My Karcher K3.48M pressure washer remains in the low pressure mode even when I return the pressure nozzle to the high pressure position. How can this be corrected. The pump seems to build up the pressure because when I release the handle the pump motor stops. This is a fairly new pump which was purchased in the latter part of last year(2010). Could this have been caused by the detergent I have been using which is an automotive shampoo? Please help I love this washer and for the times that I used it, it perfectly satisfied my needs.

SOURCE: I was using the pressure washer and it stopped

This problem, where the unit continually switches on and off when the handgun is closed, is quite common. Unfortunately it has at least six different possible causes, only two of which are easily checked. 
The first thing you can do is look for leaks.  Even the slightest leak will cause this pulsing because the unit gets up to pressure, switches off, loses pressure, switches back on again, comes back up to pressure, switches off... and so on.  This repeated switching is not good for the motor and should not be allowed to continue for longer than necessary to observe what's happening.
So... 1. Does the handgun shut off completely, or does it drip? If it drips, it may simply be because a seal has failed. The handgun can be dismantled, checked, and any defective parts replaced; be sure to lubricate O-rings with silicone grease when reassembling. As a last resort, the whole gun may need to be replaced.
2. Are there any visible leaks at the high-pressure hose screw connections?  If so, most likely an O-ring needs replacing - again lubricate the new one well with silicone grease.
3. If there are no visible leaks, either from the gun or from the connections, all other possible causes are internal within the cylinder head or control head of the pump. New parts will be needed and this normally calls for a professional repair, although it's not beyond the scope of a truly competent amateur.
I hope this helps. Any further questions, just ask! Please remember to rate this response.

SOURCE: Karcher G 3000 BH Engine Pumping Problem

This may not be a motor problem. It sounds like your pump is not working properly and the motor is just following the pump. First thing to do is check for leaks in the pump, wand hose, gun etc. It may also be a blown water seal inside the pump.

Jim Goldsmith

• 2005 Answers
• Posted on Aug 31, 2009

SOURCE: new Karcher pressure washer won't start

replace the fuel carburetor filter and, or, your fuel tank filter

SOURCE: I am trying to clean my block paving using my

Hello Sue, you don't say where in the world you live, but if you are attempting to clean dirt and algae off pavers, you need to add a solution to the water jet via the inbuilt attachment. Mix a fairly mild solution of bleach and detergent, pus a dash or deodoriser to the cantainer. Put your karcher on low pressure and give all the blocks a good wetting. Do this in the morning so the solution doesn't dry. After 20 ~30 mins, Claen off with the Karcher on normal high pressure (not the tubo lance). HINT: Leave the trigger on all the time and don't stop and start using it. This will prevent hayraulic hammer which can split the pump head.

Testimonial: "Thank you for your speedy response and advice. I will certainly give it a try. Sue,from West Mids, UK"

Kelly

• 3740 Answers
• Posted on Apr 18, 2010

SOURCE: I can use my Karcher K3 jet wash as long as i hold trigger down

Most pressure washers have ball lock type fittings on the hose connections. What happens is the little steel balls get a bit of corrosion and do not lock the male fitting properly with the female coupling. Load up the fitting with some Oil or WD 40. Then connect and disconnect the fitting several times to losen up the balls and springs. Should the spring in the coupling break you will get the exact symptom your describing.

If the OIL / WD 40 does not do the trick then you may have to change out the quick disconnect coupling.

Kelly