Need installation instructions for suction tube

Probably pickup is plugged, try (with safety goggles on) blowing back through the pickup tube.

Perhaps you contact the firm where you bought this? they should be able to help you in the first place.
Or perhaps even Karcher can help on their website? Worldwide Customer Service

there should be a ball check valve in the soap suction hose lets soap in keep water out poke a paper clip in the hole a few times soap will build up there and make the ball valve leak

Check the suction line for leaks. It needs constant water
supply to build a constant water pressure. You may also
check the pressure regulator for leaks. You may also
check the carbide or ceramic pistons for breaks. Send you e-mail for further assistance.

It must be set on NO pressure. If it has exchangeable tips, it is the black one. If the end of the soap tube looks like THIS, (#5) you may need to twist it to open it

Dear johnny_river,
In general there are many causes why soap is not sucked. In a domestic and various other machines the soap is only sucked in low pressure. So one thing you can try is remove the nozzle or the complete lance from your gun. This will give a low pressure. If you attach a pipe directly to the machine soap inlet, and soap is not sucked, than the soap valve is "stuck closed" with soap. It is important that one must work with fresh water after using soap. This to flash the system from any soap left. So in a few words attach a pipe directly to the nipple at the machine and use low pressure. Important , you do not have to use soap to test....use fresh water. If this works( which it should)...than service the flow control tap or change it altogether.
Regards,
fulltech.

Here is the offical link to manuals and warranty cards for the residential models of Karcher Pressure Washers
.
http://www.karcherresidential.com/us/Service/usermanuals.htm

Hi, I work in the italian factory of Karcher. In my opinion the problem is caused by the breaking of the collector. This is a black component of plastic where is inserted the detergent suction valve and the safety valve. To replace this component you have to go in a repair center Karcher.

Dear Pgarciax,
It is important that you must have mentioned the model number of your Karcher. Just the same I can surely say that your machine's fault lies in the "SPILL VALVE"
When the gun is open and pressure is being produced, the spill valve is in a relaxed position. Also it has at the bottom a valve, which when pressure is produced it is closed. If this does not close due to dirt or corrosion, the pessure goes down. Now when you close the gun,pressure forces the spill valve down to close the electrical system. Now if the "o" rings of the spill valve are damaged, the machine will start going on and off while in stand-by. So if you know how to locate the Spill Valve, all one has to do is change it with a new one.
In some Karcher machines there are 2 spill valves. One regulates pressure and the other one is for switching off the machine when the gun is closed.
Low pressure could also be due to faulty suction or delivery valves. Most probably the suction valves.
But when saying that there are short interruptions while in stand by, I stick to the fact that the spill valve needs renewing.
Regards,
MG.

If there is a check valve in the little line that you put into your soap tank, it doesn't need primed. I have very large 5000 psi units and have enough suction without one. If you can't get it going, you can always remove the hose end near the pressure washer end and fill it by immersing the tubing in the soap, but that shouldn't be necessary. Sometimes the little fitting with the check valve in the bottom get plugged up as well, so that might be your problem. Hope this helps you, Rick