Craftsman (Briggs & Stratton) pressure washer not sucking

[DGersic]

I have this Craftsman pressure washer that seems to have been made by B&S.



There is a clear vinyl hose that can be attached to the pump to provide a soap spray at low pressure.



This isn’t working. It has worked in the past. Having taken it apart, now I’m trying to understand how it is supposed to work.



The fitting for the soap injection hose (J) is shown here as (G) and consists of a brass fitting, some sealing O rings, a bit of plastic, and a checkball and spring.



What is tripping me up is that the fitting (G) is on the output side of the pump. It would seem to be always under pressure, because the water flowing through the pump is always under pressure. Even with the engine not running, water pressure in the input hose is going to stack up against the wand orifice.

The checkball is set up to allow fluid flow in, prevent flow out. If I remove the checkball, I get water coming out of the fitting. With the checkball in place, I get no water coming out, but I also get no suction at the fitting.

This is supposed to only flow soap at low pressure, shutting off when the wand is switched to high pressure. So it must be flow / pressure sensitive. Is there supposed to be enough water flow at low pressure to generate a venturi effect, providing enough suction to overcome the spring on the checkball? Or is there some other mechanism at work here?

 

[finn]

Venturi effect. Liquid flowing at high velocity past the small port creates a low pressure region (vacuum) along the passage wall, which ***** the soap into the flow.

Consider that the velocity profile across the passage cross section is bell shaped, with very low velocity along the wall and high velocity at the center. It’s sucking along the wall, where it’s ported to the dispenser..

Look up fluid flow in a pipe, or something like that.

Basic fluids / fluid dynamics principle.

Good question though.

Ps: mine doesn’t work either. I suspect the tiny orifice is plugged.

 

[Motown]

Can you just use a foam cannon?

 

[mikegt4]

It's been a long time since I used the soap application feature on my pressure washer, mostly due to the fact that it uses soap at a tremendous rate. That being said, I found that it only works when not using high pressure flow unlike pressurized water/soap at a self serve car wash. Yours may be different but try it once running without using high pressure, just a gentle application of water/soap. My pressure washer has an adjustable pressure knob.

 

[vwpieces]

This is supposed to only flow soap at low pressure, shutting off when the wand is switched to high pressure. So it must be flow / pressure sensitive. Is there supposed to be enough water flow at low pressure to generate a venturi effect, providing enough suction to overcome the spring on the checkball? Or is there some other mechanism at work here?

on my PW i need to swap the nozzle for the one with the largest hole for the soap to **** out of the bottle.

 

[kctgb]

Do you live in a state that has temperatures drop below freezing? And did you run RV antifreeze through it before winter?

 

[vwpieces]

Oh, just saw in first pic you have the adjustable nozzle fixed to the wand. Not a fan of those.
I have swapped all of those out to wands with quick connect nozzles, properly sized to the machine output.

 

[larry4406]

My Cambell Hausfeld is also B&S and my soap dispenser doesn’t work, but it did when new.

So I’m following along.

The wand tip on mine has a push/pull on it that would adjust unit to low pressure to **** detergent.

 

[firebirdparts]

I don't know much about these things, but I know the soap nozzle is mostly a big hole so your discharge pressure is "low". It has to be "low enough" for the soap sucker to work.

 

[Hohn]

on my PW i need to swap the nozzle for the one with the largest hole for the soap to **** out of the bottle.

This is necessary for the discharge pressure to drop low enough for the venturi effect to work.
There is no venturi effect on the soap dispenser at 2000 psi or more. Quite the opposite-- hence the check ball.

 

[DGersic]

Venturi effect. Liquid flowing at high velocity past the small port creates a low pressure region (vacuum) along the passage wall, which ***** the soap into the flow.

Consider that the velocity profile across the passage cross section is bell shaped, with very low velocity along the wall and high velocity at the center. It’s sucking along the wall, where it’s ported to the dispenser..

Look up fluid flow in a pipe, or something like that.

Basic fluids / fluid dynamics principle.

Good question though.

Ps: mine doesn’t work either. I suspect the tiny orifice is plugged.

Thanks. I thought it had to be Venturi, but confirmation helps.

I know that it used to work, when new. Can’t say it worked all that well, but it worked. Then it didn’t. Knowing I was going to need it, I futzed with it a couple weeks ago, and it was working again. Then tried it last week, and it’s again not working.

Seems to be very sensitive to getting exactly the right flow.

 

[DGersic]

Can you just use a foam cannon?

Probably a better idea overall, but I didn’t have one last week, nor the time to go buy one. So now it’s a challenge to get it working correctly.

 

[DGersic]

It's been a long time since I used the soap application feature on my pressure washer, mostly due to the fact that it uses soap at a tremendous rate. That being said, I found that it only works when not using high pressure flow unlike pressurized water/soap at a self serve car wash. Yours may be different but try it once running without using high pressure, just a gentle application of water/soap. My pressure washer has an adjustable pressure knob.

Yes, it’s only supposed to work at low pressure.

This one doesnt have an adjustable pressure knob. The pressure is set by the wand. It has a push/pull end to switch between high and low pressure.

 

[DGersic]

Do you live in a state that has temperatures drop below freezing? And did you run RV antifreeze through it before winter?

Yes, we get well below freezing here in Illinois.

No RV antifreeze. I do run Craftsman (Briggs) “pump saver” through it before storage though.

 

[DGersic]

My Cambell Hausfeld is also B&S and my soap dispenser doesn’t work, but it did when new.

So I’m following along.

The wand tip on mine has a push/pull on it that would adjust unit to low pressure to **** detergent.

Sounds like Briggs sold this design under several brand names.

 

[ATC]

I have a Troy-Bilt (I think) with a B&S engine on it and the soap dispenser hasn't worked since day one.

 

[Hohn]

They did you a favor, you don’t want to use them anyway.

 

[DGersic]

Today, I took off the suction inlet, and the pump output (C) and stared at the parts labeled (F) that are down inside the pump with no clear way to extract them without damage.

Looking in to the suction inlet, it appears to be blocked by a white plastic piece, I’m assuming part of (F). I see no orifice or any other way for anything to get in here.



So, maybe the foam cannon is really just the best answer at this point.