Question about Karcher 2500 PSI Pressure Washer

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My Karcher 2500 PSI won't give me any pressure when I squeeze the trigger. Do you know what I can do to fix it.

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Hi and welcome to FixYa, I am Kelly
The list below is from over 40 years of experience.

List of things to do:

1. First off check the screen where the hose connection connects to the unit for debris. Most of time these are plastic screens.
2. Add 2 - 3 ounces of oil into the pump water inlet connection. On upright units it is nearly impossible to do this without a SHORT hose that you can pour oil into that has the male end on it.
Pull the recoil through ignition off or very slow until your sure there is oil exiting the high pressure side of the pump. Leave the Short hose elevated and let it sit over night.
3. Next day first thing pull the recoil through about 3 times slow. Attempt normal use but bleed all the air out of the water supply hose before making the connection to the pump. WATER ON, Squeeze the wand trigger and let all of the air out of the high pressure hose and wand.
4. Start the unit and let it run for about 1 min before squeezing the wand trigger. Squeeze the trigger about every 10 seconds and release. If at this point pressure is starting to increase cycle the wand trigger in half second intervals. (What your doing is attempting to force the bypass un-loader valve to move inside the pump.)
5. If this does not work.... you will have to remove the bypass un-loader valve (Big Knob with locking nut device on the output side of the pump. Carefully remove it so as not to cut the seals. I like to use a couple of drops dish-washing soap for removal. Wipe off / clean the springs and seals. Clean the inside of the pump housing really well. Feel it with your fingers... no rough surfaces in seal area. If you find rough surfaces use at least a 220 grit sand paper by rolling it up and sticking it into the hole for sanding the surfaces. Wipe everything clean. Inspect all seals for tears of cuts (None allowed..replace bad seals) Use WHITE GREASE on the housing seals and springs for assembly. Don't be afraid to use a liberal amount. Assemble and then test following step 3 and 4 above.

This brings about 85 % of them back to life without changing any seals or doing piston work on the pump. The unloader valve sticks most of the time due to either corrosion or debris with the end result of no high pressure. .

Thanks for choosing FixYa,

Posted on May 19, 2011


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Posted on Jan 02, 2017


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