Waterax MARK-3 User manual

MARK-3®Watson Edition
Owner's Manual
Publication Date: 06/2023
Publication Number: 702135, Rev.1

06/2023 –Page 2 of 62
This document provides information proprietary to WATERAX Inc. and cannot be used
or disclosed without WATERAX’s written authorization.
WATERAX Inc. reserves the right to make changes without notice in its products or components as
research and development or marketing conditions warrant. Changes affecting the operation of any
component in this manual will be reflected in a subsequent revision. WATERAX Inc. assumes no
responsibility for any omissions or errors that may appear in this document or for any damages that may
result from the use of information contained herein.
The following are trademarks or brand names of WATERAX Inc.: WATERAX, ‘WE MOVE WATER’.
All other trademarks used in this manual are the exclusive property of their owner.
MARK-3®Watson Edition Owner's Manual
Publication No.: 702135, Rev. 1
Publication Date: 06/2023
First Edition: June 2023
Published by:
WATERAX Inc.
6635 Henri-Bourassa W.
Montreal, Quebec H4R 1E1
CANADA
© 2023 WATERAX Inc.
All rights reserved
Printed in Canada

WATERAX MARK-3 Watson Edition Owner's Manual
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Contents
Important Safety Instructions....................................................................................................................4
Personal Safety Advisory ..........................................................................................................................4
Warnings....................................................................................................................................................4
Preventing Damage to Equipment ............................................................................................................5
Introduction .................................................................................................................................................6
About this Manual......................................................................................................................................6
About the MARK-3 Watson Edition ...........................................................................................................6
Parts Identification.....................................................................................................................................7
Pump Operation ..........................................................................................................................................8
Pre-Operation Checklist ............................................................................................................................8
User Interface (UI).....................................................................................................................................8
Fuel Supply................................................................................................................................................9
Pump Connection and Priming................................................................................................................11
Engine Startup.........................................................................................................................................12
Discharge.................................................................................................................................................13
Shutdown.................................................................................................................................................13
Cold Weather Operation..........................................................................................................................13
Removing or Attaching the Pump End ....................................................................................................14
Basic Care and Storage ..........................................................................................................................14
Troubleshooting.......................................................................................................................................16
Maintenance ..............................................................................................................................................19
Service........................................................................................................................................................20
Recoil Starter...........................................................................................................................................20
Fan Cowl Assembly.................................................................................................................................24
Flywheel & Ignition ..................................................................................................................................25
Electronics...............................................................................................................................................28
Air Filter & Throttle...................................................................................................................................31
Carburetor................................................................................................................................................32
Fuel Connector & Purge Bulb..................................................................................................................35
Muffler Assembly.....................................................................................................................................36
Pump Hub................................................................................................................................................37
Pump Clamp............................................................................................................................................37
Frame Assembly......................................................................................................................................38
Decals......................................................................................................................................................38
Engine......................................................................................................................................................39
Pump End................................................................................................................................................47
Pump Test kit...........................................................................................................................................51
Fuel Line..................................................................................................................................................52
Fuel Tank.................................................................................................................................................52
Tools........................................................................................................................................................53
Technical Data...........................................................................................................................................55
Trademark..................................................................................................................................................58
Notes ..........................................................................................................................................................59
Warranty.....................................................................................................................................................61

WATERAX MARK-3 Watson Edition Owner's Manual
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IMPORTANT SAFETY INSTRUCTIONS
Personal Safety Advisory
READ THIS MANUAL BEFORE OPERATING YOUR PUMP!
The improper use of the WATERAX pump could result in
serious injuries as well as damage to the pump. This manual
contains very important safety information that MUST be read,
understood, and followed to safeguard you and your
equipment from harm, as well as specific information on the
proper use and care of your engine. Any operator should
familiarize himself with the apparatus and its capabilities before trying to operate the
equipment in an emergency situation. Please read this entire manual before using your
WATERAX pump and follow all Personal Safety Advisories. This pump must only be
operated by trained personnel.
Warnings
 Do not operate if mentally or physically fatigued.
 Always inspect hoses and piping to avoid burst injuries.
 No modification and/or alteration may be made to the pump. Any such modification not
only voids the pump warranty but can endanger pump operators.
 Do not operate the pump higher than the maximum rated pressure. Always run the unit at
the lowest pressure required for the application to enhance operator and equipment
safety.
 Use only pipe, hose, and fittings that are rated at or above the maximum pressure rating
of the pump, or according to what maximum pressure the system was designed for,
whichever is lower.
 Maximum Pressure Rating: 600 PSI (41 bar)
 Maximum Allowable Pump Intake Pressure: 200 PSI (13.8 bar)
 Slowly close valves and use slow close valves wherever possible to prevent danger to
other line operators and to prevent water hammer which could damage the pump and its
piping components.
 Always wear eye and ear protection when operating the pump unit.
 Ensure sufficient lighting (5 lx min.) during operation.
 Never run the engine in a closed or confined area. Exhaust gas contains carbon
monoxide which is poisonous. Avoid inhalation of exhaust gas.
 Refuel engine with care. Gasoline is extremely flammable, and gasoline vapor can
explode. Refuel in a well-ventilated area, with the engine stopped. Use only fuel and oil
type as recommended.
 Be alert and never touch any part of the engine exhaust system while the engine is
running. Always allow enough time, after stopping the unit, for proper cooling of these
parts and surrounding area. Wear protective gloves.
 Leaving the pump running with all the discharge valves closed is called deadheading the
pump (shut-off). The pump should not be left in this mode for more than a minute.
Leaving in this condition for any length of time will cause the pump to overheat and can
damage the pump. Additionally, the pump end and the water inside it can become
extremely hot and cause severe burns. Be careful when opening the discharge valve
and avoid touching the pump end. To avoid overheating the pump, a re-circulation line

WATERAX MARK-3 Watson Edition Owner's Manual
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(if provided) should be opened, or a discharge line left slightly open to allow fresh water
to continue to enter the pump.
 Be careful not to pinch your fingers. Do not place your fingers near the cooling fan and
engine output shaft when the engine is running. Never operate without the fan shield.
 Relieve all system pressure before doing any service work on the pump.
PREVENTING DAMAGE TO EQUIPMENT
The following recommendations will help avoid damage to your equipment:
 Always use the proper fuel mixture.
 Do not run the engine at full speed until thoroughly warmed up.
 Do not lift strainer out of the water while pump is operating.
 Do not run engine with pump disconnected.
 Do not run the pump when dry.
 Always draft water using a foot valve suction hose strainer.
 Position the foot valve to avoid drawing any type of sediments into the pump. Sand, silt,
and mud are abrasive: do not allow the foot valve strainer to rest on bottom of lake or
riverbed.
 Position the foot valve to avoid drawing air into the pump. Keep foot valve approximately
1 foot (30 cm) below the water surface. Securely attach in the presence of waves.
 Check strainer frequently to make sure that it is not clogged with moss, leaves, etc.
 Flush the pump with fresh water if the pump has been used to pump salty, brackish, high
mineral content water, water containing debris, or foam injected water. Check that debris
is cleared before using pump again.
 Drain pump after final use.
 During freezing weather, drain the pump and lines of all water. You can also pour some
plumbing antifreeze into the pump and circulate it through the pump and plumbing system.
 Pumps should not be operated without water for any extended period of time or without
discharging water. Operating the pump in such a manner can overheat the pump causing
damage to seals, or pump internals.
 It is recommended that all parts be replaced with genuine WATERAX parts.

WATERAX MARK-3 Watson Edition Owner's Manual
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INTRODUCTION
About this Manual
This manual contains important safety, operation, troubleshooting and servicing procedures
for the MARK-3®Watson Edition. The first part of the manual is dedicated to the operation of
the unit. The second part is dedicated to the maintenance and servicing of the unit.
It is recommended that all information provided in this manual be carefully read and
understood before performing any operation or maintenance to the pump.
The procedures listed in this manual are general operating and maintenance procedures.
They should be taken in addition to any procedures, policies and guidelines established by
the authority having jurisdiction or the apparatus manufacturer. Where conflicts arise, all
parties (authority having jurisdiction, the apparatus manufacturer, and WATERAX Inc.) will
need to be contacted to determine the best resolution. The solution will need to address the
safety of the operator along with the proper performance and life expectancy of the unit.
These instructions cover most wildland pump applications. If the application the pump is
being used for does not fall into these general guidelines, consult WATERAX for any
additional safeguards, operating, or maintenance considerations that may be required.
Please consult www.waterax.com for additional documentation related to this product such
as the WATERAX product guide, parts catalog, technical notes, news, and other updates
about WATERAX and its goods and services. Refer to “Tech-Notes” for the latest engineering
changes and recommendations, which have been introduced since the publication of this
manual.
About the MARK-3 Watson Edition
The MARK-3 Watson Edition provides unparalleled performance, reliability, and ease of
operation in a lightweight and compact design.
It couples a lightweight 4-stage high-pressure pump end with a purpose-built 140cc high-
performance two-stroke engine. It includes an intuitive user interface with advanced safety
and protection features. A built-in fuel priming system significantly improves startability.

WATERAX MARK-3 Watson Edition Owner's Manual
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Parts Identification
A. Engine
B. Pump Intake (suction)
C. Pump Discharge
D. Quick Release Pump Clamp
E. Fuel Connection
F. Engine Drain Plug (not shown)
G. Air Filter
H. Choke
I. Carburetor Purge Bulb
J. User Interface (UI)
K. Throttle
L. Rewind Starter
M. Manual Start Pulley (not shown)
N. Spark Plug
O. Muffler & Heat Shield
P. Carry Handle
Q. Backpack Frame
R. Foot Hold
A
D
B
C
E
G
I
J
K
.
O
P
R
H
N
Q
L

WATERAX MARK-3 Watson Edition Owner's Manual
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PUMP OPERATION
Pre-Operation Checklist
Before using your pump, follow this verification procedure:
1. Visually inspect product. When you first receive your pump, inspect the product and
check for any damage. Notify the supplier if any damage is found.
2. Check that all suction and discharge hoses are structurally sound and do not leak.
3. Inspect all safety features and verify that they are in good order before using the pump.
4. Each time you plan to use the pump, check for damage that may have occurred during
previous use. Notify your manager that the equipment requires repair. Remember that
damaged equipment can expose you to safety hazards.
User Interface (UI)
The User Interface Module (UIM) continuously monitors the
engine speed and operating temperature. In the event of an
overspeed condition (e.g., loss of prime), or overheat
condition, the UIM will automatically shut down the engine to
prevent the risk of damage.
The UI has an integrated multi-color LED to display operating
status and an OFF switch to manually shut down the engine.
When the engine is stopped, the UIM will store the last
operating status and display it when restarting. This is useful
in troubleshooting scenarios.
LED States
Green Flashing
 Engine in warm-up stage.
Green Solid
 Engine is warmed up.
 Can safely operate at wide open throttle.
Yellow Flashing
 Engine speed below 1,000 rpm (low speed condition): engine shut down.
 Engine likely ran out of fuel.
Yellow Solid
 Wiring issue.
 Engine temperature sensor disconnected.
 Engine temperature sensor shorted.
 Off button disconnected or loose contact.
 Such conditions will never shut down the engine.
Blue Flashing
 Engine speed above 9,000 rpm (overspeed): engine shut down.
 Loss of prime condition.
Red Flashing
 Engine temperature exceeds warning temperature threshold: warning.
 Engine temperature exceeds max. allowed temperature: engine shut down.
Red Solid
 Engine temperature gradient too high: engine shut down.
 Very lean adjustment.
 No oil in fuel.
OFF
button

WATERAX MARK-3 Watson Edition Owner's Manual
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Fuel Supply
Fuel mixture
The MARK-3 is powered by a 140cc two-cycle (two-stroke) engine.For lubrication, the engine
requires a premixed fuel mixture of gasoline and oil.
GASOLINE: Minimum 87 octane unleaded quality automotive
grade gasoline (maximum 10% ethanol)
OIL: High quality two-cycle mixing oil specifically
designed for use on air cooled engines with API-
TC, JASO-FD and ISO-L-EGD certification.
WATERAX recommends Amsoil Saber®
Professional Synthetic.
FUEL MIX RATIO: 50:1 (gas to oil)
Important: Not enough emphasis can be placed on the use of the correct gasoline and oil
mixture. Using less than the recommended portion of oil will cause overheating and possible
engine damage. Using more than the recommended proportion of oil will cause spark plug
fouling, erratic carburetion, excessive exhaust smoke and rapid carbon deposits.
Important: Do not use two-cycle mixing oil made for water cooled engines (TCW).
Gasoline, octane, and ethanol
WATERAX recommends using high quality automotive grade gasoline with a minimum
octane rating of 87 (AKI) and a maximum ethanol concentration of 10% in its fuel mix for the
MARK-3.
It is important to note that gasoline has a shelf life. Depending on storage conditions, gasoline
can go stale in a matter of weeks. Gasoline will deteriorate in three ways:
1. The more volatile components of the gasoline evaporate, leaving behind a heavier
gasoline which can lead to inferior engine performance and a more difficult engine to
start.
2. Certain hydrocarbons in the gas react with oxygen (oxidation) producing new and harmful
compounds. The stale gasoline will smell sour, its color will go dark, and gummy particles
can appear in the gas. This can lead to poor engine performance and reliability issues
with the carburetor.
3. Water contamination, which is normally caused by condensation, can be catastrophic to
the engine. Gasoline containing ethanol is more susceptible to that problem. Ethanol is
hydrophilic, which means that it tends to draw in moisture. If the water contamination is
severe enough, the ethanol will separate from the gasoline and drop to the bottom of the
fuel tank. Since water and oil do not mix well, this ethanol and water blend can cause
severe engine problems due to the lack of lubrication.
To prevent any damage to the engine, it is highly recommended to only use fresh gasoline.
Depending on storage conditions and ethanol content, gasoline typically has a shelf life of
three to six months. Gas stabilizers (e.g., STA-BIL®) can be used to increase the gasoline’s
shelf life; however, it will not restore back bad gasoline.
Winter vs. summer-grade gasoline
Winter-grade gasoline as a higher Reid Vapor Pressure (RVP), which is a measure of how
easily petroleum liquids evaporate. The RVP changes to accommodate seasonal

WATERAX MARK-3 Watson Edition Owner's Manual
06/2023 –Page 10 of 62
temperature variations that affect both the performance of gasoline in an internal combustion
engine and emissions. In the winter, higher RVP ensures that gasoline combusts quickly at
low ambient temperatures. In the spring and summer when ambient temperatures are warm,
a lower-RVP gasoline prevents vapor lock, when too much vapor may prevent an engine
from starting or running properly. Thus, WATERAX strongly recommends using summer-
grade gasoline with the MARK-3, especially when ambient temperatures are hot, to ensure
optimal startability, operation and performance.
Supply recommended fuel to engine
1. Carefully mix the fuel as recommended in the Fuel mixture
section. Mix well.
2. Connect fuel supply line to fuel tank.
3. Prime fuel supply line by recirculating excess fuel into tank to
eliminate air bubbles and avoid air locks.
4. Connect fuel supply line to engine fuel connection.
5. Prime carburetor by pressing purge bulb (I) successively until
fuel travels up the clear fuel line and appears in the purge bulb.
Important: The use of the purge bulb will not flood the engine. However, excessive use of the
purge bulb will cause excess fuel to drip down the air filter.
Important: When refueling the fuel tank, it is recommended to use a fine strainer to capture
particles and prevent damage and/or clogging of the carburetor.
Important: It is recommended to keep the fuel tank at the same level as the pump unit to help
prevent fuel cavitation. Ensure that the height between the bottom of the fuel tank and the
carburetor does not exceed 2 ft (0.6 m).
Important: It is recommended to keep the length of the fuel line to a maximum of 6 ft (1.8 m)
to help prevent fuel cavitation. The fuel line should be just long enough to allow to position the
fuel tank in a secure location, away from a heat source (i.e., muffler).
Warning: Ensure that the fuel tank is positioned away and at a safe distance from the muffler
to avoid any potential accident. Always refuel with care.
Flooded engine
Flooding an engine refers to an accumulation of excess fuel in the cylinder and crankcase
due to an excessive use of the choke. This condition makes the engine nearly impossible to
start without clearing the engine of the excess fuel.
Clearing a flooded engine
1. Disconnect the spark plug cable and remove the spark plug.
2. Re-connect the spark plug cable to the spark plug. Place the spark plug in contact with
the cylinder head to ground the spark plug.
Important: Failure to ground the spark plug can damage the ignition when cranking the
engine.
I

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3. With both choke and throttle in fully open position, pull starter rope several times until
excess fuel is exhausted.
4. Before reinstalling spark plug, clean and dry the electrode and insulator tip.
5. If engine is severely flooded, remove the engine drain plug and drain engine.
Pump Connection and Priming
1. Connect foot valve strainer to male end of suction hose, then fill suction hose with water.
Connect hose to the pump intake (B). Tighten coupling firmly with coupling wrench.
Manual Priming:
a) Loosen pump clamp and rotate pump so the
discharge is pointing upwards.
b) Prime by pouring water into the discharge until full.
c) Pump can also be primed by “jerking” the suction
hose until water flows from pump’s discharge port.
WATERAX Hand Primer: Connect hand primer to
discharge port and pump until water is drawn into pump.
2. Connect discharge hose, nozzles, etc. to pump
discharge (C); tighten coupling firmly with wrench.
Important: To provide proper operation of the pump, the suction hose/strainer should be
submerged a minimum of 4 to 6 times the hose diameter into the water source.
DO NOT run pump dry.
DO NOT allow foot valve strainer to rest on bottom of lake or riverbed. Check strainer frequently
to make sure that it is not clogged with moss, leaves, etc.
DO NOT lift strainer from water while the pump is operating. Use a rope or other means to keep
strainer at proper height, approximately 1 foot (30 cm) below water surface. If strainer is too
close to the water surface, it will draw air and pump may lose prime.
To maintain optimum performance from your pump, follow these recommendations for
selecting and installing your suction hose:
▪ Use the shortest length possible; place the pump as close to the water as possible.
▪ Select reinforced crush resistant (non-collapsible) hose.
▪ To avoid air locks, flexible hose should rise gently from the water source to the
suction/inlet port without excessive dips, bumps, sharp angles or rise in its lay.
▪ Fit a foot valve suction strainer to prevent foreign matter from entering the pump.
▪ The installation and use of a suction float will aid in the performance of your pump, by
keeping suction away from the debris on the bottom of the dam or river.
▪ Ensure that the suction hose is completely submersed.
Limitations
Several factors can affect the pump’s ability to efficiently draft water. The following limitations
should be considered:
▪ Water temperatures above 95 °F (35 °C) can cause noticeable loss in performance.
▪ Barometric pressures below 29 in Hg (98 kPa) can also cause noticeable loss in pump
performance (specifically elevations > 2000 feet (610 m) above sea level).
▪ Restrictive hose and strainers can significantly decrease pump performance.
▪ Intake hose runs in excess of 10 feet (3 m) can reduce pump performance.
▪ Minimize the suction lift to prevent cavitation and minimize performance degradation.
In high suction lift setup, reduce the throttle to prevent tripping the overspeed cut-off.
C
B

WATERAX MARK-3 Watson Edition Owner's Manual
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Engine Startup
1. Close/engage choke (H), if engine is cold.
2. Move throttle lever to “START/WARM UP” (3
increments from “IDLE”).
3. Slowly crank engine until resistance (past
compression).
4. Pull the rope until recoil pawl engages the pulley,
then give starter cord a quick and steady pull.
5. Once engine fires, disengage choke and pull start
again if necessary.
6. Allow engine to warm up while UI LED blinks
green (approx. 2 min.).
7. Once UI LED becomes solid green, the unit can
be throttled up.
Important: The MARK-3 engine is broken-in at the factory. Full throttle operation can be used
provided the engine is given a thorough warm-up period beforehand.
Failure to allow engine to warm up may lead to piston scoring and possibly more serious
engine damage.
Recoil Starter Failure
If the recoil starter should break while the unit is on the fire line, the recoil starter can be
removed, thereby gaining access to a manual starter pulley which is part of the flywheel.
1. Remove the recoil starter.
a. Remove three 4 mm bolts holding on recoil starter. Keep bolts in a safe place.
b. Remove recoil starter.
c. Keep fan shield in place and rotate so that three holes are in line with mounting
points for recoil starter. (See images below)
d. Replace the three bolts to hold fan shield and fan cowl in place during operation.
2. Rotate piston to top dead center by hand.
3. Wrap a starter rope clockwise (from starter view) around the manual start pulley and pull.
Repeat until engine starts.
Warning: Never operate the pump without fan shield in place to avoid injury or damage to the
unit.
(CLOSED/
ENGAGED
POSITION)
H
START/WARM
UP POSITION

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Discharge Once the pump is primed, and with the engine running, you can begin to discharge water.
a) If pressure does not build in the discharge hose, the pump is not fully primed. Verify that
there is no leak between the suction hose and the pump end. Prime the pump again.
b) The engine works best at wide open throttle. Vary the discharge nozzle opening to adjust
the pump performance.
Warning: Leaving the pump running with all the discharge valves closed is called deadheading
the pump (shut-off). The pump should not be left in this mode for more than a minute. Leaving
in this condition for any length of time will cause the pump to overheat and can damage the
pump. Additionally, the pump end and the water inside it can become extremely hot and cause
severe burns. Be careful when opening the discharge valve and avoid touching the pump
end. To avoid overheating the pump, a re-circulation line (if provided) should be opened, or a
discharge line left slightly open to allow fresh water to continue to enter the pump.
Important: If the engine throttle is increased and the engine RPM increases without an
increase in pump pressure, the pump may be cavitating. Refer to the limitations listed at the
beginning of this section and see the troubleshooting section for a verification checklist and
possible solutions. Avoid running at WOT above a 12.7 mm (1/2") nozzle size. If running a
larger nozzle, reduce the throttle to avoid cavitation and tripping the overspeed protection.
Warning: Avoid running out of fuel when the engine is running at wide open throttle to avoid
lean conditions and potential engine premature wear.
Shutdown
Shut down the pump
1. After completing the pump operation, gradually reduce the engine speed and move
throttle to “IDLE” position.
2. Allow unit to run for approximately 2 minutes with throttle in this position for proper cool
down.
3. Press and hold the “OFF” button on the UI until engine shuts down.
After final use
4. Drain the carburetor. Run at idle with the fuel line disconnected until the engine stops to
drain the fuel system.
5. Drain the pump end. If the pump was last run with foam or water that is salty, brackish,
or high in mineral content, flush the pump with fresh water for a minimum of 2 minutes
or until the water is clear, and drain the pump end.
Cold Weather Operation
The pump can be run in below freezing temperatures if certain precautions are taken to avoid
the formation of ice in the pump.
1. After priming the pump, the unit should be run at low speed for a short period of time to
allow all components to warm up before continuing with the remaining operating
procedures.
2. Unless wrapped in a heater, drain the pump of all water if it is stopped for any length of
time. The engine/drive unit should be turned over a few revolutions to make sure all water
has been removed from the pump.
3. After use, drain the pump, manifolds, and lines of all water. You can also pour plumbing
antifreeze into the pump and circulate it through the pump and plumbing system.

WATERAX MARK-3 Watson Edition Owner's Manual
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Removing or Attaching the Pump End
The MARK-3 Watson Edition pump has a quick release pump clamp and detachable pump
end which facilitates the servicing of pump units and minimizes down-time in the field by
allowing the quick replacement of pump ends.
To remove pump from engine:
1. Lift pump clamp lever.
2. Release tension-adjusting knob.
3. Remove clamp.
4. Remove pump from engine.
To attach the pump end to the engine:
1. Install the coupling belt on the engine or
pump end coupling drive.
2. Align the teeth of the pump end coupling
drive with the coupling belt and install.
3. Install pump clamp with the lever on the top
side, with the tension knob orientated
towards the muffler.
4. Finger tighten tension knob to obtain a light
pressure on clamp link and close lever.
Important: Apply FINGER PRESSURE ONLY to close pump clamp lever. Excessive pressure
will damage or break the clamp link.
Basic Care and Storage
The basic care described in this section does not require any disassembly of the pump. For
any servicing procedures that require removing any part of the pump to access a component,
please see the Service section.
After each use:
1. Visually inspect the pump unit.
2. Make sure the mechanical rotary seal is not leaking.
3. Check the pump for external leaks.
4. Check the condition of the coupling belt. Replace if worn.
5. Check the engine for leaks.
6. Clean any dirt or debris from the pump unit. Use a mild soap and water solution.
7. Clean air filter.
8. Make sure cooling passages and cylinder fins are clean.
9. Make sure that spark plug is cleaned and has proper gap setting. If the spark plug gap
exceeds the recommended value of .020”-.024” (0.5-0.6 mm), replace.
10. Check throttle and choke control for proper operation.
11. Check the muffler for excessive carbon build-up. Clean if necessary.
12. Check the spark arrestor for excessive carbon build-up. Clean or replace if necessary.
13. Check fuel line and fittings for signs of wear, etc.
14. Check starter rope and mechanisms and replace if there are signs of wear.
Tension
knob
Lever
Coupling
belt

WATERAX MARK-3 Watson Edition Owner's Manual
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15. Make sure UIM is free of dirt and debris. Verify condition of wiring and connectors.
16. Note and report any performance irregularities or any abnormal mechanical sounds.
17. Make sure all necessary tools, spares, and accessories are with the pump.
Long-term storage
1. Completely drain the pump of all water.
2. Drain the carburetor. The engine can be run at idle with the fuel line disconnected until
the engine stops to drain the system.
3. Pour 0.17 oz. (5 mL) of 4-cycle engine oil (any viscosity will do) through the spark plug
hole in the cylinder head. Slowly crank the engine to cover the piston rings, cylinder, and
crankshaft with oil to protect the components from corrosion. Storage seal fogging oil can
also be used.
Important: 2-cycle mixing oil is not recommended as preservation oil; it tends to attract
moisture.
4. Follow any other products, components, apparatus, and departmental procedures and/or
guidelines before placing the unit in storage.

WATERAX MARK-3 Watson Edition Owner's Manual
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Troubleshooting
This section provides brief troubleshooting instructions for verifying the set-up and operation
of the pump. Each section describes a condition and lists possible causes along with a list of
items to check to identify the source of the problem and resolve it.
Pump Loses Prime or Will Not Prime
Air Leaks
 Verify that suction hose coupling is securely tightened.
 Check suction hose gasket.
 Check sealing face on pump end suction cover.
Air Trapped in
Suction Line
 Check that no part of the suction hose is higher than the pump intake. Pump
suction hose must be laid out with a continuous decline to the water source from
the pump intake.
Blocked or
Restricted
Intake Hose or
Strainer
 Remove blockage from the intake hose or strainer.
 Strainer should not be sitting at the bottom of the water source where debris can
be picked up. Clean off the strainer and raise to a position that is off the bottom
of the water source (floating strainers are available).
Pump Suction
Lift
Requirements
are Too High
 DO NOT attempt pump lifts exceeding 22 feet (6.7 meters) except at elevations
lower than 2000 feet (610 meters) above sea level.
 As elevation increases above 2000 ft (610 meters) above sea level, maximum
lift heightswill diminish. Check that the lift for the elevation the pump is being
required tooperate at is achievable.
Air Lock in the
Discharge
 Open the discharge valve to allow for the air to evacuate during the priming
operation.
Pump Does Not Meet Performance
Incompatible
Suction Hose
 Verifysuction hose diameter is at a minimum of 2” (51 mm). Any smaller diameter
hose will negatively impact the pump performance and suction lift.
Pump End Low
Performance
 Pump end impellers and diffusers are worn off and require replacement.
 Debris in the pump end. Clean.
Insufficient
Engine Power
 See Section “Engine Does Not Develop Normal Power And/Or Overheats”
 Check engine compression and complete engine repairs if required.
 An engine tune up may be needed to bring engine back to peak performance.
Gauge or
Instrument
Failure
 Check that all gauges are calibrated, and that all equipment is in proper
condition. Nozzles with dented edges and bent or damaged pitot tubes will
produce faulty readings.
Blockage
 Check hoses and suction strainer; remove any obstructions found.
 Check for debris wedged or caught in the impeller, diffuser, and suction cover.
Remove any obstruction found.
Ambient
Conditions
 An engine will lose approximately 3.5% of its power per every 1000 feet (305
meters) above sea level (lower air density). Adjust carburetor accordingly.
 High ambient temperatures, low barometric pressure, and high humidity will
negatively affect pump performance (lower air density). Adjust carburetor
accordingly.

WATERAX MARK-3 Watson Edition Owner's Manual
06/2023 –Page 17 of 62
Pump Cavitating
Lift Too High
 Restrictive or malfunctioning foot valve. Replace.
 Clogged strainer. Clean.
 Move pump closer to water source.
 Decrease pump’s intake hose length.
 Increase pump’s intake hose size.
Restrictions
 Check that the bottom of the suction hose at a minimum of 2 feet (0.6 meters)
from the bottom of the water source and correct if necessary.
 Check that the bottom of the suction hose/strainer is 4 to 6 times the hose
diameter below the water supply surface level and correct if necessary.
Engine Does Not Start, Runs Irregularly or Misses
Fuel Supply Tank
Empty
Refill fuel tank.
Carburetor Loose
Tighten nuts and/or
studs.
Fuel Supply Valve
Closed
Open supply valve.
Defective Carburetor
Repair or replace.
Air Vent on Fuel Tank
Closed
Open air vent or
unscrew cap.
Low Speed Mixture Jet
Misadjusted
See “Carburetor.”
Defective Fuel Supply
Hose
Replace.
High Speed Mixture
Jet Misadjusted
See “Carburetor.”
Dirty Fuel Strainer
Screen
Clean or replace.
Air Filter Dirty
Clean or replace.
Leak in Fuel Supply
System
Tighten or replace
fittings.
Spark Plug Fouled or
Defective
Clean or replace.
Fuel Mixture Too Rich
See “Fuel Supply.”
No Spark
See “Ignition System.”
Wrong Gasoline in
Fuel Mixture
See “Fuel Supply.”
Wrong Type of Spark
Plug
Use recommended
spark plug.
Water or Dirt in Fuel
System
Drain; flush thoroughly.
Improper Timing
See “Flywheel &
Ignition.”
Engine Backfires
Spark Plug Fouled or
Defective
Clean or replace.
Defective Carburetor
Repair or replace.
Improper Timing
See “Flywheel &
Ignition.”
Engine Sounds Like a Four-Stroke
Engine Not Warmed
Up Properly
Allow longer warm-up
period.
High Speed Mixture
Jet Misadjusted
See “Carburetor”
Too Much Oil in Fuel
Mixture
See “Fuel Supply.”
Air Filter Dirty
Clean or replace.
Improper Timing
See “Flywheel &
Ignition.”

WATERAX MARK-3 Watson Edition Owner's Manual
06/2023 –Page 18 of 62
Engine Does Not Develop Normal Power And/Or Overheats
Wrong Oil
See “Fuel Supply.”
Air Filter Dirty
Clean or replace.
Wrong Gasoline
See “Fuel Supply.”
Muffler Blocked
Replace muffler and/or
spark arrestor.
Fuel Mixture Too Lean
See “Fuel Supply.”
Low Speed Mixture Jet
Misadjusted
See “Carburetor.”
Fuel Mixture Too Rich
See “Fuel Supply.”
High Speed Mixture
Jet Misadjusted
See “Carburetor.”
Cooling System Dirty
Clean cooling system.
Improper Timing
See “Flywheel &
Ignition.”
Cooling System
Blocked
Remove any debris
blocking the cooling fan.
“Winter-Grade”
Gasoline: Vapor Lock
See “Fuel Supply.”
Carburetor Flooding or Runs Rich With High Speed (Main) Adjustment Shut Off
Dirt or Foreign
Particles Preventing
Inlet Needle From
Seating
Remove, clean and/or
replace. Press purge
bulb and marine bulb to
clear out the particles.
Diaphragm Lever
Spring Not Seated on
Lever Dimple
Remove lever and
reinstall.
Diaphragm Improperly
Installed in Carburetor
Replace diaphragm or
correct installation.
Improper Use of Choke
Disengage/Open choke.
Engine Will Not Accelerate
Low Speed Mixture Set
Too Lean
Enrich low speed
adjustment.
Diaphragm Gasket
Leaking
Replace.
Incorrect Setting On
Diaphragm Lever
Reset.
Main Fuel Orifice
Plugged
Remove diaphragm
cover, diaphragm,
diaphragm lever and
high-speed adjusting
screw. Clean out.
Diaphragm Cover
Plate Loose
Tighten.
Pulse Hole Partially
Blocked
Inspect intake side and
resolve cause of
blockage.
Engine Will Not Idle
Incorrect Idle Speed
Adjustment
Adjust idle speed.
Welch Plug Covering
Idle Discharge Ports
Not Sealing
Replace welch plug.
Engine Runs Out Lean
Fuel Tank Vent Not
Working Properly
Clean or replace.
Ruptured Fuel Pump
Diaphragm
Replace.
Leak in Fuel System
from Tank to Pump
Tighten or replace
fittings and lines.
Main Fuel Orifice
Plugged
Clean.
“Winter-Grade”
Gasoline: Vapor Lock
See “Fuel Supply”.

WATERAX MARK-3 Watson Edition Owner's Manual
06/2023 –Page 19 of 62
MAINTENANCE
Regular maintenance
Regular maintenance is a schedule of continuous systematic maintenance, designed to
prevent frequent or major breakdowns before they occur.
Warning: Before doing any maintenance to the pump, always ensure that the equipment
cannot be accidentally started. Follow any apparatus and/or departmental procedures or
guidelines regarding locking out the equipment.
Important: Maintenance on a fire pump should not be done on the fire line. Always check your
pump unit immediately after use.
Maintenance chart
The following maintenance intervals apply for normal
operating conditions only. If the unit is operated in harsh
conditions (very dusty environment, extreme temperatures,
abrasive water), shorten the intervals accordingly.
Servicing should be completed by a trained mechanic from
an authorized Service Center.
Only use WATERAX Genuine spare parts.
Before daily operation
After deployment
After fire season
125 hours
If problem
If damaged
Air filter
Clean
X
X
X
Replace
X
Ember separator
Clean
X
X
Replace
X
Fuel block / fuel adaptor
Inspect
X
X
X
Replace
X
X
External fuel tank
Clean
X
Spark plug
Replace
X
X
Spark arrestor
Clean
X
Replace
X
Recoil starter
Clean
X
X
Service
X
Cylinder cooling fins
Clean
X
X
Piston kit
Replace
X
Pump end
Inspect
X
X
X
Service
X
X
Frame
Inspect
X
X
Service
X
X
Vibration dampeners
Inspect
X
X
Service
X
X

WATERAX MARK-3 Watson Edition Owner's Manual
06/2023 –Page 20 of 62
SERVICE
This section includes instructions for the complete overhaul of the unit. Servicing should be
completed by a trained and experienced mechanic/technician. For any question regarding
servicing, contact WATERAX technical support.
Warning: It is important to respect the specified torque and application of Loctite®where
specified. Refer to the torque table at the end of the manual for torque values and Loctite
requirements.
Recoil Starter
The recoil starter assembly requires regular maintenance for optimal operation. Regular cleaning is
recommended, especially when the pump is operated in dusty conditions.
Parts Breakdown
ID
ITEM NO
DESCRIPTION
QTY
--
600632
RECOIL STARTER ASSEMBLY WATSON
--
1
701744
SCREW M5X0.8X14 HEX SOCKET CAP SS
DIN912
3
2
701927
WASHER M5 FLAT 5.3MM X 10MM SS DIN125
3
3
701778
HOUSING RECOIL STARTER WATSON
1
4
701885
SCREW M3X0.5X6 BUTTON HEAD TORX SS
4
5
701780
DISK LOW FRICTION RECOIL STARTER
WATSON
1
6
701781
SPRING WITH CASING RECOIL STARTER
WATSON
1
7
701783
PULLEY RECOIL STARTER WATSON
1
8
701787
PAWL RECOIL STARTER WATSON
1
9
701884
WASHER FRICTION RECOIL STARTER
WATSON
1
10
702003
COTTER PIN HAIRPIN RECOIL STARTER
WATSON
1
11
701978
HANDLE RECOIL STARTER WATSON
1
12
800128
R-544 BUFFER - RUBBER
1
13
800127
R-533 GUIDE FOR STARTER ROPE
1
14
701974
ROPE BLACK/RED 1500MM LG RECOIL
STARTER WATSON
1
Troubleshooting
Pawl slips on flywheel
 Pawl is worn out. Replace.
Pawl doesn’t open
when cranking
 Excessive friction between pawl and pulley. Clean or replace.
 Lack of friction between hairpin and shaft. Clean the shaft. Replace the
cotter hairpin.
Rope doesn’t rewind
back
 Lack of tension on the spring. Ensure three turns of tension on the spring.
 Interference between rope and housing: rope is too long, too large, or not
wound properly in the pulley. Re-assemble. Use approved rope size of
11/64” (4.4 mm) and length of 59” (1500 mm).
 Excessive friction between pulley and shaft. Clean and lubricate with
MOLYKOTE®1122 grease. Replace pulley if necessary.
 Rewind spring is jammed. Lubricate with light machine oil or silicon-based
lubricant. Replace if necessary.
 Rewind spring interferes with the housing. Ensure low friction disk is
installed. Replace if worn.