# craftsman powerwasher 580.752000



## 2men&atrailer (Mar 22, 2011)

i have this washer and the b&s motor runs good

the problem is that i have very little water pressure 

i have part of the pump off and i see the 3 pistons but really don't understand what i am looking at and how to determine what is wrong

i can make pics if needed 

thanks for all the help

i love this place :wave:


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## paulr44 (Oct 14, 2008)

http://www.arnorthamerica.com/troubleshooting.html
http://www.the-power-washer-advisor.com/how-pressure-washers-work.html

A pressure washer is basically simple.
Water doesn't compress, so the pistons push it out the hose, the pressure being generated from the speed of the engine and the sizes of everything from the piston to the gun, or wand tip (orifice).
Commonly, there are three areas I find to be the most troublesome.
1. Clogged / restricted wand tip or even behind it in the nozzle head.
2. Stuck or resticted unloader valve, which in essence controls the outlet pressure. I've seen pieces of o-rings jammed in the body side holes, and unloaders just plain old stuck, many times.
3. Check valves. These are simple poppet valves that let water flow in one direction. There are two valves for each piston chamber. One to let water in, the other out. They can become damaged from heat, or the valve plate can become dislodged and allow reverse flow.
There are other reasons, but usually you'll find physical damage, such as cracked pistons, cracked pump head, or water in the pump oil.
BE SURE to check the inlet screen where you screw the garden hose in...I do see that clogged up but kind of rare.
Paul


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## usmcgrunt (Sep 16, 2007)

Thank you very much Paul,great info and links to save for future reference!


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## 2men&atrailer (Mar 22, 2011)

i think the first thing to do by the reading that i have found 

i think it could be that unloaded valve because it just doesn't build pressure

i can take the spray nozzle off and use just the hose and you can see a little build in pressure but i can stop it with very little effort


but the pump doesn't get hot or make any sounds like broken parts are in there

please tell me what you think

thanks for the help

i love this place :wave:


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## usmcgrunt (Sep 16, 2007)

If you can post a picture of the pump or let us know the make of the pump,it could help in diagnosing your problem.You have to use a nozzle on the gun to test for pressure.Any nozzle except the black one,which is used for applying soap at LOW pressure,will work.As paul said,you could have a dirty OR bad unloader on the pump.If the unit was stored in freezing weather with water in the pump,you will probably need a new pump.Hope this helps.


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## paulr44 (Oct 14, 2008)

usmcgrunt said:


> If you can post a picture of the pump or let us know the make of the pump,it could help in diagnosing your problem.*You have to use a nozzle on the gun to test for pressure*.Any nozzle except the black one,which is used for applying soap at LOW pressure,will work.As paul said,you could have a dirty OR bad unloader on the pump.If the unit was stored in freezing weather with water in the pump,you will probably need a new pump.Hope this helps.


Like the Gyrene said.

Without the orifice, or gun tip on, there is pressure, just no velocity. How much pressure can't be determined without a gauge. Since your're comfortable taking it apart, inspect the unloader valve. You'll have to release all of the spring tension to check it for binding. TAKE A PICTURE or count the exposed threads BEFORE taking it apart, and put it back EXACTLY the way it was. ELSE, you could end up overpressurizing the system, and could damage something else, OR, it could work fine but make less pressure than it's rated for. The amount of spring tension is what controls the unloader function, thus the water pressure.


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## 2men&atrailer (Mar 22, 2011)

ok i will post pics of what i have and what it looks like

thanks for the help

i love this place :wave:


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## 2men&atrailer (Mar 22, 2011)

*pics*

pics that yo asked for 

if these pics are not of the right stuff please tell me so i may take new ones that will help me

i love this place :wave:


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## paulr44 (Oct 14, 2008)

When you squeeze the trigger on a pressure washer, the water flow is returned to the hose and gun. When you release the trigger, the unloader valve re-seats. If it's sticky, stuck, jammed up with foreign matter it can reduce or eliminate the high pressure the system is designed to produce.

MOST of the time, as I've said, I look at the unloader as the first suspect.

My basic SOP.
Check engine and pump oils.
Hook up the unit to water to test-run it.
Purge air by holding the trigger down for awhile.
Run the unit.
OBSERVE the unloader valve operation when going squeezing the trigger, releasing it and repeating.

This simple test gives you an idea of the unit's condition. If the unloader doesn't move, and the gun tip and water inlet screen are clear, then you either have an stuck unloader or bad poppet valve in MOST cases.

The center "stud" of the unloader should move up when the trigger is squeezed, and down when released. The jam nuts on to of the spring are to lock the setting in place, or limit the knob movement. That's why I advised you take a picture or count the exposed threads. Many OEMs put a knob on the unloader to allow a limited change in pressure. Going beyond that limit can damage the pump by overloading it.

The bottom line is, that if the pistons and poppet valves are okay by physical inspection, and the gun tip, trigger assy. (have seen rust in the trigger assy resticting water flow) and water inlet screen are clear, then the unloader is not funtioning correctly in the majority of cases.

*NOTE* ANY RESTRICTION downstream from the unloader can and will have a negative effect on proper operation. That's why you have to ensure the hose, wand, trigger assy, lance, extensions, gun tips (orifices) are clear.

The type of unit you're working on is basically made to be a disposable unit. You can buy a whole new setup, engine and all like that, for about $270 to $300 at a box store. You may find a pump assy. for $125 to $200 online, but you'd still have an old, possibly rusty gun, and perhaps a tired engine.

FOR STORAGE, to prevent rust, hard water deposits, and freezing, I suggest:
http://www.pwmall.com/p-139800-ar64511-16-oz-bottle-ar-pump-saver-anti-freeze-solution.aspx


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## 2men&atrailer (Mar 22, 2011)

as far as i can tell that peace that you have circled their hasn't moved sence i got this unit

i think it is supose to move in inside the pump but i realy don't know

thisis not about money to me it is just an exersize in learning the way that these pumps work

then after that hopefuly i will have a presurewasher


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## keb (May 26, 2010)

You have a pump made by Faip.If you remove the pump from the engine you can check the engine shaft size.If it is 7/8" then you can replace it with an AR pump model SJW.Only cost about $99.00 on the internet.All of these vert.shaft pumps are rated for only about 200/300hrs.


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## paulr44 (Oct 14, 2008)

keb said:


> You have a pump made by Faip.If you remove the pump from the engine you can check the engine shaft size.If it is 7/8" then you can replace it with an AR pump model SJW.Only cost about $99.00 on the internet.All of these vert.shaft pumps are rated for only about 200/300hrs.


Didn't know they came down that much in price.

As for the part I have circled not moving, it must move to return to allowing the pressure to flow to the gun. Else it'll never develop pressure. THAT is assuming all other factors are in okay, such as the poppet valves. There are three poppet valves in the head assy. which is in that same picture. The unloader is seated in that head.
Paul


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## rick-l (Sep 16, 2009)

I have one of those and though it was broken until I relized the nozzle has a low pressure setting, it slides back and forth.


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