Bostitch BTMT72393, Operation And Maintenance Manual

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TROUBLESHOOTING GUIDE 

This section provides a list of the more frequently encountered malfunctions, their cause and corrective 

actions. The operator or maintenance personnel can  perform some corrective actions, and others may 

require the assistance of a qualified Bostitch technician or your dealer.

DEFECTIVE PATTERN 

LIKELY CAUSE

SUGGESTED REMEDY

HEAVY TOP OR

BOTTOM PATTERN

1. Dirty or damaged  

    air cap

2. Dirty or damaged  

    fluid tip

1. Rotate air cap 180°. If the  

    pattern   follows the air cap,  

    the problem is in the air cap.  

    Clean and inspect the air cap.  

    If the pattern is not corrected, 

    replacement is necessary. 

2. If pattern doesn’t follow the 

    air cap, the problem is with 

    the fluid tip. Clean and 

    inspect the tip for dried paint, 

    dirt or damage. If the pattern 

    is not corrected, replacement  

    is necessary.

SPLIT PATTERN

Air pressure too high for 

material viscosity being sprayed.

1. Reduce air pressure.

2. Turn pattern control knob 

   clockwise to decrease fan  

   width. Turn fluid needle  

   adjusting nut counterclockwise  

   to increase fluid flow.

1. Dirty or distorted air horn  

    holes.

2. One of the air horn holes 

    completely obstructed.

1. Rotate air cap 180°. If the  

    pattern follows the air cap,  

    the problem is in the air cap.

2. Clean and inspect the horn  

    holes. If the horn holes are  

    distorted, replacement is 

    necessary. 

GUN SPLITTING  

Air getting into paint stream 

somewhere.

Example: Same symptoms as a 

cup running out paint. 

1. Check and tighten fluid needle  

    packing nut.

2. Tighten fluid tip.

3. Check fluid tip seat for  

    damage.

4. Check for poor gun to cup 

    seating.

5. Check that cup is correctly  

    fastened on the gun.

SPITTING, IRREQULAR

OR FLUTTERING SPRAY

1. Fluid nozzle  

    cracked or worn

2. Leak at thread  

   of fluid nozzle

3. Leak at fluid needle

4. Needle packing  

    worn out

5. Insufficient fluid in cup

6. Vent hole in  

    container cover clogged

1. Tighten or replace

2. Tighten fluid nozzle

3. Tighten compression nut 

   assembly or replace needle  

   packing

4. Replace packing

5. Fill cup with fluid

6. Clean out

AIR BACK 

PRESSURING 

INTO CUP.

Excessive air blowing back into 

cup.

1.  Tighten fluid tip.

2. Check fluid tip seat.

3. Check for damaged fluid seat  

    on tip or seat on gun head.