Karcher doesn't always power up on trigger

[rcx132]

I've watched a few Karcher K2 diagnosis videos but not give any advice for this fault. Sometimes when I pull the trigger then water flows but only at mains pressure, the washer does not power up. Other times it does. Other times it keeps pumping when the trigger is not pulled.

I'm taking it apart now but not sure what to look for.

 

[Cobbler]

Sounds to me like the pressure switch is knacked. Espares do bits for them if needed, also some repair guides & diagrams if I recall from the time mine played up.

 

[the snooper]

I've watched a few Karcher K2 diagnosis videos but not give any advice for this fault. Sometimes when I pull the trigger then water flows but only at mains pressure, the washer does not power up. Other times it does. Other times it keeps pumping when the trigger is not pulled.

I'm taking it apart now but not sure what to look for.

there will be a switch mounted near the high pressure output and a small piston that operates the switch when pressure builds as you release the trigger, either the piston is seizing up or the switch faulty, operate it with the cover removed and you will see if its the piston not moving

 

[cocker]

Our pressure washers all broke because they were left out over winter .
They freeze inside , then do exactly what yours is doing .

 

[Mee]

Or the motor just wears out with age and use.

 

[rcx132]

there will be a switch mounted near the high pressure output and a small piston that operates the switch when pressure builds as you release the trigger, either the piston is seizing up or the switch faulty, operate it with the cover removed and you will see if its the piston not moving

Are you talking about this piston marked red? If so it's not budging at all. I connected mains water and it didn't move. I put my finger on the outlet to build up pressure and still didn't move. It's rock solid.

 

[the snooper]

Can't really see it in the pic it works on the 1000 psi the pump creates not mains pressure

 

[the snooper]

Can't really see it in the pic it works on the 1000 psi the pump creates not mains pressure

Are you talking about this piston marked red? If so it's not budging at all. I connected mains water and it didn't move. I put my finger on the outlet to build up pressure and still didn't move. It's rock solid.

Have you removed the switch ?

 

[mike 109444]

Where ever the pressure switch is, it will need to "cut out" the power feed to the pump motor so would/should be in the supply to the motor.

 

[rcx132]

Have you removed the switch ?

I removed the electrical switch.
If you click on the picture it opens a big picture so you can see close up.

 

[carbon]

Not had one of those apart but the pressure switch is operated by the white plastic pin that's in the centre of the red box. I have had a different model were the return spring has got weak and was unable to return the piston to the run position. To access the piston the metal frame has to be removed that clamps the unit together. Remove it with the pump uppermost to prevent the oil/ grease from escaping.
When the frame is off the detergent intake nipple needs to be removed. I find pull and slowly twist with a strong pair of pliers works, but be careful not to brake the small hose tail off. With that removed the piston can be pushed out from the back to access the spring. The o ring on the piston can drag and need some lubrication but never had any real success with that as the water flushes that away

 

[the snooper]

Check which direction the switch is in the off I suspect the piston is forced out but the return spring will be strong ish so it doesn't switch off during use

 

[The_Yellow_Ardvark]

Had it tonight.
Mine has the big 50mm on/of switch on the side. Turn it and should work, mine did not.

Opened it up the cam to press the toggle to allow the power though had rounded of. So sometimes it would or would not.

Waiting on the JB weld to cure.

 

[rcx132]

So I'll have to power it up and see if the pump pressure actuates the piston.

This is getting to be alot of effort considering a complete new body is £40. But these things seem to personally challenge me.

 

[The_Yellow_Ardvark]

The JB weld worked.
The switch cam now engages and the pump works.

 

[Fintray]

I think when it reaches a high pressure (above normal working) the switch cuts out the power supply, when you pull the trigger the pressure drops and the pressure switch closes to restore the power supply.

 

[the snooper]

It has to work with both in a way.

It has to sense the drop in pressure when you pull the trigger (trigger is just a valve in the handle) to turn on the pump motor, then it has to sense overpressure to turn the motor off when you release the trigger...

If it only worked on pump pressure, what tells it to turn on?

lack of it

 

[carbon]

These things should always be on with the main switch turned on unless the trigger is closed (pressure above operating pressure). The return spring in the pressure switch should have enough pressure in it to return the pressure switch to the run position but sometimes they don't. Had the misfortune to work on a HD605 in December, there choice of materials for the similar thing on that machine is stainless steel valve assembly in an aluminum housing, well and truly stuck together no chance of the return spring moving it.