Pressure washer problem

[Another John]

Howdy,

My "Powercraft" pressure washer (an Aldi product, bought 5 years ago) has just started to "hunt": a pretty un-technical term, but it resembles that phenomenon in an engine, and it also echoes the noise it makes ...

Washer is switched on -- I pull the trigger -- the pump starts up and the pressure jet shoots out as required. I release the trigger, the jets stops, the pump stops .... but then it starts to "hunt", i.e. switches on for a fraction of a second, repeatedly, until I pull the trigger again.

I presume this is related to the pressure switch, somehow: has anyone any suggestion for fixing it? It can't be doing the machine any good!

It only started doing this yesterday, after years of trouble-free use (though I've never used it intensively).

Cheers John

[Harry Bloomfield]

Another John pretended :

A bit of a guess here...

The idea is that if you release the trigger, the pressure builds up and switches the pump off. So either the pressure is leaking away, or the pressure switch might be set to high.

The leak could be via the one way valve between pump and hose, including where the pressure switch is located. In the hose, its connections, or the lance before the trigger.

Make sure you disconnect power and release pressure via the trigger, before messing with it - they store some serious pressure.

[Mike Barnes]

Another John :

When my Karcher started doing that it was a slight leak on the high pressure side (split plastic moulding). When the pressure drops below a certain level, the motor starts, gets up to full pressure, stops, then the pressure starts dropping again.

[Nthkentman]

Mine does the same, different make though. I just turn the unit off between uses not worth farting around with really.

[The Medway Handyman]

It could be the pressure switch, but more likely a small leak on the high pressure side will cause exactly this fault.

Check the 'o' rings where the hose leaves the machine, joins the gun etc.

If it is the pressure switch it just needs a 'tiny' adjustment.

[Norman Billingham]

My Karcher has done that since it was brand new - I assumed it was normal!

[John Rumm]

Indeed - a new set from ebay fixed this feature on mine...

[John Rumm]

I have noticed that you can get this behaviour if you don't purge all the air from it first before powering up - so let water run through it until it is coming out of the lance without any interruptions or "clicks" as air is ejected.

[The Medway Handyman]

Best way to start any pressure washer;

Connect to tap. Remove lance, open gun, allow water to clear air. With gun still open & no lance, switch on. When you have a nice even flow, fit lance & carry on.

[Another John]

OP here: *Brilliant*!

A classic example of the way this group works: thanks very much for all the instant responses, chaps. I will pursue the various possibilities. It's like being lost, and then a helpful passer-by giving you a map!

Thanks again John