Troubleshooting AAA spray rig

[phmade]

I've been spraying with a CA Technologies AAA rig for a while.  (It's an H20 14:1 with bobcat gun).  I'm normally spraying Target Coatings waterborne finish through it and I've had great luck although I'm definitely still learning.  A couple days ago I needed to spray some shellac and I used the AAA rig instead of my gravity gun because I had alot to do (about 2 gallons).  After cleaning the lines with denatured alcohol and then flushing with distilled water, I can't get the pump to build up pressure.  I disassembled and cleaned the gun and lines.  I didn't really see any problems.  This morning and I disassembled and cleaned the fluid section of the pump.  I found a couple areas with dried finish around the ball check valves and cleaned them so both are operating freely.  After re-assembling, I expected it to work well.  Still not building pressure. 

I disconnected the siphon tube and hose and simply held a bucket of water under the fluid intake.  It pumped it up and had good pressure.  I'm guessing that my siphon tube/hose has a leak in it but I certainly can't find it and I've tried pressurizing it with air to find a leak.  I can't seem to find any.  Granted, my air pressure is only about 90psi whereas the fluid pressure it typically 350.  Am I missing something?  Does anyone have any thoughts?

I think I'm gonna go purchase a few fittings and section of hydraulic hose to test it.  If that works, I'll just order a new siphon tube assemble on monday.  I'll report back.  Off to the store on black friday - this should be fun... 

Thanks!

 

[phmade]

I'm reporting back with no success.  I made up another siphon hose and that did not work either.  All signs are pointing to a failed seal near the lower ball check valve.  I think I'll order a rebuild kit on Monday.

 

[tjbnwi]

I recall certain pumps not being able to take any types of solvents due to the seals. They were designed for water bourne only. Not sure if it was C.A.T. pumps or Kremlin.

Tom

 

[phmade]

Hm - I'm thinking that might be the case since I had only sprayed waterborne though it previously.  Although - I thought my distributor told me I could flush it with Denatured alcohol.  I'll talk to CAT on monday to get the real answer.

 

[Scott B.]

I'd try a different fluid hose to rule that out as well.

 

[Oldwood]

Does the gun have a screen filter where the hose connects to the gun? I use a Kremlin and it does have a screen that can get plugged and cause the sort of problem you describe.

HTH
Gerry

 

[phmade]

Ok, problem solved. It turned out to be vapor lock. I spoke with CAT today and the told me how to manually prime the pump. Not sure why this happened but at least I know about it. They said it was rare but it does occasionally happen.