Need help on DS

I have a 5GPM machine, and just got a new 8GPM, I was trying to set up the DS system today, but failed.
Here are some tests I have done.

  1. #2.1 injector (BE brand), on the 5GPM machine, draws about 1/16 soap with a 0040 tip. Stop pulling soap with a 0015 tip, around 300psi. Working as expected.

  2. the same #2.1 injector (GP brand) on the new 8GPM machine draws 1/30 soap with a 0060 tip, continues to draw 1/60 (approximately) soap with a 0020 tip, around 1000psi (on gauge), stops drawing soap with a #6.5 tip, around 3000psi.

  3. #2.3 injector, on the 5GPM machine, draws 1/12 soap with a 0040 tip. Stop pulling soap with a 0015 tip, around 300psi. Working as expected.

  4. the same #2.3 injector, on the new 8GPM machine, draws 1/23 soap with a 0060 tip, continues to draw 1/50 soap with a 0020 tip, around 1000psi, stops drawing soap with a #6.5 tip, around 3000psi.

  5. did the bucket test, the 8GPM machine actually did a little over 9 gpm.

I am very frustrated, why is it still pulling soap at 1000PSI??? Why the ratio is so low?

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With my 8 using 2.1 3-5 gal injector I get about 1/18 soap. I just use a m5ds nozzle though for soaping and rinsing with a rare exception I use a shooter tip which pulls the same. There’s a reason that 99% of us using an 8 have a soap cutoff, either mechanical or electric. I’ve never measured how much pressure it takes to cut off the soap with a tip, because whatever it is, it’s too much to be rinsing a house with.

Do you have your injector mounted near your reel? How many feet of hose you testing through? What do you get when you use the black soap tip that came with the machine? Have you got a pressure gauge? What size trigger gun are you using? All of these can affect your numbers.


First thing I would do is test your draw rate at the end of your hose, whatever you usually use, with no trigger gun and see what you’re getting. If you have a pic of your setup, that may help.

Hello Rick, thank you for always answering my questions.
I didnot know that 8gpm doesn’t work like a 5gpm, and needs a soap cutoff. I guess I will just run back to my truck a lot.
I have a 4ft jumper hose going from PW outlet to the injector, and then to the hose reel. I tested 200ft hose and 50ft hose, same results. The machine doesn’t come with any tips. I test with open (no gun, no tip), and with just gun (no tip), and with 0060 tip. All the same results. I do have a pressure gauge, it reads 0 on a 0060 tip, and 1000PSI on a 0020 tip. Trigger gun is rated at 10.5GPM.

What confused me a lot was the same setup works flawlessly on a 5GPM.


Splice a gray 1/4 inch valve on your chem draw line. Then open when soaping and close when rinsing. This also prevents air from
Entering the line when rinsing with a soap tip.


Sounds doable.

That’s what I have, a little ball valve on the chem line. My wife and I communicate by radio.:+1:

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After knowing soap doesn’t stop around 300psi on an 8gpm, I guess that’s what I will do.
But, any suggestion on how to pull more soap? 1/23 is not going to clean, I believe.
According to my tests, the same injector did pull 1/12 on a 5gpm.

I use the exact same setup on my 4gpm and 8.5 gpm. I have whip line coming from each and I just plug whichever I want into my injector. The 4 pulls about 1/9 so your 5 pulling about 1/12 is right on. on my 8, like I said I get around 1/18. 1/23 not terrible, you’ll just have to use pretty much straight SH with your surfactant. Will clean most things since I usually dilute mine a little anyway unless really bad. If so I’ll just soap with my 4 the bad spot and then plug in my 8 to rinse and do the rest of house, but that’s really rare I have to do that. You can play with the inserts on your injector to draw more soap.


Hi Rick, I tried today with the 8gpm, DS straight 12.5% SH. Did not clean very well, had to redo some areas. Ended up soaping with 5gpm, and rinse with 8gpm. BTW, Loved my new 8gpm :grinning:

By “play with the inserts”, do you mean drill a bigger hole? On the soap-in end, but not the water-in end, right? I never did it before.
I never did a lot of things, being a new guy :joy:

Some ds injectors have inserts just like the x-jet.

Thank you, DJ. I use General Pump injector from PressureTek. #2.3 for 5-8gpm. It doesn’t have any insert.

Use a 3-5gpm injector.


It should have a changable orfice . If the part number on the injector is 100778. It will be on the source side and it should take a 5/32 Allen wrenches. Just order some 3-5 gpm orfices. U can also order some ceramic ball rebuild kits while ur at it that comes with a good spring and a viton oring. U need an unloader block and I would change out that unloader to a k7. Then the ball in ur injector won’t slam against the oring Everytime after u let off the trigger after applying soap and putting unneeded pressure on ur equipment.

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What model is ur pump? U will want to change ur hose feeding ur pump to non crush and take out any 90s if u can.

Please forgive me. The #2.1 injector (BE brand) is for 3-5gpm machines, and it pulls less soap than the #2.3 one (General Pump brand).
I am guessing, theoretically, #2.1 should draw more soap than a #2.3 one? But BE is not building a good injector?

Thank you very much for your detailed instruction, Christopher.
Lots of new info for a new guy like me.
Just googled unloader blocks. Funny thing, I have a very interesting 8gpm. it comes with two outlets, and two unloader blocks I can play with.
Where do you buy 3-5 gpm orifices?
I found a lot of K7 unloaders. Being a guy who just heard about unloader blocks and K7 unloaders, I have no idea which one to choose…

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This is the machine I have

Comet Triplex Pump - 8gpm 3000psi - [External Unloader Valve]

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If you are running 200 ft of hose you need a 2.1 to get enough back pressure to pull soap. Anyplace that sells a 2.3 will sell a 2.1

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