When you position/set the psi gauge at 400 (as an example) and then you press the trigger on the wand, where do you think the pressure goes to? You are demanding that it travels through your pressure hose to your wand and through your jets. Thus, it is common that you will, or might have a pressure drop to zero.
(dependent on your jet openings will also determine your pressure drop!)
Hope this helps;
I thought so, it usually does but not all the way to zero.Usually that happens after you run your p ui mp dry and you have an air bubble in your system. Take the end off a solution line and run it for a minute. That clears the line. It usually will drop some when uh ou trigger the wand, but not to 0.