Troubleshooting a Stalled AAA Pump

Coming to grips with a pump malfunction in an air-assisted airless spraygun rig (it was the magnet). January 12, 2015

Question (WOODWEB Member) :
I use a C.A.T. H20, AAA and have been very pleased with it, no troubles until now. The pump has stalled at the top of the stroke and blows air out of the vent on top. I can call a rep in the morning but I would appreciate someone clueing me in.

Forum Responses
(Finishing Forum)
From contributor X:
Try turning up the pressure, once in a while I need to do that with my Kremlin to get it to turn over.

From contributor G:
Yep, my Kremlin will do that when using low pressures or high viscosity materials. Crank the pressure, sometimes you need to turn the air on and off really quick if the higher pressure won't kick it over.

From the original questioner:
I tried raising the pressure, up all the way, turned the shot off valve on and off. Still just blows air out of the top of the air motor. I got it to cycle by covering the vent holes on the top of the motor (cover off) but it wonít cycle fast enough to build pressure for spraying, it is leaking air. I've ordered a set of o-rings for the motor and an upgraded anti-stall magnet for the trip rod. The material I'm spraying, GF white undercoat, is very high viscosity. I've only sprayed twenty some gallons of the stuff. It has sprayed great, with about fifty pounds of input air. If it sprays nice and lays out nice I shouldn't have to thin it right? I spray mostly clears but this stuff is what gave me trouble. Does anyone else spray much heavy material with a 14:1 pump?

From contributor H:
Itís most likely the magnet that helps trip the pump on the change of the stroke has loosened. Pop the top cover and you will see two wrench flats and tighten. If that doesn't go, call their 800 number as they have great tech support and will get you up and going.

From the original questioner:
Problem solved. It was the magnet. The face plate on the bottom of the magnet came loose and extended past the o-ring, hence the air leakage and the stalling at the top of the stroke. The C.A.T. tech person I spoke with was very helpful. It turned out to be an easy fix. Thank you everyone for your input.