My Karcher K9.8 electric pressure washer started

Sounds like its shot. You can probably buy a replacmentnoff Ebay at a low price.

If you have a Karcher then you should always post your machines barcode.

Because you have the low pressure and pulse this will be the valve block. Your machine has 3 piston and each has 2 valves (inlet and outlet). Because you dont have the barcode, i cant be sure if you will buy a valve kit of 6 valves or a pre-assembled manifold block.

it could be this machine and spares :
http://www.sparesgiant.com/cleaning-equipment/pressure-washers/karcher/k-series-parts/k2-range/k2-36m16724300/

The karcher barcode is on a silver sticker and is usually 15 digits long. Example 156987400000123 is actually model 1.569-874.0 and serial number 00123....

you will have to take the cover off & look for melted wires or a fuse.
if there is no fuse the capacitor may have been cooked.
it should be a white cylinder.if it has been damaged it will have burn marks and may be swollen.
replace the capacitor and it should start.

water is pouring out of my 5 year old karcher from the trigger handle WHY???

Hi:
The first thing i would do is be sure there is not a partial blockage in the nozzle.

It sounds like you have cracked part inside. Parts availability depends on were you live???

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.

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

here is a troubleshooting link for Karcher products

http://www.the-power-washer-advisor.com/electric-pressure-washer-troubleshooting.html

see www.pressureparts.com for karcher