I have a Karcher 3.99 Pressure Washer. The motor appears to be working and water is passing through the machine when turned to the detergent application setting. However when the lance is tightened to turn on the pressure, no water is coming through. The Karcher is just over 1 year old David

Firstly make sure the pressure set valve is turned the right way, fully anticlockwise I think.(if it has one I could be thinking of the next model up) and that the lance nozzle is in the correct position not set to detergent or mid point between positions. If that is ok it is probably the switch at the bottom of the machine. If under warranty send it back karcher switches are not good.

This fault is within the control head, under the detergent valve is a small spring loaded valve that acts to induce the detergent, this will have failed, the shaft of the component breaks off the disk base leaving a small hole in the centre of the disk. This is enough to allow pressure past the component. The machine will pulse when operated and will not induce the detergent. I've looked everywhere to find this part as I have a karcher with the same fault.

I have a john deere 3000psi pressure washer with similar problem. Running fine then a puff of smoke and it shut down. I checked the oil and found it full of water. Not only that but since I still had the water turned on, the water was flowing out of the dip stick tube. I'm trying to find a solution online and will pass any information on.

Good news, your engine runs
But your pump may be bad

Here's how to test your pump
Check oil as outlined lower down
Disconnect the washer hose and gun
Connect water hose and turn on water and water should pass straight through the pump
Look for clogs in the hose-end where water hose connects to machine

Turn on machine and see if water shoots out pump
If water shoots out of pump, but no water shoots out of gun, then you may have a 'mud-dobber' wasp clog in your washer line or gun

Look for clogs in the end of each water connection.
Now connect washer hose without the gun, tun on the machine, and see if water shoots out of washer hose
Finally, the gun trigger mechanism may be bad
I don't know which gun you have ... but we replaced guns on our machine now-and-then ... google-search power washer guns for a replacement

Check your pump oil
Pump oil is SAE20 or SAE30 non-detergent motor oil
Pump should be no more than 1/2 full of oil
Use plastic hose to drain pump oil
Do not turn machine on its side or turn machine over or engine oil will run into carburetor

if the machine is blowing fuses then it could be the motor! if not then maby the start cupasitor has failed

Before you start it up:
1. Disconnect the high pressure hose 2. Connect the water supply and turn on 3. Make sure water is flowing through the pump
Start the motor, run for about 10 seconds and then turn off.
Turn off the water supply, connect the high pressure hose, turn water back on, start the motor and away you go.

Dear Carrie688,
I cannot for sure understand your problem. You say, you do not know how to WORK power washer. Does WORK mean FIX...or USE???? I will assume that you wish to know how to use it.
First without water connected and without gun connected...switch on the machine. If it turns, then this means the electric motor is OK. Now connect the hose and gun. Connect water supply. Now always start the machine with gun open. This will help to remove air from system. When pressure builts up, close gun, and machine must stop instantly. If machine does not stop, open the gun again and switch off the machine. If the machine continues working when the the gun is closed, this will result in a lot of damage. I do not know what model you have, because also there are old models that when gun is closed, the machine keeps running. I assume your model is recent. So the machine will stop when gun is closed. Now when finished, switch off machine and electricity. And most important release pressure from gun. Do not store machine with pressure still in it. This will damage machine and it is not safe.
Now if you have detergent, this can only work on low pressure. There are bigger machines that detergent works on high pressure. But the normal system is that detergent works on low pressure. Also before storing, pass fresh water to remove all detergent from pump of machine. Never store a machine with detergent in its system.
Regards,
Fulltech.

Dear Tigger82 (also montaver2000),
This explaination is relavent to various Karcher models, especialy your model. When you are using the machine with the gun open....presurised water comes out of the lance. When you close the gun, the machine stops. This happens by means of a Spill Valve or often called the Control Valve. When the gun is closed, this spill valve cotracts with built up pressure and at the same time works on a miro switch which cuts the electricity....and thus stops the electric motor. Now in many cases when the gun is again opened, this spill valve sticks and keeps the electric circuit closed.
In all cases you must open the cover, and locate this spill valve. Sometimes it is easy to see a micro switch on it. If you remove the miro switch from the spill valve the motor will for sure turn.
Now the spill valve gets stuck for many reasons. One of the reasons is that you leave the machine under pressure for a long time and even store away the machine with pressure still in the system. A spill valve also gets stuck due to detergent. I sometimes service the spill valve and lubricate with special solicon grease. But the best way is to change the spill valve with a new one. So in a few words, the spill valve is stuck and leaving the microswitch off. So the electric motor cannot turn. One final hint is that sometimes the spill valve is difficult to remove. So all one has to do is attach water supply and switch on the pump. With the pressure produced the spill valve will be pushed out. In my oponion this job must be done by a person who knows what he is doing. Carefull that you have safety electrical breakers. See that you have safety shoes, safety gloves and eye protection.
Regards,
Fulltech.

Dear mike husband,
One reasin for this fault could be a damaged lance or turbo lance. Try by replacing with new ones. If the problem is not solved, then the fault is due to a damaged spill valve. The spill valve could easily be damaged by using not suitable chemical or detergents. After using chemical detergents, one must always rinse the machine by passing pure water. The spill valve could also be damaged by leaving the machine for a long time with pressure in the system. One must never store such machines with pressure still inside. Always press the gun before storing.
Well the solution is to change the spill valve with a new one. In some cases even faulty suction valves can give this problem. But in the majority of cases it is the spill valve.
If you do not know how to fix this problem, it is better to be done by an expirienced technician.
Regards,
MG.

It will only pick up detergent if you use a low pressure detergent nozzle - or no nozzle at all. It also takes a while for the detergent to get to the nozzle.