Odd 3PT sprayer problem

[sixdogs]

I have a typical 3PT 60 gallon sprayer with a standard PTO roller pump and have a problem I can't figure out. At times, no spray comes out because no fluid is making in up into the lines.
I can see the fluid trying to pump up to the "sprayer control valve"

DIRECT-O-VALVE, NYLON - Agri Supply

where the gauge mounts, but I can see it falling back by viewing through the opaque fitting.
I discovered that if I disconnected the rubber intake hose at this control valve inlet, it would pump water out--and when I reconnected it, things worked fine. It was only after the sprayer sat for a couple days that it failed.
So I thought I had a bad pump and bought a new one. Nope, no change.
Maybe bad sprayer rubber hose so replaced those. Nope.
Tried a new filter assy thinking it was sucking air. Nope.

So I'm left with one of two choices--I think. It's either this simple sprayer control valve or maybe the pressure regulator

3/4PRESSURE RELIEF VALVE NYLON (250 PSI - Agri Supply

that mounts in-line after it. Neither of these seems like the problem but I tried all else.
Any ideas or guesses helpful--I'm stumped.

 

[sixdogs]

Any guesses on this? I'm stumped.

 

[jake98]

Is there a motor with a coupler?

 

[David_Kb7uns]

Do you take pump off and drain and fill with oil or antifreeze after each use? If not most likely there is rust on the rotor and the rollers are jamed or have defects in them and are not sealing the pump and it is just spinning and not moving fluid. If it does this with a new pump you may be air locked, and need to open up the pressure relief valve so that the flow is returned to tank and purges the air as these pumps need liquid in them to prime. Once primed the pressure can then be increased and I can get over 60 PSI no problem. Also some sprayers do have a screen and a shutoff under the tank and they do break or the suction hose will leak and suck air and then not build pressure. Hope this gives you a direction to check.

David Kb7uns

 

[hawkeye08]

My brother is experienced in this area and over the recent holiday, I asked him about buying a used sprayer..

First he said, they do NOT survive when run dry. He told me to make sure that pump was flooded before it was engaged (He has had to repair more than a few where someone routed the pickup hose such that the pump ran dry trying to pull liquid. He stressed to me that the pump needed to be low spot and not to run until tank was dry but rather shut it off before it got there. Wasting a little bit of spray mix is cheaper than replacing the pump. I asked if it ran dry unintentionally, how much would it take before it was damaged. He said it does damage right away, the longer it runs dry the more damage it does. Apparently the clearance inside with the rollers must be pretty tight tolerances.

Of course, now I am over cautious about buying used and have not purchased sprayer yet (I have 30gal tow behind with wand, but want 3pt with boom and wand). I figure that if I buy a used sprayer, I will need to budget to replace pump since I won't know the accurate usage history...

 

[beersngars]

Did you check the strainer? That's what it sounds like to me. I have a Fimco 60 gal and it's strainer does trap some crap.

 

[sixdogs]

Thank you. It is a 60 gallon Fimco and the the strainer is always clean. I am a bug on doing things right and the pump was never run dry. But just for the heck of it I replaced the strainer assy figuring it must have a crack and was sucking air. Nope, same problem. So I figured the pump was bad and put a new one on. Nope.
Then I discovered that if I disconnected the output hose off the PTO pump and ran some water on the ground and then reconnected it, all was good and it would pump fine. So I figured the hoses were bad and sucking together so I replaced them and still no go.
It will pump Ok if I disconnect that exit hose and run water on the ground and will work for a couple of days. If I let it sit too long it won't pump until i disconnect the hose again. I really am confused.
So now do I freplace the "pressure regulator" valve I referenced above or maybe the "direct-o-valve"? that's all that's left to go but maybe one if you guys can offer a guess?

 

[BillBeyer]

Mine does the same thing at times. I think it air locks. I remove the hose just like you stated and I am good to go.