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Help with Lesco sprayer


LawnSite Senior Member
I'm licnesed and laggit just to make that point off the bat however, for the last 2 years I used Granular Herbicide and now you guys talked me into using liquid herbicide I bought a used lesco sprayer/tank that was in awsome shape even the guys at lesco said it was good to go. But... I'm having problems with the pressure when I got to spray I let it agitate for a bit then slow down the shut off valve about 70-80%. when i hit the trigure pressure builds up and gives me a good strong jolt of water then the pressure comes back to normal any ideas or advice I'm really nurvous about using liquid herbicide and scared to death of burning any lawns, I guess just easily intimadated on this one... :confused:


LawnSite Senior Member
You should be able to adjust your regulator to solve this, but i have 3 of these units and one of them does exactly the same thing. It is something that i have learned to deal with just make sure you are moving your hose end at the same time you pull trigger, i have been using liquid apps for 15 or more years and never burned a yard yet.


New Jersey
Sounds to me like your pressure is too high. With gun closed, pressure should be below 50 PSI at the pump. For herbicides it's a good idea to spray with the lowest PSI possable, while still maintaining a good spray pattern.

I prefer the Lesco/chemlawn gun with the blue nozzle for herbicides when dragging a hose.....Works well with low pressure.

Enjoy the new sprayer,

Pete D.


LawnSite Silver Member
S.E. Michigan
Sounds like the pressure setting is set too high on the pressure relief valve. You may have to adjust it lower to get the right pressure for whatever GPM nozzle you are using. This may take some time (trial and error) to get it set correctly.


LawnSite Member
Sw Missouri
I don't know what kind of pump you are using, but make sure you have enough air pressure above the diaphram if it is a D30/D50. Mine did the same thing.