Air-Assisted Airless Pump Skip Spraying

Troubleshooting a "winking" problem with an AAA setup. September 26, 2013

Question
I've got a Kremlin 20:25 spray pump that is skip spraying. When the piston strokes, there is a decent pause in the spraying. I bought a rebuild kit from Kremlin and replaced a part on top of the motor that the Kremlin repairman told me to replace and put lubricant on the part that pivots on top of the motor. The repairman walked me through it over the phone but it is still skip spraying. Do you guys have any suggestions on how to fix this problem?

Forum Responses
(Finishing Forum)
From Contributor D:
Not sure, but pressure is bleeding off somewhere. Are you sure all the seals are in the correct way? Any scratches or marks in the bore? Are there nicks at the end of the bore?



From contributor G:
Also check the pickup filter if it is plugged it will cause this also.


From the original questioner:
As far as I know all of the seals are put in properly and I don't see any scarring in the bore. I was thinking the same thing about the pickup filter. I took it apart and soaked it in lacquer thinner and took compressed air and blew it out really well. When I hold it up to light I can see through it fine. Itís a #6 screen. I thought about buying another screen and see if that helps any.


From contributor G:
If you just pull the pickup filter off and try without it that should tell the tale. Also, is the gun filter clean?


From Contributor D:
Does it skip at the same spot every cycle? If so, I doubt it's a filter problem.


From the original questioner:
I thought about doing the same thing. I'm going to take the big filter and the gun filter off and run it to see if that takes care of the problem.

I was just thinking back and I do believe that it skips at the same spot every time. It seems to skip every time I hear the piston stroke. So, it may be something else causing it, Iím just not sure.

I talked to a tech guy at Kremlin and he was saying that it may be some items called Chevrons causing the problem. I've taken a lot of the pump apart but am a little hesitant about taking that particular part of the pump apart. I thought I would see if it may be something besides the Chevrons causing the issue before tackling that part of the pump.



From contributor O:
Iíve run into the same thing with my cat pump from time to time. I think my rep called it a wink but it was just a break in the spray pattern. Iíve since rebuilt the lower end of my pump and only had this happen one or two times before the rebuild. One thing I did note was that it would only wink when I had in a larger tip (513 or 516). It didn't wink with the 411 tip.


From contributor B:
Iím not familiar with the 20:25 pump but Iíve had the same problem with my 10:14 though. If they have the same type pump try taking the pump piston apart and cleaning the ball seals at the top and bottom. This worked for me the first time. It did it again several years later and I had to replace both ball seals. Also check the o ring seal where the cylinder screws into the pump.


From contributor H:
Does it stop on the upstroke or downstroke? Taking the pump apart is straightforward. Does the material stop coming out or is the spray pattern reduced in size?


From the original questioner:
Right now I'm not really sure if it happens when the piston goes up or when it goes down. I had just been watching the material coming out of the gun and when I would hear the piston stroke that is when the finish would wink. Of course that messes me up when I'm trying to spray a decent sized area. When it winks the material stops coming out for a brief second. Next time I run some thinner through it I will look to see if it happens on the upstroke or downstroke.


From Contributor L:
I'll chime in the same as Contributor B. There are two ball bearings that act as check valves. One is a large bearing about 5/16" diameter and the other is a small one about 1/8". Remove the lower pump section and clean both these up.


From the original questioner:
I have already cleaned the large ball at the bottom of the pump. I guess you guys are talking about the small ball at the end of the piston itself. I noticed that ball but have not given it a good cleaning. I will do that next.

Contributor G, I looked at a parts breakdown diagram and only noticed the large ball at the bottom of the pump and one smaller ball at the end of the piston rod. Is there another ball that I'm missing somewhere?



From Contributor L:
Just the two as far as I know. The big ball is the check valve for the major fluid flow. The small ball is for the quick return of the pump (I think).