# Presssure washer GPM?



## GLS062866 (8 mo ago)

Good morning. When you have a second would you mind answering a couple questions on a pump that I purchased from AR?


I purchased a RVK4G37 to replace a 4G32 the finally gave out
motor is Honda 11HP
I know that motor will not give me 3700 psi but good with 3200
set the unloader to max of 3200 and works great (measured with gauge after pump before hose)
I measured the GPM and it is coming up 3.5 GPM

To reach 4 GPM do you adjust unloader to higher psi? Will engine be safe in long haul?

Or do you up in nozzle size? I am using a 4.5 right now. I assume if you do that then I would have to adjust unload to get back to 3200psi.

Without measuring to be sure is there an estimate on the draw rate of the chemical injector that is mounted after pump before hose?

Thank you for your time,
Greg


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## RH (Sep 7, 2010)

You don’t say whether you are a professional or not. But you have asked some pretty technical questions most DIYers wouldn’t be asking so for now I’ll give you the benefit of the doubt.

My suggestion to you would be to contact the customer service department of the company and speak with a rep who _*should *_have the specific knowledge about that unit to correctly answer your questions. A brief search quickly turns up a online site for AR North America (assuming you live here).


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## stelzerpaintinginc. (May 9, 2012)

The unloader should be set once and not touched again. PSI should be controlled by using various tips. GPM is a constant and will not increase by adjusting the unloader, although a misaligned unloader can lessen the GPM's, as will lowering the throttle. 

My pressure washers are plumbed to tanks, since they require more water than a spigot could provide. In my case, I'm adjusting the unloader to where I get a little trickle of bypass back to the tank while I'm on the trigger. I have a hose connected to my unloader that's plumbed back into my tank so whenever I'm off the trigger, cool water continues to circulate throughout my pump. This allows me to run it for as long as I want without having to pull the trigger and without any risk of pump damage. If your unloader is plumbed with just a loop of hose used to bypass, (like most every pressure washer you buy below 5 GPM's), then you'll need a pressure gauge and some tips specific to your exact pressure washer to properly set your unloader. Using worn tips will be bigger than new model-specific tips, which would skew your ratings and you'd end up setting your unloader too low. Using ones bought at home depot would likely be smaller than what you should be using if you have a 4 GPM pump, which means you'd end up setting your pressure at a higher rate than what you'd ultimately want, and you'll sacrifice GPM's because of it.

Feel free to give a proper introduction and tell us about yourself. If you do that, and you are indeed a professional, then I'll take the time to write out instructions on how to properly set your unloader.


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## GLS062866 (8 mo ago)

Good morning guys and thanks for the replies from RH and STELZERPAINTING. I would like to start of by apologizing if I offended anyone or misrepresented myself from the beginning. No I am not a professional in your line of work. Actually I am a pharmacist in SE Louisiana, 56 years old, married with 2 daughters , and love to hunt and fish. I am just a weekend warrior and DIY'er that enjoys doing projects and jobs myself when possible. Just as much as doing them myself I like to learn how and why thing work. Just a bad habit I guess I picked up from my father and grandfather.

I have had this pressure washer for many years and just wanted to replace a quality pump with another quality pump (at least what I thought was a good pump). Being AR doesn't make a 4G3200psi pump anymore went with 3700. No need to go to 4000 when I was told the Honda 11HP would not be able to produce it. That would need at least 13HP. I included a picture of it below. The new pump does not have the line from water filter back to top on pump. Should it?

If you have a second to discuss a couple things I would appreciate it. If not I understand and I have sent an email to AR and am waiting on a response. I enjoy reading all of these forums and came across this one is why I posted yesterday .

Without a pump pulling from a tank like you have set up I should not be letting the the unit run long without pulling trigger correct? That is because the bypass on my machine just keeps circulating the same water that heats up too much correct?

I did buy a gauge and have it mounted with quick connects between pump and hose (my understanding was it needed to be close to pump instead of at wand). Then set pressure with unloader as per AR instructions. I set at 3200 and it has a spike of about 300 when release trigger. I assume that is right before it goes into bypass. After that is when I measured the output for 1 minute (3.5 GPM) and measured chemical injector pick up as 1:11. 

My thinking which now I see is incorrect was if I went up in nozzle size to get to 4 GPM, then I assumed my pressure would go down, so then adjust unloader down to increase pressure back up to 3200. 

I guess I should invest in new tips to start off with because these are old. according to the charts I see I should use either a 4 ( chart says 3.57GPM) or 4.5 (chart says 4.1). Which one should I pick to more than anything safely run machine?

I also read where I should not be using the unloader to adjust pressure but instead use different tips and the throttle to reduce pressure?











Thanks
Greg


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## finishesbykevyn (Apr 14, 2010)

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