Steve, the most accurate way to check psi & gpm on your machine is put a psi gauge on it and pump the output in a bucket and measure it.
You can either mount the psi gauge permanently to the pump or unloader or mount it to a "T" fitting with a quick connect coupling and a plug so you can remove it easily. If you put it in right before the wand, you get your reading considering the pressure drop for the hose. Check the pressure with the trigger pulled and this is your spraying pressure. Remember that you have a positive displacement pump and that it will pump the same gpm as long as the engine rpm stays the same. The nozzle size will determine the psi, so you can control it with larger nozzle sizes. But don't use a smaller size than recommended to give your rated psi. Learning how to use nozzle sizes in your washing is a very useful tool that can greatly increase your washing speed without working harder.
Check your gpm by removing the nozzle from your wand and pumping water into a bucket for exactly a minute, then measure exactly the gallons in the bucket. You can modify this slightly to check the exact percentage your chemical injector draws.
Baldwin Power Wash, Inc. serving the Gulf Coast between Mobile, AL and Pensacola, FL.
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