unloader valve already covered. but have experienced problems with "low pressure" or not enough water coming from the house garden faucet. result was the pressure washer would begin cavitation (pulling air out of the water). and i would need to wait every few minutes. to let the air clear the lines again. and for the pump to re build up the pressure.
long story short. house plumbing was old, and was crusted up with lime. causing what should been a 1/2" pipe reduced down to 1/4" if that pipe. after replacing house plumbing, never had an issue again with the pressure washer.
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now, a few weeks back, got a new pressure washer, and was testing it out, my pup can not get enough of chasing water coming out the garden hose. figure i would shoot some spray up into the air for him to chase the spray (was making sure he never got into the actual high pressure stream of water). i was constantly open/close the trigger on the gun. and i do believe caused cavitation within the pressure washer that caused an air lock. ((only got a trickle of water coming out of nozzle)), i ended up needing to shut pressure washer off, and pulling trigger on gun. to let all the air out of the system. turned pressure washer back on, pulled trigger on gun, and all was fine once again.
*shrugs*
