Shown,
XMV 3400 rpm D version - 1" with Gas Engine Flange (F24)

If your pump looks similar in design to the pump shown above,
then it is probably an AR pump.

AR is an abbreviation for Annovi Reverberi.
The AR pump is an Italian made pump marketed here in the USA.
We consider the AR pump an excellent pump for your dollar value.
If taken care of this pump will last you through many
years of good service.

Many Hot and Cold water pressure washer manufacturers
here in the USA use the AR brand pump when building their washers.

To help you troubleshoot an AR Pump we have provided some topics
below to consider. We also provide a table to choose
repair kits by part number for your AR pump.

Over time your pressure washer has lost pressure.


Several things can cause a loss of pressure.

Non Pump related problems causing pressure loss.

Check the condition of your spray nozzle tips. The hole in the tip is a precision sized hole and it is this hole in the spray tip that creates a back pressure on the pump and unloader. If this hole becomes worn over time from water errosion, then it will be larger in size than its original specification. A larger hole will cause less back pressure and your total cleaning power has been reduced.

Next, consider thie idea that someone may have lost the spray tip and replaced it with one from another source, not considering the proper application and hole size.

Next, consider your type of spray nozzle. Some manufacturers use an insert type of spray nozzle. The "hole or orifice" is drilled through an inserted "set screw" type of component that is threaded into the inside of the spray nozzle. This type of design is on the "push and pull" and "twist to adjust" type of variable spray nozzle ends. These variable type of spray nozzles are known to lose the insert and you will then lose your pressure because you now have a larger hole from where the nozzle insert is missing.

A variable nozzle stuck in the "low pressure" positon is pretty obvious also.

Pump related pressure loss.


A pump without a water inlet screen or filter is a pump about to fail!

Sand is in just about all non filtered water and all it takes is just a little bit of sand or trash to cause a pump to lose pressure.

The sand or trash can lodge in the check valves of the pump.
The check valves are what "traps" the pressurized water under pressure. There are in all triplex pumps (pumps with 3 plungers) 6 check valve retainer assemblies. The retainers are what holds the check valve, spring, and seat in proper position as an assembly.
If a piece of sand or trash comes to rest in between the valve and seat, then it will hold the valve open so pressurized water can then leak back to the non pressure side of the check valve.

Check valves can become worn. If the valve or the seat has a worn place on the surface or is "tilted" out of proper position, both components will contribute to a loss of pressure.

The check valves are located under the 6 plugs that are on the head of the pump. You can remove the brass plug from each valve position and remove the check valve. Be careful not to damage the valve retainer assembly when removing the assembly. We use a small screw driver to "tilt" the retainer from its seated position and then a "hook" type tool to pull the assembly from its place.

Once you have the valve assembly removed, and with everything still assembled, look for the sand or trash in between the valve and seat. Look for valves not seating properly, they will sometimes be tilted or not sitting straight. With a small screw driver, or similar tool, push the valve open and look for wear evidence. Wear is sometimes hard to detect by the untrained eye, but it shows itself in the form of metal surface differences. A worn spot on a valve or seat will be the spot that looks different than all the remaining and similar surrounding surface. Once a valve starts to wear, it normally will continue to wear in the same place. The wear comes from water erosion and dirt and trash in the water. If you find one valve that is stuck open or worn, you will probably find more. In any case for any reason, replace all 6 valve assemblies.

Broken plungers can also contribute or cause a loss of pressure. The plungers are in a set of 3 on a "triplex" pump. The plungers push water from one side of the check valve to the other side. This plunger action under high rpm creates the pressure. If a plunger is broken it can not move the water. You will in theory realize a one third reduction in water pressure for each plunger that is broken. A cracked plunger is about to break, so if you find one that is cracked, replace it. Do not continue to use it because if it breaks while in use, it can cause further damage to your pump.

An improperly set unloader or stuck in bypass can cause low pressure or no pressure.

The unloader is the flow component that "unloads" the pump when a no pressure demand is on the pump. When you pull the trigger on your spray gun, you are putting a demand on the pump for pressure. The unloader shifts into a pressure mode and sends pressurized water to the hose and out through the gun and nozzle. When you release the trigger gun, shutting off water flow, the unloader senses the increased back pressure and shifts to "unload" the pump from creating pressure. It is this position that is called the "bypass" position and if your unloader is stuck in the bypass position, it will continuously send water back to the inlet side of the pump and will not shift to a pressure mode. Need a new Pump?


Need a replacement Unloader?

No pressure, your nuloader may be stuck in "bypass".
Installing an AR unloader is a simple task.
We not only build pressure washers, but
will help you "Re Pump" yours.

For the kits below each kit comes with enough parts for a complete repair.

Check valves come with 6 valve assemblies

Water and Oil Seal Kits
come with enough to do all three pistons.
Piston kits come with 3 pistons.

SITE MAP CONTACT US Parts Counter AR PUMPS
AR PARTS PRICING AR Pumps PRICING AR ACCESSORIES PRICING AR UNLOADERS
Briggs & Stratton Engines Honda Engines Tecumseh Engines
AR Pumps
By Model Number


This web site has been made available to you for the enhancement of the services we provide to our customers. We've provided a number of resources here to help you resolve Generator and Pressure Washer problems, find parts you need, and suggest improvements to our service.



Copyright 2014
AAAA Generator and Pressure Washer, Inc.
DBA:ARKANSAS OPE
All rights reserved.
Last modified: december 8, 2014

All products mentioned are registered trademarks or trademarks of their respective companies.