Problems with HVLP gun...Help!

[chris del]

I have a Leemer A-928 HVLP gun with 1 gallon pot. I have only used it a few times, then last time being a month ago with oil based poly. I ran paint thiner thru the gun after using the oil poly and put it away.
I had a whole bunch of stuff to spray and because it was so warm today I decided to get the gun out. I put some water based poly in the pot (straining it of course) and the gun would not function. Very,very little poly would come out. I took the gun apart, taking the needle out and cleaned the whole thing. After I put it together I still had the same problem......
I know very little about spray guns and I am a little frustrated, afterall this is not a low end gun......
Please help!!!

[Tim Sproul]

Did you check the fluid pressure? Any leaks anywhere?

I'm often changing the regulator on my compressor because I'm shooting finish at one point or firing nails at another. Are you feeding enough pressure into the pressure pot?

Did you strain the water based poly through a medium mesh or finer filter?

When you cleaned your pressure feed hoses...did you clean them or just shoot a bit of solvent? A lot of finish will adhere to the hose walls....which requires a bit of agitation with solvent in the hoses to remove. The finish could have flowed to the low points in the hose and is clogging the hose...or bits of cured oil based poly are flaking off the inside of the hose and clogging the gun. For my pressure feed hoses, I fill partially with water/solvent and shake shake shake and drain. I repeat several times. Since my finishes are all water based/borne finishes, I only use water and then dry out the hoses with alcohol.