Initially, check out how much oil is in the oil tank right now. If you see that the oil is mixed with water, remove it from the tank through a siphon and add the oil for pressure washers. Make sure that you add the required amount of oil. Now press the primer a couple of times (can be found on the side of the washer) if you see that the flow is still weak. Disconnect the discharge hose from the pump and release the remaining air. Connect it again and try to restart the pressure washer. If these steps are not helpful at all, you should better go to the specialist.