# Upgraded Backpack Sprayer Pump



## Kicker (Apr 5, 2018)

I went full "Tim the tool man" on my backpack sprayer this weekend. I do not advocate tearing into your backpack sprayer and changing the pump. The sprayer i have (My 4 sons) specifically designs their sprayers for ease of replacing every component in it and offers these components at reasonable prices should you need to replace them.

I was disappointed with the original pump due to spray time (for 1 gallon) getting longer and longer and longer and while i could have replaced it with one from My 4 Sons; I wanted something with more gpm so i can have the capacity to put multiple TeeJet nozzles on a boom. I went with the Northstar 2271T pump from Northern Tool & Equipment.

This pump is physically MUCH larger than the original so some outside-the-box thinking and some gentle modifications had to be made in order for it to "fit" into the sprayer.

Pump comparison (new pump on the right): 


New Pump and Existing Battery: 


I had to cut a large hole in the plastic for the pump to stick out of so i could close/seal up the sprayer base and keep everything hidden, for the most part. The new hoses for the pump took up way more space than i was intending and i had to get somewhat creative with elbow joints and right angle adapters to allow enough room for the battery and hoses to coexists.

Internal configuration and management: 


Final setup: 




So far i can estimate it's putting out about 60 psi per the time it took to distribute 1 gallon using the XR and AI 11104. It matching up to the spec'd output per teejet for those nozzles

The only downside is the run time has drastically reduced due to the battery size and increased draw of the larger pump.


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## pennstater2005 (Jul 17, 2017)

That's pretty ingenious! Great job :thumbup:


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## Ware (Jan 28, 2017)

Nice work!


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## stotea (Jul 31, 2017)

Ha, awesome. I considered doing the exact same thing with my backpack sprayer (also an M4), but I ended going all out with a push sprayer + boom.


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## LawnRat (Mar 22, 2019)

Nice work! You could look into a 12v lithium-ion battery pack to bump the run time back up while keeping the size the same or less.


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## Christech11 (Mar 26, 2019)

When you build your boom how many nozzles are you planning to use?


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## FlowRider (Apr 7, 2019)

And I bet the vibrations from the pump give you a lower back massage while you spray your yard...! :lol: 

I have seen a lot of shade-tree engineering done on this forum, but this is one of the more well-executed upgrades I have seen yet. You can hardly tell you changed anything, except for that big motor sticking out in the breeze in the back.

I like it. Now you just need to rig up some hot swappable battery changeout setup, and you can knock out your spraying!


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## JWAY (Oct 16, 2018)

Well done @Kicker 
Interested in what the boom looks like when you get it done. The prototype M4S sent me isn't cutting it.


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## Kicker (Apr 5, 2018)

Christech11 said:


> When you build your boom how many nozzles are you planning to use?


Just 2 nozzles, i only have 5k sq ft and some of that space is pretty narrow.



LawnRat said:


> Nice work! You could look into a 12v lithium-ion battery pack to bump the run time back up while keeping the size the same or less.


I'll look into that, thanks.



JWAY said:


> Well done @Kicker
> Interested in what the boom looks like when you get it done. The prototype M4S sent me isn't cutting it.


It's the same one i would imagine. It was a bunch of pieces that you can configure in different ways depending on how many nozzles you want. I opted for only a two nozzle boom because well i'm only spraying 5k sq ft. I followed some of the advice you gave me in a PM and cut the piece between nozzles to length so that the nozzles would be 20" apart and am just running with that.


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## JWAY (Oct 16, 2018)

@Kicker 
Your recent post reminded me of this build you did. Where did you source the barbs and MPT/barb fittings?
Were there any other parts you had to purchase besides the barbs and hose?

I'm needing more oomph from the M4S so I can spray my roof for mold without having to get up on the roof. 
Thanks


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## Kicker (Apr 5, 2018)

JWAY said:


> @Kicker
> Your recent post reminded me of this build you did. Where did you source the barbs and MPT/barb fittings?
> Were there any other parts you had to purchase besides the barbs and hose?
> 
> ...


I got all the fittings MPT/barb and barb/barb at Ace Hardware. There selections of fittings and sizes is way better than what i found at Home Depot. The tubing I got from Home Depot although I think I remember seeing it at Ace Hardware as well.

I did not need any other parts with exception of some additional hose clamps for all the extra fittings. Just read what the recommended inlet tubing size is for the pump and get the appropriate fittngs and tubing.

Everything is is pretty much straight forward with the exception of getting it all to fit. I had to switch the locations of the pump and battery from it's original configuration and it's still a really tight fit. Also had to cut a hole in the plastic housing to allow part of the pump to protrude from.

It's a huge improvement for a relatively low cost investment.

Oh, BTW. Trying to use this with the "boom" that was sent from M4S was a disaster. The pressure from the new pump literally blew the boom/wand apart at the connections. i'd press the trigger on the wand and the boom shot off the wand a good 3 feet.


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## Johnl445 (Feb 11, 2020)

@Kicker just curious, How long was your run time with the original battery and did you ever upgrade to a lithium ion battery.


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## Kicker (Apr 5, 2018)

Johnl445 said:


> @Kicker just curious, How long was your run time with the original battery and did you ever upgrade to a lithium ion battery.


I never upgraded the battery, just the pump.I never tested the max run times with the old pump. The new pump gives me probably 1.5 to 2 hours run time I'd guess. I can do multiple full coverage applications on 5k sq ft without having to charge it.


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## ScottieBones (Apr 2, 2020)

Nice work! If you are still able to get enough run time to finish the job, then that sounds like it's worth the upgrade in flow.


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## BobLovesGrass (Jun 13, 2020)

You upgrade seeems very well done, thank you for sharing a nice plan.

That said, I wonder if higher battery voltage could have been used with the small pump, like the 19.2volt Craftsman cordless tool batteries or something like that?
Just kind of thinking out loud. I am trying a small pump upgrade on my towable sprayer this year, heck maybe I can try the higher voltage on the old pump first, that way if I roast it no loss.


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