The Three C's Of Spray Gun Troubleshooting: Condition, Cause, Correction
How Does Your Spray Gun Shape Up?
The information below provides you with a simple and effective method of tracing problems with your gun if it proves troublesome. Look down at the left hand “Condition” column until you identify the problem and you will find the possible “Cause” and “Correction” that needs to be taken. There is also a diagram of a paint spray gun below to help you visualize where to address the problem on the gun.
| Condition | Cause | Correction | |
| A | Will not spray | No air pressure at gun | Check air supply and air lines |
| Fluid needle adjusting screw not open enough | Change to proper suction feed air cap | ||
| Fluid too heavy for suction feed | Increase fluid pressure at tank | ||
| Open fluid needle adjusting screw | |||
| Thin material or change to pressure feed | |||
| A | Gun spits paint when triggering on and off | Incorrect needle fitted to gun | Check tip/needle selection chart and fit correct item |
| Excessive needle wear | Replace with new needle | ||
| Excessive fluid tip wear | Replace with new fluid tip | ||
| A | Small air leak from air cap when gun is not triggered | Air valve contaminated and not correctly sealing | Remove valve and thoroughly clean valves shaft and seating |
| A | Gun spits paint when triggering on due to paint build-up inside air cap between spraying operations | Fluid tip not fitted correctly in gun head | Tighten to correct torque |
| Fluid tip/needle leakage | Check for damage or blockage | ||
| A | Slow fluid leak from fluid tip and needle seat | Fluid tip internal seat scored, damaged or worn | Replace |
| Fluid needle external profile damaged or worn | Replace | ||
| Contamination on needle or tip mating surfaces preventing good seal | Thoroughly clean | ||
| Incorrect fluid tip for fluid needle fitted to gun | Check tip/needle selection chart and fit correct item | ||
| Sluggish needle | Remove needle and clean or lubricate packing | ||
| Tight packing | Adjust | ||
| B | Slow fluid leak from fluid tip and needle seat | Fluid tip internal seat scored, damaged or worn | Replace |
| Fluid needle external profile damaged or worn | Replace | ||
| Contamination on needle or tip mating surfaces preventing good seal | Thoroughly clean | ||
| Incorrect fluid tip for fluid needle fitted to gun | Check tip/needle selection chart and fit correct item | ||
| Sluggish needle | Remove needle and clean or lubricate packing | ||
| Tight packing | Adjust | ||
| B | Major fluid leak or fluid jetting from fluid tip | Contamination of needle or tip mating tip and needle seat | Remove tip and needle and thoroughly clean surface preventing good seal |
| Incorrect fluid tip for fluid needle fitted to gun | Check tip/needle selection chart and fit correct item | ||
| Fluid needle stuck or "binding up" | Remove and clean fluid needle shaft | ||
| Lubricate needle packing | |||
| Loosen needle packing | |||
| B | Paint build-up on fluid tip | Fluid tip not fitted correctly in gun head | Tighten to correct torque |
| Fluid tip/needle packing worn or loose | Check for damage or blockage | ||
| C | Slow fluid leak from needle packing | Fluid needle packing worn or loose | Tighten or replace as necessary |
| D | Air valve sluggish or slow to turn on/off when trigger is pulled/released | Air valve stem bent | Replace damaged component |
| Air valve seal damaged or missing | Replace | ||
| D | Air valve will not operate (air valve stem will not fully slide into valve body) when trigger is pulled | Air valve stem bent | Remove air valve And replace damaged air valve stem |
| Contamination on air valve stem | Remove air valve and thoroughly clean | ||
| E | Stiff trigger action | Air valve stem bent | Replace damaged component |
| Contamination on air valve stem | Remove and clean | ||
| Contamination on trigger bearing screw | Remove and clean | ||
| Contamination on fluid needle shaft | Remove and clean | ||
| Fluid needle packing too tight | Loosen packing nut | ||
| F | Air leak from fluid needle exit point in top of handle | Seal damaged or missing | Replace |
| G | Air cap retaining ring will not rotate | Contamination on retaining threads | Soak gun head in solvent to soften paint |
| Deformed or damaged retaining ring | Cut retaining ring off of gun (probably replace retaining ring and baffle as well) | ||
| H | Unable to turn fan control knob on top rear of gun | Internal o-ring swollen or broken | Replace o-rings |
| Paint contamination on threads | Remove and thoroughly clean | ||
| H | Unable to get round spray | Fluid tip or air baffle incorrectly fitted | Remove, check components for damage and refit correctly |
| Air baffle chimney damaged | Replace air baffle | ||
| I | Air leak from baffle seal | Baffle seal swollen or damaged | Replace |
| J | Unable to turn air control valve on handle of gun | Internal o-ring swollen or broken | Replace o-ring |
| Paint contamination on threads | Remove and thoroughly clean | ||
| K | Paint build-up on air cap | Damaged air cap holes | Replace with new air cap |
| Gradual build-up of bounce-back on gun head | Thoroughly clean |