Running a larger DS Injector (5-8 GPM) on smaller pump (2.5 GPM)

Newbie here and this is a very difficult thing to search for.

My local supply store only carries the larger 2.3(mm?) for 5-8 GPM pumps. I wanted to get 1.8(mm?) for 2-3 GPM pumps to use for my 2.5 GPM machine. The store claims “it’ll still work”.

My question to this community is, will a 2.3 DS Injector draw more than 1.8 DS Injector on 2.5GPM pump? Will I need to account for this in my batches? I guess the only real to know way is to perform a draw / bucket test for injector and pump output?

It will draw less. I would go somewhere else as they don’t know what they are talking about. Not that having a local supplier still won’t be a good thing, but I wouldn’t ask them for advice!

Or not at all. Especially if you’ve got more than like 10 feet of pressure hose. Any amount of back-pressure is going to stop that large injector from drawing.

Also, 2.5 gpm is tiny. Find some way to upgrade to at least a 4 gpm machine.


It’s only $15 to tinker and find out

They sell them every day on

1 Like

Heck they even sell them on Amazon.

Thanks for responses. I bought local to support local. I’ll tinker and report back my findings here.

I’m a part time solo operating lawn guy and I have passed too much on “do you do pressure washing?”. I’m focusing on offering it in 2022 but I need to work my finances to determine what 2021 deductions (budget) I need to take. I am eyeing a 5gpm if the tax man will allow it (on top of my current lawn equip).

For now, I’m researching and testing with what I have (2.5gpm). For my own house, I normally just manually house wash mix with pump sprayer, but I want to try DS injecting with my current setup.

That’s great, but if you can’t get what you need locally then it’s time to order online.

1 Like