The discharge pressure on my Karcher electric pressure cleaner varies. When low no cleaning can take place. How can I fix?

SOURCE: Karcher electric pressure washer

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.

SOURCE: Karcher K 3.68M Electric Pressure Washer. Wand trigger Locks Up.

Sounds like the pressure valve is broken thats why you cant depress the trigger , the valve is on the pump , i would suggest taking it to a repair shop as they are fiddly things to fix

SOURCE: Karcher K 2400 HH Pressure Washer no pressure

http://www.landanorthwest.com/documents/instructional/spill_valve_instructions.pdf

SOURCE: Unloader Valve - Karcher Pressure Washer

where is the unloader valve locaed on a Briggs Stratton pressure washer?

SOURCE: I have karcher 620m pressure

Try this. While pushing the trigger of the gun, turn lance fully anticlockwise and then turn back fully clockwise.