Why does the pressure vary from high to low? Cause Solution Not enough inlet water supply. Turn water on fully. Check garden hose for kinks, leaks or blockage. Pump is sucking air. Check that hoses and fittings are airtight. Turn "OFF" machine, and purge pump by squeezing trigger gun until a steady flow of water emerges through the nozzle. Water inlet filter is clogged. Remove filter and rinse in warm water. Discharge nozzle is obstructed. Blow out or remove debris with the needle clean out tool. Calcified gun, hose or power nozzle. Run distilled white vinegar through the detergent tank, or soak the calcified part with the vinegar. Related articles My pressure washer is leaking from where the garden hose goes into the pressure washer. I just got my pressure washer, and I am missing the needle clean out tool. Pressure Washer What is the coverage area of the Aqua Joe AJ-IST39BM? My unit has low or lack of suction.