Benchmark BW Series User manual

BW SERIES
MANUAL
TM

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TM
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Thanks for choosing the BW Series!
You're excited to get started, we'll keep this brief.
READ THIS ENTIRE GUIDE BEFORE USING THIS
PRODUCT AND SAVE FOR LATER USE.
This user guide contains important instructions including safety,
setup, operation, and maintenance that must be followed. All
information in this guide is based on information available at
the time of print. This guide or revised editions can be found on
our website for download. No part of this publication may be
reproduced without written permission.
THIS PRODUCT MEETS ALL CERTIFICATION REQUIREMENTS FROM:
The engine exhaust from this product contains chemicals known
to cause cancer, birth defects or other reproductive harm.
©2023 Benchmark. All Rights Reserved.
BW_Manual_EN_2023-04-13

TABLE OF CONTENTS
1. Safety 1
2. Learn About Your Pressure washer 5
3. Getting Started 7
3.1 Assembling the Handle 7
3.2 Prepare the Air Filter 8
3.3 Replace the Temporary Pump Oil Dipstick 9
3.4 Add Engine Oil 10
4. Pre-Operation Check 12
4.1 Check Pump Oil Level 12
4.2 Check the Fuel Level 13
4.3 Check the Cold Water Supply 14
4.4 Assemble the Spray Gun and Hoses 14
5. Using your Pressure washer 18
5.1 Starting Your Pressure Washer 19
5.2 Stopping the Engine 21
6. Using Your Pressure washer 22
6.1. Using the Spray Wand 22
6.2. Using Spray Nozzles 23
6.3 Working with Detergents 25
6.4 Pressure Regulator 27
6.5 Carburetor Modification for High Altitude Operation 28
7. Maintenance 30
7.1 Maintenance Schedule 31
7.2 Changing the Engine Oil 32
7.3 Changing the Pump Oil 34
7.4 Cleaning the Air-Filter 35
7.5 Nozzle Cleaning 36
7.6 Cleaning Water Inlet Filter 36
7.7 Spark Plug Service 36
7.8 Spark Arrester Maintenance 37
7.9 Fuel Filter Maintenance 37
7.10 Emission Control System 38
8. Transportation & Storage 40
9. Troubleshooting 43
10. Technical Specifications 45
11. Limited Warranty 46

1BW SERIES
1. SAFETY
DANGER!
Using a gas powered pressure washer indoors can kill you in
minutes.
The engine exhaust from this product contains chemicals known
to cause cancer, birth defects or other reproductive harm.
1.1 OPERATOR SAFETY
WARNING!
Always perform an oil, fuel and air lter check before starting the engine.
Properly clean and maintain the equipment.
Operate the pressure washer according to instructions for safe and
dependable service.
Before operating the pressure washer, read the user guide carefully.
Otherwise, it may result in personal injuries or equipment damage.
Never run the pressure washer in an enclosed area to avoid harm from
exhaust emissions of a poisonous carbon monoxide gas.
Be careful not to touch the exhaust system during operation due to risk
of burns.
Pay attention to the warning labels. The engine exhaust system will
become heated during operation and remain hot immediately after the
engine is stopped.
Gasoline is a highly ammable and explosive liquid. Refuel in a well
ventilated area with the engine stopped.
Use of gasoline with an ethanol content greater than 10% can damage
the engine and fuel system and will void the manufacturer’s warranty.
When refueling the pressure washer, keep it away from cigarettes, open

2
TM
ames, smoke and/or sparks.
Place the pressure washer at least 3 feet away from buildings or other
equipment during operation.
Run the pressure washer on a level surface. Tilting the pressure washer
may result in fuel spills.
Know how to stop the pressure washer quickly and understand
operation of all the controls. Never permit anyone to operate the
pressure washer without proper instructions.
Keep children, pets and machinery with rotating parts away during
operation.
Do not operate the pressure washer in rain or snow.
Do not touch the spark plug while the engine is operating or shortly after
the engine has been shut down.
Wear ear and eye protection while operating this unit.
1.2 USE SAFETY
WARNING!
NEVER direct the water spray towards electrical wiring, devices, or
directly at the pressure washer itself. Fatal electric shock may occur.
NEVER direct the water ow at people. The high pressure jet can be
dangerous if misused and must not be directed at people, animals,
electrical devices or the unit itself. DO NOT TREAT FLUID INJECTION
AS A SIMPLE CUT! Seek medical help immediately.
NEVER spray ammable liquids, risk of explosion. Operate only where
open ame or torch is permitted.
Always operate on dry, solid level ground.
DO NOT expose this product to excessive moisture, dust, or dirt.
DO NOT use in areas where fumes from paint solvents or ammable
liquids pose a potential hazard.
Inspect before each use, ensure all nuts, bolts, screws, hydraulic
ttings, hose clamps, wheels. etc. are securely tightened. Always check
the oil level before operating. Never operate when the product is in poor
mechanical condition.
Never move this product while spraying.
DO NOT run the engine at high speed when you are not using the
product.
DO NOT use acids, solvents, alkaline, or ammable substances in this
product. They may cause injuries to the operator and will permanently

3BW SERIES
damage the machine.
Only use detergents that are designed to be specically used with a
pressure washer. The use of other cleaning detergents may void the
warranty.
The spray gun will kick, hold with both hands.
Never run the unit dry, always be sure the water supply is turned on fully
before operating the unit.
Know how to stop the product and bleed pressure quickly. Be
thoroughly familiar with the controls.
DO NOT operate the pressure washer without the water turned on.
DO NOT overreach or stand on unstable surface. Keep good footing
and balance at all times.
Wear proper eye and ear protection while operating.
1.3 MAINTENANCE SAFETY
WARNING!
Turn off the engine before performing any maintenance. Failure to do so
can cause severe personal injury or death.
Before performing maintenance depressurize the unit by turning off the
water supply and squeezing the trigger of the spray wand until water
stops owing.
Use rubber gloves when coming into contact with engine oil.
After any maintenance is performed, wash immediately using soap and
clean water, repeated exposure to lubricant may cause skin irritation.
Do not clean the lter element with ammable liquids like gasoline, an
explosion may occur.
Allow the pressure washer set to cool down before performing any
maintenance.
Do not spray the pressure washer itself.
Always stop the pressure washer set before removing the oil ller cap.
Only qualied maintenance personnel with knowledge of fuels and
machinery hazards should perform maintenance procedures.
Do not let water in the pump freeze. See the storage section for further
details on how to store properly during the winter.
See ‘Maintenance Schedule’ for the recommended maintenance
schedule.

4
TM
1.4 OTHER SAFETY TIPS
WARNING!
Running engines give off carbon monoxide, an odourless poisonous gas
that can cause nausea, fainting, or death. Do not start engine indoors or
in an enclosed area even if the windows and doors are open.
If you start to feel sick, dizzy, or weak after the pressure washer has
been running, move to fresh air RIGHT AWAY. See a doctor. You could
have carbon monoxide poisoning.
Pressure washers vibrate in normal use. During and after the use of
the pressure washer, inspect the pressure washer as well as hoses
connected to it for damage resulting from vibration. Have damaged
items repaired or replaced as necessary. Do not use hoses that show
signs of damage such as broken or cracked insulation or damaged
connectors.
TOXIC FUMES HAZARD. Running engines give off
carbon monoxide, an odourless poisonous gas
that can cause nausea, fainting, or death. Do
not start engine indoors or in an enclosed area,
even if the windows and doors are open.
DANGER TOXIQUE. Faire fonctionner un moteur dégage de
l’oxyde de carbone, un gaz inodore toxique qui peut
provoquer la nausée, évanouissement ou la mort. Ne
démarrer pas le moteur à l’intérieur ou dans une espace clos,
meme si les fenêtres et les portes sont ouvertes.

5BW SERIES
2. LEARN ABOUT YOUR PRESSURE WASHER
This section will show you how to identify key parts of your pressure washer. Going
over the terminology below will make sure we’re on the same page.
2.1 COMPONENT IDENTIFICATION
BW3500 and BW3800
Nozzle Storage
Gas Cap
Fuel Tank
Oil Dipstick
Recoil Starter
Handle
Choke
Lever
Fuel
Valve
Trigger Safety
Spray Gun
Lance
Oil Drain Plug
Power Switch
Tires
High Pressure
Hose
Air Filter
Throttle
Lever
Nozzle
High Pressure
Hose Outlet
Water Supply
Inlet

6
TM
BW4400
Water Supply
Inlet
Nozzle Storage
Gas Cap
Fuel Tank
Oil Dipstick
Recoil Starter
Handle
Choke
Lever
Fuel
Valve
Trigger
Safety
Spray Gun
Lance
Power Switch
Tires
High Pressure
Hose
Air Filter
Throttle
Lever
Nozzle
High Pressure
Hose Outlet
Oil Drain Plug

7BW SERIES
3. GETTING STARTED
Setup of your pressure washer is designed to get you up and running as quickly as
possible. Cut the four corners of the carton from top to bottom instead of attempting
to lift it out of the box.
3.1 ASSEMBLING THE HANDLE
1. Slide the main handle onto the frame.
2. Pass the saddle bolts through the hole from the outside.
3. Tighten the knobs to secure it in place.
4. If equipped with an upper handle (BW4400 only), slide the upper handle
onto the main handle. Press in the spring pins until the upper handle slides
down all the way and snaps in place.
This part is
BW4400 Only

8
TM
3.2 PREPARE THE AIR FILTER
Prepare the air lter before your rst use. Check the maintenance schedule for a
complete cleaning guide.
1. Loosen top nut and remove the air lter cover. Remove the air lter
element.
2. Separate the foam pre-lter from the air lter element.
3. Inspect the paper lter inside the air lter element, shake lter or blow with
air to remove any dust and debris. Replace either lter if damaged.
4. Clean the foam pre-lter with soap and water or solvent and let dry
completely.
5. Wearing gloves, add new engine oil to the foam pre-lter. Work oil into foam
lter until saturated.
6. Squeeze and repeatedly use a towel to pat out excess oil. The result should
be a very lightly oiled pre-lter, if excess oil remains in the foam lter it can
seep through to the paper lter and damage it.
7. Add foam pre-lter back to air lter element and reinstall onto engine.
NOTE
Running the engine without the air lter will quickly degrade the engine
Always inspect air lter before using the pressure washer. Check and
clean the air lter according to the maintenance schedule.
Air Filter
Housing
Foam
Pre-Filter
Air filter element
with paper filter
Wing Nut

9BW SERIES
3.3 REPLACE THE TEMPORARY PUMP OIL DIPSTICK
BW3800 and BW4400 Only
Your pressure washer ships with a red non-vented oil ll plug. Before starting the
pump replace the red non-vented dipstick with the included vented oil ll plug.
Air Filter
Housing
Foam
Pre-Filter
Air filter element
with paper filter
Wing Nut

10
TM
3.4 ADD ENGINE OIL
1. Ensure the pressure washer is on a level surface.
2. Unscrew one of the two oil dipsticks and clean the dipstick.
3. Check the oil level by reinserting the oil dipstick without screwing it back in.
Remove the dipstick and examine the oil level. If the level is at or below
the minimum oil level marked on the dipstick, rell to the maximum oil level
mark.
4. Reinsert the dipstick and tighten securely.
NOTE
Oil max. capacity:
BW3500: 600 mL
BW3800: 700 mL
BW4400: 1.1 L
Do not tilt the pressure washer when adding engine oil. This could result
in overlling and damage to the engine.
Using non-detergent or 2-stroke oil could shorten the engine’s working life.
Use high quality engine oil with strong detergents.
Handle and store the engine oil with care, avoid getting dirt or dust into
the engine oil.
Do not mix different engine oils.
Before the engine oil falls below the safety margin, the low oil alert
system will automatically shut off the engine. The low oil light will turn on.
To avoid the inconvenience of unexpected engine shutoff, check the
engine oil level as often as possible.
Use 4-stroke engine oil, certied to meet or exceed API standard SG,
SF, SAE ratings
Maximum Oil Level
Minimum Oil Level
0°C 10 20 30 40 50-10-20-30
20 32°F 40 60 80 100 120
°C
°F0-20
15W-50
10W-30
Synthetic 5W-30
5W-30
Effective Viscosity Range of Engine Oils
8.6
8.6.2)Ta
aft
8.6.2)Take off the spark arrester
after the engine cool down.
8.6.2)Take off the spark arrester from the
after the engine cool down.
Maximum Oil Level
Minimum Oil Level
0°C 10 20 30 40 50-10-20-30
20 32°F 40 60 80 100 120
°C
°F0-20
15W-50
10W-30
Synthetic 5W-30
5W-30
Effective Viscosity Range of Engine Oils
8.6
8.6.2)Ta
aft
8.6.2)Take off the spark arrester
after the engine cool down.
8.6.2)Take off the spark arrester from the
after the engine cool down.
Maximum Oil Level
Minimum Oil Level
0°C 10 20 30 40 50-10-20-30
20 32°F 40 60 80 100 120
°C
°F0-20
15W-50
10W-30
Synthetic 5W-30
5W-30
Effective Viscosity Range of Engine Oils
8.6
8.6.2)Ta
aft
8.6.2)Take off the spark arrester
after the engine cool down.
8.6.2)Take off the spark arrester from the
after the engine cool down.

11 BW SERIES
3.4 ADD ENGINE OIL
1. Ensure the pressure washer is on a level surface.
2. Unscrew one of the two oil dipsticks and clean the dipstick.
3. Check the oil level by reinserting the oil dipstick without screwing it back in.
Remove the dipstick and examine the oil level. If the level is at or below
the minimum oil level marked on the dipstick, rell to the maximum oil level
mark.
4. Reinsert the dipstick and tighten securely.
NOTE
Oil max. capacity:
BW3500: 600 mL
BW3800: 700 mL
BW4400: 1.1 L
Do not tilt the pressure washer when adding engine oil. This could result
in overlling and damage to the engine.
Using non-detergent or 2-stroke oil could shorten the engine’s working life.
Use high quality engine oil with strong detergents.
Handle and store the engine oil with care, avoid getting dirt or dust into
the engine oil.
Do not mix different engine oils.
Before the engine oil falls below the safety margin, the low oil alert
system will automatically shut off the engine. The low oil light will turn on.
To avoid the inconvenience of unexpected engine shutoff, check the
engine oil level as often as possible.
Use 4-stroke engine oil, certied to meet or exceed API standard SG,
SF, SAE ratings
Maximum Oil Level
Minimum Oil Level
0°C 10 20 30 40 50-10-20-30
20 32°F 40 60 80 100 120
°C
°F0-20
15W-50
10W-30
Synthetic 5W-30
5W-30
Effective Viscosity Range of Engine Oils
8.6
8.6.2)Ta
aft
8.6.2)Take off the spark arrester
after the engine cool down.
8.6.2)Take off the spark arrester from the
after the engine cool down.
Maximum Oil Level
Minimum Oil Level
0°C 10 20 30 40 50-10-20-30
20 32°F 40 60 80 100 120
°C
°F0-20
15W-50
10W-30
Synthetic 5W-30
5W-30
Effective Viscosity Range of Engine Oils
8.6
8.6.2)Ta
aft
8.6.2)Take off the spark arrester
after the engine cool down.
8.6.2)Take off the spark arrester from the
after the engine cool down.
Maximum Oil Level
Minimum Oil Level
0°C 10 20 30 40 50-10-20-30
20 32°F 40 60 80 100 120
°C
°F0-20
15W-50
10W-30
Synthetic 5W-30
5W-30
Effective Viscosity Range of Engine Oils
8.6
8.6.2)Ta
aft
8.6.2)Take off the spark arrester
after the engine cool down.
8.6.2)Take off the spark arrester from the
after the engine cool down.

12
TM
4. PRE-OPERATION CHECK
These quick checks should be done each time the pressure washer is started to
ensure you get the most out of your pressure washer.
Set the pressure washer on a level surface and the power switch to OFF.
WARNING!
Exhaust gas contains poisonous carbon monoxide. Never run
the pressure washer in an enclosed area. Be sure to provide
adequate ventilation. Operate the pressure washer on a level
surface. If the pressure washer is tilted, fuel spillage may result.
Keep away from rotating parts while the pressure washer is
running. The pressure washer is air-cooled and may be damaged
if ventilation is inadequate.
4.1 CHECK PUMP OIL LEVEL
1. Ensure the pressure washer is on a level surface.
2. Unscrew one of the two oil dipsticks and clean the dipstick.
3. Check the oil level by reinserting the oil dipstick without screwing it back in.
Remove the dipstick and examine the oil level. If the level is at or below
the minimum oil level marked on the dipstick, rell to the maximum oil level
mark.
4. Reinsert the dipstick and tighten securely.

13 BW SERIES
4.2 CHECK THE FUEL LEVEL
WARNING!
Gasoline is highly flammable and explosive under certain
conditions. Refuel in a well-ventilated area with the engine
stopped. Do not smoke or allow open flames or sparks in the
area where the pressure washer is being refueled or where
gasoline is stored. Do not overfill the tank. Be careful not to spill
fuel when refueling. Wipe up any spilled gasoline and let the area
dry before starting the engine.
Gasoline substitutes such as gasohol are not recommended.
They may be harmful to the fuel system components.
1. Check the fuel level by removing the fuel tank cap to visually check the
level.
2. Add fuel until the level reaches 1.5" below the top of the neck. Tighten the
fuel cap securely after relling.
NOTE
Only use unleaded gasoline (Pump Octane 87 or higher).
Never use stale or contaminated gasoline, or an oil/gasoline mixture.
Avoid getting dirt or water into the fuel tank.
Do not use a mixture of gasoline containing methanol. This will cause
serious damage to the engine.
Use of gasoline with an ethanol content greater than 10% can damage
the engine and fuel system and will void the manufacturer’s warranty.

14
TM
4.3 CHECK THE COLD WATER SUPPLY
Check local regulations of your municipal water company to check if
a backow prevention device is required when hooking up to drinking
water. This ensures no feedback of chemicals will return to the water
supply. Use a water lter to avoid potential damage from dirt in the
water supply.
Garden hose must be at least 3/4" diameter.
Flow rate of water supply must not fall below 8.0GPM. You can ensure
this by making sure your garden hose can ll a 5 gallon pail in 38
seconds or less.
The water supply temperature must not exceed 40°C/104°F
Never use the pressure washer to draw in water contaminated with
solvents eg. paint thinners, gasoline, oil etc.
Always prevent debris from being drawn into the unit by using a clean
water source and additional water lter.
DO NOT operate pressure washer without the water turned on.
4.4 ASSEMBLE THE SPRAY GUN AND HOSES
DANGER!
NEVER direct the water flow at people. The high pressure jet can
be dangerous if misused and must not be directed at people,
animals, electrical devices or the unit itself. DO NOT TREAT
FLUID INJECTION AS A SIMPLE CUT! Seek medical help
immediately.
1. Rotate the coupler on the trigger handle assembly clockwise to tighten the
spray wand. Tighten by hand.

15 BW SERIES
2. Attach the spray gun to the high pressure hose by pulling back on the collar
of the female hose tting and inserting the male spray gun end into it. Tug
on the connection to ensure the connection is secured.
Install the Detergent Siphon Hose
BW3500
4.3 CHECK THE COLD WATER SUPPLY
Check local regulations of your municipal water company to check if
a backow prevention device is required when hooking up to drinking
water. This ensures no feedback of chemicals will return to the water
supply. Use a water lter to avoid potential damage from dirt in the
water supply.
Garden hose must be at least 3/4" diameter.
Flow rate of water supply must not fall below 8.0GPM. You can ensure
this by making sure your garden hose can ll a 5 gallon pail in 38
seconds or less.
The water supply temperature must not exceed 40°C/104°F
Never use the pressure washer to draw in water contaminated with
solvents eg. paint thinners, gasoline, oil etc.
Always prevent debris from being drawn into the unit by using a clean
water source and additional water lter.
DO NOT operate pressure washer without the water turned on.
4.4 ASSEMBLE THE SPRAY GUN AND HOSES
DANGER!
NEVER direct the water flow at people. The high pressure jet can
be dangerous if misused and must not be directed at people,
animals, electrical devices or the unit itself. DO NOT TREAT
FLUID INJECTION AS A SIMPLE CUT! Seek medical help
immediately.
1. Rotate the coupler on the trigger handle assembly clockwise to tighten the
spray wand. Tighten by hand.

16
TM
BW3800
BW4400
1. Attach one end of the detergent siphon hose to the barb tting near the
high pressure hose connection of the pump.
2. Place the other end of the siphon hose with lter into the built-in detergent
8.6
8.6
8.6.3)Us
sp
re
8.6.4)Re
8.6.3)Use abrush to remove carbo
spark arrester . If the spark a
replace it.
8.6.4)Reinstall the spark arrester a
8.6.3)Use abrush to remove carbon depos
spark arrester . If the spark arrester i
replace it.
8.6.4)Reinstall the spark arrester and muff