Karcher K 3.91 M User Manual

K 3.91 M

English 2
Español 18
Français 35

5.961-806.0 03/06

HIGH PRESSURE WASHER OPERATOR MANUAL

MODEL OVERVIEW 3
IMPORTANT SAFETY INSTRUC-

TIONS
ASSEMBLY INSTRUCTIONS 6
OPERATING INSTRUCTIONS 7, 8
USING THE ACCESSORIES 8
WORKING WITH DETERGENTS 9
TAKING A BREAK 10
SHUTTING DOWN & CLEAN-UP 10
WINTERIZING AND LONG-TERM
STORAGE
CARE AND MAINTENANCE IN-

STRUCTIONS
CLEANING TIPS 12, 13
OPTIONAL CLEANING ACCESSO-

RIES
TROUBLESHOOTING 16, 17

4, 5

11

11

14, 15

Specifications

Max. Pressure 1700 PSI
Water volume 1.5 GPM
Amp draw 13 AMPS
Voltage 120 V
Part No. 1.636-902.0
Serial no.

Kärcher Customer Support USA

Call: 1-800-537-4129 for help or visit
our website:

www.karcher-usa.com/home

Please take a moment to register your
pressure washer online at

www.karcher-usa.com/warranty

Kärcher Customer Service CDN

Call: 1-800-465-4980 for help or visit
our website:

www.karcher-canada.com

Kärcher Customer Support

Mexico

Call: 01-800-024-13-13 for help or visit
our website: www.karcher.com.mx

Safety Alert Symbols

 DANGER

indicates “an imminently hazardous sit­uation which, if not avoided, will result in
death or serious injury.”

 WARNING

indicates “a potentially hazardous situa­tion which, if not avoided, could result in
death or injury.”

 CAUTION

indicates “a potentially hazardous situa­tion which, if not avoided, may result in
minor or moderate injury or in property
damage incidents.”

Owner/User Responsibility

The owner and/or user must have an
understanding of the manufacturer’s
operating instructions and warnings be­fore using this pressure washer.
Warning information should be empha­sized and understood.
If the operator is not fluent in English,
the manufacturer’s instructions and
warnings shall be read to and discussed
with the operator in the operator’s native
language by the purchaser/owner, mak­ing sure that the operator comprehends
its contents.
Owner and/or user must study and
maintain for future reference the manu­facturers’ instructions.

2 English

MODEL OVERVIEW

1 Power cord with Ground Fault Circuit

Interrupter (GFCI)

2 Water inlet with garden hose con-

nector
3 High pressure outlet
4 ON/OFF switch
5 Detergent tank (removeable)
6 Cap with detergent suction tube
7 High pressure hose storage
8 Trigger gun storage
9 Transport handle
10 Accessory storage
11 High pressure hose

12 Trigger

gun
13 Trigger gun safety lock
14 Vario Power Spray wand
15 Dirtblaster® (Rotating spray wand)

 CAUTION

This unit has been designed for use with
cleaning detergents recommended by
the manufacturer. The use of other
cleaning detergents may affect the op­eration of the machine and void the war­ranty.

For household use only!

English 3

IMPORTANT SAFETY INSTRUCTIONS

WARNING!

When using this product basic
precautions should always be

followed, including the following:

! Read all the instructions before us-

ing the product.

! To reduce the risk of injury, close su-

pervision is necessary when a prod­uct is used near children.

! Know how to stop the product and

bleed pressures quickly. Be thor­oughly familiar with the controls.

! Stay alert – watch what you are do-

ing.

! Do not operate the product when fa-

tigued or under the influence of alco­hol or drugs.

! Keep operating area clear of all per-

sons.

! Do not overreach or stand on unsta-

ble support. Keep good footing and
balance at all times.

! Follow the maintenance instructions

specified in the manual.

! This Product Is Provided With A

Ground Fault Circuit Interrupter Built
Into The Power Cord Plug. If Re­placement Of The Plug Or Cord Is
Needed, Use Only Identical Re­placement Parts.

! Risk of Injection or Injury – Do Not

Direct Discharge Stream At Per­sons.

! High pressure jets can be dangerous

if misused. The jet must not be di­rected at persons, animals, electrical
devices, or the machine itself.

! Wear safety goggles.
! Do not use acids and solvents in this

product. These products can cause

physical injuries to the operator and
irreversible damage to the machine.

! To reduce the risk of electrocution,

keep all connections dry and off the
ground. Do not touch plug with wet
hands.

! The Trigger Gun Safety Lock PRE-

VENTS the trigger from accidentally
being engaged. This safety feature
DOES NOT lock trigger in the ON
position.

! Do not use extension cord with this

unit.

GROUNDING INSTRUCTIONS

This product must be grounded. If it
should malfunction or breakdown,
grounding provides a path of least resis­tance for electric current to reduce the
risk of electric shock. This product is
equipped with a cord having an equip­ment-grounding conductor and a
grounding plug. The plug must be
plugged into an appropriate outlet that is
properly installed and grounded in ac­cordance with all local codes and ordi­nances.

 DANGER

Improper connection of the equipment­grounding conductor can result in a risk
of electrocution. Check with a qualified
electrician or service personnel if you
are in doubt as to whether the outlet is
properly grounded. Do not modify the
plug provided with the product - if it will
not fit the outlet, have a proper outlet in­stalled by a qualified electrician. Do not
use any type of adapter with this prod­uct.

4 English

GROUND FAULT CIRCUIT IN-

TERRUPTER PROTECTION

This product is supplied with a Ground
Fault Circuit Interrupter (GFCI) built into
the power cord plug. This device pro­vides additional protection from the risk
of electric shock. If power is interrupted
in the line, the GFCI will automatically
re-close the circuit to the load after pow­er is restored. Depending on the GFCI
model, it may be necessary to manually
operate the reset button to restore pow­er to the GFCI load circuit. If replace­ment of the plug or cord is needed use
identical replacement parts.

WATER SUPPLY

(Cold Water Only)

 CAUTION

When connecting the water inlet to the
water supply mains, local regulations of
your water company must be observed.
In some areas the unit must not be con­nected directly to the public drinking wa­ter supply. This is to ensure that there is
no feedback of chemicals into the water

supply. Direct connection via a receiver
tank or backflow preventer, for example,
is permitted.
Dirt in the feed water will damage the
unit. To avoid this risk, we recommend
fitting a water filter.

! Garden hose must be at least 5/8

inch in diameter.

! Flow rate of water supply must not

fall below 2 GPM (gallons per

minute).

! Flow rate can be determined by run-

ning the water for one minute into an

empty 5-gallon container.

! The water supply temperature must

not exceed 104°F/40°C.

! Never use the pressure washer to

draw in water contaminated with sol-

vents, e.g. paint thinners, gasoline,

oil, etc.

! Always prevent debris from being

drawn into the unit by using a clean

water source.

SAVE THESE
INSTRUCTIONS!!

ASSEMBLY INSTRUCTIONS

Required tools

A Philips Screwdriver, medium size

(not supplied)
for final assembling the unit.

B Screwdriver, small size (not sup-

plied)
for connecting high pressure hose

and trigger gun.

" STEP 1:

Stick the detergent suction tube with

cap on the fitting.

English 5

"

STEP 2:

Attach storage for high pressure
hose and secure with 2 screws

" STEP 5:

Place detergent tank into compart­ment and attach cap with detergent
suction tube.

" STEP 3:

Attach the handle and secure with 2
screws.

" STEP 4:

Attach trigger gun storage to handle.

" STEP 6:

Mount net to the backside of the unit
and place the accessory in it.

" STEP 7:

Attach the high pressure hose to the
trigger gun. Pull out the locking slide
from the right side of the trigger gun
handle (A), and insert the small end
of the high pressure hose into place
(B). Push the locking slide back into
the trigger gun to lock the hose in po­sition (C).

6 English

OPERATING INSTRUCTIONS

" STEP 1:

Connect the high pressure hose to
the unit’s high pressure outlet.

" STEP 2:

Insert the spray wand of your choice
into the trigger gun. Press in against
the spring tension and twist into
locked position.

" STEP 5:

Plug the Ground Fault Circuit Inter-

rupter (GFCI) into a receptacle.

Press RESET button, indicator

should be “ON”.

Press TEST button, indicator should

be “OFF”.

Press RESET button for use.

 WARNING

Do not use if above test fails.

" STEP 3:

Connect garden hose to unit’s water
inlet.

" STEP 4:

Connect garden hose to the cold wa­ter source and turn water on com­pletely.

" STEP 6:

Unlock the trigger gun safety lock.

Trigger the gun to eliminate trapped

air, wait for a steady flow of water to

emerge from the spray nozzle.

English 7

"

STEP 7:

Turn on the high pressure washer
(I).

The motor starts only if the trigger
of the gun is pulled and shuts off
when the trigger is released.

USING THE ACCESSORIES

 WARNING

To avoid serious injury never point
spray nozzle at yourself, other per­sons or animals.

Vario Power Spray Wand

! The Vario Power Spray Wand allows

you to adjust the cleaning pressure.
To clean at maximum pressure, the

wand must be positioned to the high
pressure setting (Max).

For lower pressure turn the wand
collar in the minus (Min) direction.
To apply detergent, the wand must
be positioned to the lower pressure
setting (Min).

Dirtblaster®

! This nozzle features a 0º pencil jet

which rotates 360º for maximum dirt
cutting action, effectively increasing
cleaning performance up to 50%.
This nozzle combines the cleaning
performance of a 0º pencil jet with
the surface coverage of a wide angle
nozzle.

Not recommended for soft materi­als, siding, painted surfaces,
decks or autos.

! Always test an inconspicuous area

before cleaning with the Dirtblaster

8 English

WORKING WITH DETERGENTS

Detergents can only be applied at
low pressure (Min.).

" STEP 1:

Install the Vario Power Spray Wand.
Set the spray wand to the low pres­sure setting (Min.).

" STEP 2:

Fill the Detergent Tank with the se­lected Ready To Use detergent.

" STEP 3:

Turn on the pressure washer (I). Pull
trigger to operate unit: Liquid deter­gent is drawn into the unit and mixed
with water. Apply detergent to work
area. Do not allow detergent to dry
on surface.

" STEP 5:

Cleaning up: Always draw fresh wa-

ter through the detergent tank when

done to flush any remaining deter-

gents from the injection system.

For best results see Cleaning Tips
for specific information on how to
clean different surfaces.

Always Use Kärcher Detergent for
Best Results

Kärcher biodegradable detergents are
specially formulated to protect the envi­ronment and your pressure washer. The
special formula won’t clog the suction
tube filter and will protect the internal
parts of the pressure washer for a long­er life. For Kärcher Detergents, check
your retailer or visit our website:

www.karcher-usa.com/home

The following Kärcher detergents are
available:

One Gallon ready to use

! All Purpose & Vehicle Cleaner
! Deck & Patio Cleaner
! Heavy Duty Degreaser
! Exterior House Cleaner

 CAUTION

Never use:
– Bleach, Chlorine products and other

corrosive chemicals
– Liquids containing solvents (i.e.,

paint thinners, gasoline, oils)
– Tri-sodium phosphate products
– Ammonia products
– Acid-based products
These chemicals will harm the unit and
will damage the surface being cleaned.

Use of these items will void the war­ranty.

English 9

TAKING A BREAK ..five minutes or more

" STEP 1:

Release trigger and engage gun
safety lock.

" STEP 2:

Turn pressure washer to OFF (O)
position.

SHUTTING DOWN & CLEAN-UP

" STEP 1:

Turn the switch to OFF (0) position
and unplug cord from outlet.

" STEP 2:

Turn off the water source.

" STEP 3:

Press trigger to release water pres­sure.

" STEP 5:

Disconnect the high pressure hose
from the high pressure outlet.

3

2

" STEP 4:

Disconnect the garden hose from
the water inlet on the unit.

10 English

" STEP 6:

Release trigger and engage gun
safety lock.

B

A

WINTERIZING AND LONG-TERM STORAGE

" 1: Disconnect all water connections.
" 2: Turn on the machine for a few

seconds, until the water which had
remained in the pump exits, turn off
immediately.

" 3: Do not allow high pressure hose

to become kinked.

" 4: Store the machine and accesso-

ries in a room which does not reach
freezing temperatures. DO NOT

of heat as it may dry out the pump

seals.

 CAUTION

Failure to follow the above directions
will result in damage to the pump as­sembly and accessories.
Kärcher also recommends the regular
practice of using a pump protector like
“Kärcher Pump Guard” to help during
storage in the winter months.

store near furnace or other sources

CARE AND MAINTENANCE INSTRUCTIONS

Cleaning the water inlet filter Maintenance

" STEP 1:

Pull out washer from the water inlet.

" STEP 2:

Pull out water inlet filter with flat­nose pliers.

The unit is maintenance-free.

" STEP 3:

Rinse out water inlet filter in warm
water.

" STEP 4:

Reinsert water inlet filter and washer
into the water inlet.

English 11

CLEANING TIPS

Deck Cleaning

(with or without detergent). Pre-rinse

deck and surrounding area with fresh
water. If using Kärcher Deck Wash, ap­ply to surface at low pressure. For best
results, limit your work area to smaller
sections of approximately 25 square
feet. Allow Deck Wash to remain on sur­face 1-3 minutes. Do not allow deter­gent to dry on surface. Rinse at high
pressure in a long sweeping motion
keeping the spray nozzle approximately
3-6 inches from the cleaning surface.
Always clean from top to bottom and
from left to right. When moving on to a
new section of the cleaning surface, be
sure to overlap the previous section to
eliminate stop marks and ensure a more
even cleaning result.

House Siding

(with or without detergent). Pre-rinse

cleaning surface with fresh water. If us­ing Kärcher Pressure Wash, apply to
surface at low pressure (for best results,
limit your work area to sections of ap­proximately 6 feet and always apply de­tergent from bottom to top). Allow
Pressure Wash to remain on surface 1­3 minutes. Do not allow detergent to dry
on surface, if surface appears to be dry­ing, simply wet down surface with fresh
water. If needed, use special wash
brush attachment (not included) to re­move stubborn dirt. Rinse at high pres­sure from top to bottom in an even
sweeping motion keeping the spray
nozzle approximately 6 inches from the
cleaning surface.

Cement Patios, Brick and Stone

(with or without detergent). Pre-rinse

cleaning surface with fresh water. If us­ing Kärcher Pressure Wash or Degreas­er, apply to surface at low pressure. For
best results, limit your work area to
smaller sections of approximately 25
square feet. Allow Pressure Wash or
Degreaser to remain on surface 1-3
minutes. Do not allow detergent to dry
on surface. Rinse at high pressure in a
sweeping motion keeping the spray
nozzle approximately 3-6 inches from
the cleaning surface. Always clean from
top to bottom and from left to right. For
removing extremely stubborn stains,
use the Dirtblaster Nozzle.

Cars, Boats & Motorcycles

(with or without detergent). Pre-rinse

vehicle with fresh water. If using Kärch­er Touchless Vehicle Wash, apply to
surface at low pressure. For best re­sults, clean one side of vehicle at a time
and always apply detergent from bottom
to top, do not allow detergent to dry on
surface. If needed, use special wash
brush attachment (not included) to re­move stubborn dirt. Rinse at high pres­sure in a sweeping motion keeping the
spray nozzle approximately 6-8 inches
from the cleaning surface (distance
should increase when rinsing pin-strip­ing or other sensitive surfaces). Always
clean from top to bottom and from left to
right. For best results, wipe surface dry
with a chamois or soft dry cloth.

12 English

Barbecue Grills, Outdoor Power

Equipment & Gardening Tools

(with or without detergent). Pre-rinse

cleaning surface with fresh water. If us­ing Kärcher Pressure Wash or Degreas­er, apply detergent at low pressure.
Allow Pressure Wash to remain on sur­face 1-3 minutes. Do not allow deter­gent to dry on surface. Rinse at high
pressure keeping the spray nozzle ap­proximately 3-6 inches from the clean­ing surface. For removing extremely
stubborn dirt, it may be necessary to
move the spray nozzle even closer to
the surface for greater dirt cutting ac­tion.

Patio & Lawn Furniture

(with or without detergent). Pre-rinse

furniture and surrounding area with
fresh water. If using Pressure Wash, ap­ply to surface at low pressure. Allow
Pressure Wash to remain on surface 1­3 minutes. Do not allow detergent to dry
on surface. If needed use special Wash
Brush Attachment (not included) to re­move stubborn dirt. Rinse at high pres­sure in a sweeping motion keeping the
spray nozzle approximately 3-6 inches
from the cleaning surface. For best re­sults, clean from top to bottom and from
left to right.

pressure washer may remove the

loose paint from the surface.

! When using on surfaces which might

come in contact with food, flush sur-

faces with plenty of drinking water.

! For additional cleaning tips, visit our

website at www.karcher-usa.com/

home

Recommendations

! Before cleaning any surface an in-

conspicuous area should be cleaned
to test spray pattern and distance for
maximum cleaning results.

! If painted surfaces are peeling or

chipping, use extreme caution as

English 13

OPTIONAL CLEANING ACCESSORIES

Optional accessories are available to
further enhance your cleaning capabili­ties. These accessories are accurate as
of the printing date of this manual.
Please check our website www.karch­er-usa.com/home for pricing and up-to­date information.

Pump Guard

Specially formulated to protect your
pressure washer from freezing, corro­sion and premature wear. The Pump
Guard also adds lubrication to valves
and seals to prevent sticking. Highly
recommended for all Karcher pressure
washers!

Part No. 9.558-998.0

Water Pumping Kit

Attach this accessory to your pressure
washer to quickly pump large quantities
of water out of a standing source, such
as a barrel or bucket. Fits most Karcher
pressure washers up to 2300 PSI.

Part No. 2.637-214.0

your pressure washer by up to 66" with
this extension kit. Includes 4 aluminum
sections for variable length. 66" fully as­sembled. Fits most Karcher pressure
washers up to 2300 PSI. (bayonet)

Part No. 2.640-746.0

Rotating Wash Brush (bayonet)

For more effortless cleaning of all
smooth surfaces (painted, glass and
plastic) try Karcher's Rotating Wash
Brush. Use it on your automobile, house
siding or windows. The water pressure
from your pressure washer causes the
inner brushes to gently spin, making
your cleaning job much easier. The an­gle of brush head is adjustable to help
you reach difficult areas. Excellent for
the application of detergent. A must­have accessory designed for Karcher
pressure washers up to 2300 PSI. (bay­onet)

Part No. 2.640-743.0

Soft Clean Washing Brush

25 Ft. Extension /Replacement

High-Pressure Hose

Replacement hose fits Kärcher pres­sure washer with screw-on type gun
connections from 2400psi to 2500psi,
Extension Hose for all Kärcher high
pressure washers between the original
equipment hose and machine up to
2500 psi.

Part No. 2.640-850.0

66" Extension Wand (Four piece)

Need to clean second story windows or
other high areas? Increase the reach of

14 English

Made with soft bristles that will not harm
painted surfaces. Easily attaches direct­ly to the trigger gun. Ideal for stubborn
dirt on cars, boats, patio furniture and
other surfaces. Great for applying deter­gent. Fits most Karcher pressure wash­ers up to 2300 PSI. (bayonet)

Part No. 2.640-740.0

25 ft. Pipe Cleaning Kit (bayonet)

Need to clean blocked pipes, drains or
downspouts? Karcher's pipe cleaning
kit is the answer! The pipe cleaner pro­pels itself forward while simultaneously
flushing out debris. For example, insert

the cleaning nozzle in the base of a
downspout, pull the trigger on the pres­sure washer gun and watch as the noz­zle shoots out leaves and other debris
while climbing upward. Connects direct­ly to the trigger gun of most Karcher
pressure washers up to 2300 PSI. (bay­onet)

Part No. 2.640-747.0

Wet Sandblasting Kit (bayonet)

Why spend hours stripping old paint and
rust by hand using harsh chemicals?
Let Karcher's Wet Sandblasting Kit do
the work! Attach the kit to your pressure
washer, add abrasive material and at­tack the rust and paint with our eco­friendly alternative. Fits most Karcher
pressure washers up to 2300 PSI. (bay­onet)

Part No. 2.638-792.0

Detergent Foamer Attachment

T 100 Wide Area Surface Cleaner

For cleaning surfaces such as patios,
terraces and driveways without splash­back, there is no better solution than
Karcher's T 100. It saves time by clean­ing a one foot wide area gently as it hov­ers, providing consistent, streak-free
cleaning. When you finish cleaning the
patio and driveway, remove the wand
and use the handle to clean garage
doors and other vertical surfaces. In­cludes two nozzles which spin at high
speed for optimum results. Our top sell­ing accessory for Karcher pressure
washers up to 2300 PSI. (bayonet)

Part No. 2.640-959.0

Ideal for applications which require a
thick foam. Simply fill the resevoir cup
with liquid pressure washer detergent to
generate a foam spray. Connects di­rectly to the trigger gun. Fits most
Karcher pressure washers up to 2300
PSI. (bayonet)

Part No. 6.964-507.0

English 15

TROUBLESHOOTING

 CAUTION

Symptom Cause Solution

Motor will not start On/Off switch is in the “OFF”

(O) position.
Power cord is not plugged in. Plug in power cord.
Electrical outlet does not sup-

ply adequate power.
Tripped GFCI plug. Press “RESET” button on

Tripped circuit breaker. Switch off pressure washer.

Unit does not
reach high pres­sure.

Output pressure
varies high and
low.

Diameter of garden hose is
too small.

Water supply is restricted. Check garden hose for kinks,

Not enough inlet water sup­ply.
Water inlet filter is clogged. Remove filter and rinse out in

Spray wand is on low pres­sure position.

Not enough inlet water sup­ply.

Pump is sucking air. Check that hoses and fittings

Water inlet filter is clogged. Remove filter and rinse out in

Discharge nozzle is obstruct­ed.

Calcified gun, hose or spray
wand.

Disconnect the machine from the power
source before making any repair.

Turn switch to the “ON” (I) posi­tion

Try a different outlet.

GFCI plug.

The reset comes automatically
once the temperature of the
unit drops.
Replace with a 5/8 inch or larg­er garden hose.

leaks and blockage.
Open water source full force.

warm water.
Turn spray wand to high pres-

sure position.
Turn water on full force. Check

garden hose for kinks, leaks or
blockage.

are air tight. Turn off machine
and purge pump by squeezing
trigger gun until a steady flow
of water emerges through the
nozzle.

warm water.
Blow out or remove debris with

a fine needle.
Run distilled vinegar through

detergent suction tube.

16 English