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How to Use a Dewalt DP 3100 Pressure Washer

Kelly Nuttall

DeWalt pressure washers are useful for everyday property maintenance and cleaning, building washing, vehicle washing and even heavy-duty paint stripping, degreasing and cleaning projects.

DeWalt numbers its pressure washers according to the maximum psi (pounds per square inch) capacity of the tool, so the DP 3100 can produce a maximum of 3,100 psi. It is very important to know how to safely use a machine that can produce that degree of power. Learn how to use the Dewalt DP 3100 pressure washer before attempting to operate it.

  1. Be sure the pressure washer, the gun, hose and washer tip are assembled correctly. If water leaks out of the hose or any of the connections, shut the pressure washer off immediately.

  2. Place the unit in a well-ventilated area. Make sure the gas tank is full. Check the engine oil level and add oil if it is low. Connect the water supply hose (usually a typical garden hose does just fine) to the water source and turn the water on to empty the hose of air. Be sure the filter screen is present in the hose connection with the dome pointing out away from the pump. Connect the water supply hose to the pump connection. Turn the water source on. If the water is not on when you start the engine, the pump could be damaged. Remove air from the pressure washer system by pulling on the gun trigger until water comes out.

  3. Turn the engine’s on/off switch to “on” and be sure the fuel valve is in the open position. Close the choke if the engine is cold and pull on the starter rope until the engine catches and runs. Open the choke as the engine warms up. Pull on the gun trigger to begin washing. To shut the engine off, turn the on/off switch to “off.”

  4. Adjust the pressure coming out of the gun by doing one or a combination of the following: back away from the surface you are washing; use the white 40-degree washer tip; reduce the speed of the engine (the engine speed directly affects the pressure delivered through the system).

  5. Change the spray nozzle by turning the engine off and releasing the pressure in the system. Pull back on the quick-release attachment to release the connected nozzle and insert the desired nozzle. Turn the engine back on and proceed with washing.

  6. Apply cleaning chemicals and solvents through the included chemical hose. Attach the chemical hose to the barb located near the high-pressure hose connection. Place the screened end of the chemical hose directly into the bottle of cleaning solution. Insert the black, low-pressure nozzle following the instructions given in Step 3. Detach and rinse the chemical hose out with clean water after each use.