Pressure washer nozzles, how to decrease pressure?

[great white]

My interpretation of the charts is a bit different. As I see it the lower the pressure the pump puts out the smaller the nozzle orifice has to be for the machine to reach the rated pressure. The larger the nozzle orifice allows a larger volume of water to flow through thus not maintaining enough back pressure for the pump to reach the rated pressure. A higher pressure/capacity pump can maintain the rated pressure with a larger orifice.

I'm guessing you have internal pump problems. I have 2 pressure washers. The older electric one is about the same age with close to the same pressure and volume rating as yours. It started having problems a few years ago. When I tore down the pump It was obvious what happened. Pumps of that era have ceramic coated steel pistons. Over time the ceramic wears and starts to chip off. The chips get caught in the valves and either hold them open so little pressure is developed or clog the ports. When the ports are clogged the pump reaches the overload pressure in short order. Then the motor idles down.

I ended up replacing the pump with a General like this:

https://www.generalpump.com/product/tp2021c17/?attachment_id=14660&download_file=c5025291d5f9094895be42db089785b5

At first, I thought about rebuilding the pump. I contacted General for a kit and was advised that they did have them, but I should completely disassemble the pump before ordering one. If the cylinder bores showed any signs of scoring the kit would not last long. I did as suggest and found the cylinders were a mess. Rather than throw good money after bad I bit the bullet and ordered a new pump. Unfortunately, today they cost close to $750.00 a copy. That's more than double the price of a few years ago. I'm sure you can replace the entire unit for far less.

No, it's not the pump. The overloader is doing exactly what it should be doing. Throttling the engine back with the choke stops the overloader from cycling.

This model pump doesn't have ceramic pistons or coated pistons:

All steel.

It's either the rpm of the engine or I've cocked something up with the guns somehow....

 

[great white]

Are you triggering the gun when the unloaded is cycling? Or is it when the machine is simply running standby?

Triggered. At full flow and the unloader triggers after 20-odd seconds.

The unloader valve runs constantly when the gun isn't triggered. It's designed that way intentionally. If it wasn't, when you turn off the gun the pump would just build pressure until it blew the pressure head off the case. All gas driven pressure washer unloaders work that way. Electric pressure washers don't work the same way. When you turn off the gun on an electric, the motor stops. Because the gas washer engine crank is keyed to the pump, when the motor it running the pump is turning so the unloader opens and just cycles the water through the pump rather than building pressure until it explodes. it's also why you should not let a gas pressure washer run for extended periods without flow from the gun: it will build up too much heat and kill the pump. Basically, it requires the water flow to cool the pump.

The more I think about it, the more I think my engine rpm is too high and I wasn't reading the sirometer properly when I checked it. If I throttle the engine back with the choke, the overloader valve doesn't trigger.

I've ordered a throttle assembly for the engine. That will at least give me the option of throttling back if the rpm is above 3400 rpm on the tachometer (once I get it installed). I always thought that it was odd there was no throttle on this rig, but that's the way they built it. The controllable throttle was an option on this engine from other sellers and this one even had the slot in the cover where the throttle should/would be. So I ordered one of those (was only ten bucks) and will install it in place of the fixed governor spring bracket. Worse comes to worse, I'll just leave it at full throttle like the fixed bracket would be.

Can't quite figure why the rpm is high though. This rig is set up from oem to run throttle wide open, which means it should max out at 3400 rpm. I know everything went back the way it came apart, I even marked everything, not htat there was much to mark. the throttle rod is a fixed length and the governor spring bracket wasn't even removed so no change there either and that's all the throttle controls there are on this rig.

I suppose it might be running a bit lean, which can lead to higher rpm (and possibly engine damage!). I did pull the jets and the idle screw to ultrasonic it all. basically, stripped the carb to the body. everything went back together the same. Only adjustment was the idle screw and the turns were counted and put back the same, depite the fact this thing doesn't have an idle. At wide open, the idle ciruit has minimal effect, it's essentially all main jet size at that point.

Lean is a long shot though as the plug is nice and tan....

 

[Firstram]

Weren't your original nozzles 1/4" quick connect? According to the chart, you need a #3 size, here's a full set for $10.00.
https://www.amazon.com/Tool-Daily-P...x=+3+pressure+washer+tips,aps,142&sr=8-3&th=1

 

[great white]

Weren't your original nozzles 1/4" quick connect? According to the chart, you need a #3 size, here's a full set for $10.00.
https://www.amazon.com/Tool-Daily-Pressure-Multiple-Degrees/dp/B07WVJLDXK/ref=sr_1_3?crid=29BIVY07H45BG&keywords=#3+pressure+washer+tips&qid=1702848546&sprefix=+3+pressure+washer+tips,aps,142&sr=8-3&th=1

Nope. the original gun has an adjustable nozzle:

Can't even install the old nozzle on the new gun as the attachment fittings are different.

I found some 030's on amazon.ca and grabbed 'em just in case it's not an RPM issue.

That link you posted is an "amazon.com" seller, they charge shipping to Canada (they don't recognize our "prime" account) which pretty much triples the price. Didn't see the same deal on amazon.ca.

Grabbed a 5 pack of 025's as well. the specs on the 025's match the washer a little closer without going over. Given the rig's age, it might not be delivering quite 2.0 GPM anymore (if it even did when new), so I'll have some options to play with on the nozzles.

Actually, the 030's are a little over and the 025's are a smidge under on the charts (GPM), so one or the other should work. If they don't, I'm screwed because there are no other sizes....if that's the case, I'll probably just have to go back to the original wand and just deal with it's limitations.

I'm pretty sure the engine RPM's is my issue though. I'll get it sorted one way or another.

 

[Firstram]

Nope. the original gun had an adjustable nozzle:

I found some 030's on amazon and grabbed 'em just in case it's not an RPM issue.

That link is an "amazon.com" seller, they charge shipping to Canada which pretty much triples the price. Didn't see the same deal on amazon.ca....

I didn't notice you were in Canada, bummer!

You should be able to unscrew the adjustable nozzle from that extension and add a 1/4" male plug to use it with the new wand.
Take your old handle and add a 1/4" female socket directly to the handle. A super short set-up is awesome for wheel wells and close up work!
I use this all the time!

 

[great white]

I didn't notice you were in Canada, bummer!

You should be able to unscrew the adjustable nozzle from that extension and add a 1/4" male plug to use it with the new wand.
Take your old handle and add a 1/4" female socket directly to the handle. A super short set-up is awesome for wheel wells and close up work!
I use this all the time!
View attachment 471031

Nope, won't work. The K'Archer base gun from that time sort of used the reverse of what guns use now. There's a big plastic collar that pulls the gun wand down over a fitting like a quick connect with an o-ring on it. The thread is not even common on the tightening ring. It's more like a garden hose thread than anything else.

I looked at several options and ended up just going with a new gun with the more common fittings rather than try and "bugger up" something that woudl maybe work, maybe not.

Luckily, all the main fittings on the pump are the M22 14mm fittings so the hoses and whatnot all connected easily.

 

[Firstram]

If you're talking about this kind of fitting, they are common pressure washers.
https://www.pressurewashersdirect.com/General-Pump-D10088/p2946.html

Before you toss the old gun, disassemble it and take a close look at the components. A stubby handle is handy and you can do it with what you have without spending much money.

 

[great white]

If you're talking about this kind of fitting, they are common pressure washers.
https://www.pressurewashersdirect.com/General-Pump-D10088/p2946.html

Before you toss the old gun, disassemble it and take a close look at the components. A stubby handle is handy and you can do it with what you have without spending much money.

Nope, completely different. The K'Archer "OEM" gun on mine seems to mostly be a Chinese knockoff of this MTM:

Even similar on the wand connection:

"Made in China" cast right into the plastic along with the part numbers. Probably came out of the same factory as the MTM as it's also black with the same little blue trigger block. Makes sense as the engine seems to be some kind of Honda knock off as well. Meh, whatever. It works, that's all I care about.

Old gun isn't going anywhere. I'll just keep it in storage. It's probably still going to be my preferred gun for washing the house siding. Quick back and forth from pressure to soaping and works with the "soap siphon" on the pump outlet to draw from a big bucket of 4l jug. Luckily, the gun inlet is M22 14mm, so I can put a quick disconnect on it and swap the guns around easily on the end of the pressure line. Just have to remember to turn the pressure washer off before removing a gun....lol!

Don't need a "stubby", essentially already have one.

Gun I purchased:

Foam cannon:

All quick connects for the nozzle portion so I can either use the gun with the long extension and pop the tank off the foam cannon an pop in a nozzle when I want.

I prefer the longer wand for rinsing though. Give me a more balanced feel and a "forestock" to hold on to if I want. I also prefer to be further back from the mist from the nozzle and "stand off" from the vehicle a bit more. just personal preference is all it is.

I bought those particular products because they both use the same gun portion. If in a pinch, I can use one for parts for the other or just swap one for one.

Also, after the first gun showed up, I was surprised at the quality feel it had for the price, so I bough the foam cannon too. Never had one, thought I'd try one. Same gun, same quality. Sure, the trigger pull is perhaps a little heavy , but it's not an MTM gun, which would be 3-4 times the price and with no accessories. For the price, I'm happy with it.

Just have to sort out the "overloader/RPM" issues....

I also grabbed these while I was at it:

and:

And a couple sets of:

Then for the foam gun, some 1.1mm nozzles:

And because my broken back and neck make it hard to reach the bottom of the wife's van and the top of my truck:

Figured "in for a penny, in for a pound". Even if I did save some bucks with "import" stuff. Worth it just to rinse the salt off the vehicle's undercarriage once or twice a week.

I'd already bought one of these:



So I just roll it all in and out of the heated garage as needed. As long as the sun is shining and it's not too cold, the water evaporates right up off the asphalt so getting the winter salt off the vehicles at least once a week is worth the effort.

It's all working great so far, so no complaints other than the pressure washer itself needing more sorting. No leaks, everything fits together fine. A bit surprising really......we'll see how it all holds up over time though.

 

[CJ5Dave]

Nozzle does not generate pressure. Pump does. I assume when the pump is running you have the trigger pulled. Gas pressure washers are not made to cycle. Electric ones can cycle off when trigger is not pulled. There is usually a pinpoint nozzle, next a yellow one, next a green one, next a black one lower pressure to siphon soap). Then maybe a spiral one. The green one will have larger orfice, less back pressure, probably still all the cleaning force you need. With the pinpoint one you can write your name in your auto paint.
I bought a Craftsman washer at a yard sale. It had a cluster type turret nozzle. 5 in one, the whole thing quick attached to the wand.

 

[pontiac428]

Kärcher is a German company that primarily specializes in pressure washers and vacuums. They do have manufacturing in China, but they aren't a knockoff, they are a true-blue product designing entity. I wouldn't be cluttering up your thread for any other reason but to point out that Kärcher is notorious for using proprietary threads and fittings on their kit, forcing you into their ecosystem following the Apple Computer business model. As you plod along finding whatever works, just keep that thought in the back of your mind. The upshot is they sell spares and provide diagrams with part numbers.