Graco LineLazer v 3900 User Manual (English)

Questions and Answers:

N
Nicholas ColemanAug 21, 2025
Why won't my Graco LineLazer v 3900 Paint Sprayer engine start?
- M
  Meagan ParkerAug 21, 2025
  Your Graco Paint Sprayer engine may not start due to several reasons: the engine switch might be OFF, so turn it ON. The engine could be out of gas, so refill the gas tank. The engine oil level might be low, so replenish oil if necessary. The spark plug cable might be disconnected or damaged, so connect or replace the spark plug. If it's a cold engine, use the choke. The fuel shutoff lever might be OFF, so move it to the ON position. Oil might be seeping into the combustion chamber, so remove the spark plug, pull the starter 3 to 4 times, clean or replace the spark plug, and start the engine, keeping the sprayer upright to avoid oil seepage.
S
Susan VelasquezAug 25, 2025
What to do if Graco Paint Sprayer is difficult to prime?
- A
  Amanda LopezAug 25, 2025
  If your Graco paint sprayer is difficult to prime, here are a few things to check. Make sure there's no air in the pump or hose by checking and tightening all fluid connections, and reduce engine speed to cycle the pump as slowly as possible during priming. Inspect the intake valve for leaks and clean it, ensuring the ball seat isn't nicked or worn and that the ball seats well before reassembling the valve. If the pump packings are worn, replace them. If the paint is too thick, thin it according to the supplier’s recommendations. Finally, ensure the engine speed isn't too high by decreasing the throttle setting before priming the pump.
W
Wayne HarmonAug 26, 2025
What to do if I see excessive paint leakage into the throat packing nut of my Graco LineLazer v 3900?
- K
  Kristen BarberAug 26, 2025
  If you notice excessive paint leakage into the throat packing nut of your Graco paint sprayer, it could be that the throat packing nut is loose, so remove the throat packing nut spacer and tighten the throat packing nut just enough to stop the leakage. Another reason could be that the throat packings are worn or damaged, so replace the packings. Finally, the displacement rod might be worn or damaged, so replace the rod.
B
Brandy HallAug 29, 2025
What to do if my Graco LineLazer v 3900 engine operates, but displacement pump does not?
- L
  Lauren SchwartzAug 29, 2025
  If the engine of your Graco paint sprayer operates, but the displacement pump does not, verify the pump switch is ON. Increase the pressure by turning the pressure adjusting knob clockwise. Clean the fluid filter if it is dirty. Clean the tip or tip filter if clogged. If the displacement pump piston rod is stuck due to dried paint, repair the pump. Replace the connecting rod if it is worn or damaged. Replace the drive housing if it is worn or damaged. Check the wiring connections if electrical power is not energizing the clutch field. Replace the clutch if it is worn, damaged, or incorrectly positioned. Repair or replace the pinion assembly if it is worn or damaged.
E
ewardAug 31, 2025
Why is the line spacing not accurate on my Graco Paint Sprayer?
- J
  Jacob HensleyAug 31, 2025
  If the line spacing is not accurate on your Graco Paint Sprayer, the wrong line pattern might be loaded, so reload the correct pattern. Alternatively, the machine might be out of calibration, so calibrate the machine.
C
cindy11Sep 1, 2025
What to do if my Graco LineLazer v 3900 battery won’t stay charged?
- J
  Jonathan ZhangSep 2, 2025
  If your Graco Paint Sprayer battery won’t stay charged, consider these potential causes: Accessories might be left on, draining the battery when the unit is not running, so turn off accessories when the machine is not in use. The throttle might not be set high enough, so ensure the engine is running above 3300 rpm NO LOAD for proper power supply. Power consumption from accessories might be higher than engine output, so reduce accessories or charge the battery when necessary. There might be broken or disconnected wiring, so check the wiring and repair or replace wires if necessary. The charger might not be working, so check the charging state in diagnostics to see if the charger is properly working and replace the board if needed.
L
lsmithSep 3, 2025
What to do if my Graco Paint Sprayer's auto gun won't shut off?
- C
  Carolyn AndersonSep 3, 2025
  If the auto gun on your Graco paint sprayer won't shut off, the cable might be kinked, so repair or replace the cable. The solenoid might be jammed, so lubricate the solenoid plunger and check for solenoid damage. A needle in the gun might be clogged, so clean out the gun.
T
Trevor WeberSep 5, 2025
Why is the gallon (liter) counter not adding fluid volume on my Graco LineLazer v 3900 Paint Sprayer?
- F
  Frank GarciaSep 5, 2025
  If the gallon (liter) counter is not adding fluid volume on your Graco paint sprayer, the fluid pressure might not be high enough, so ensure it is over 800 psi (55 bar) for the counter to add. There might be a broken or disconnected pump counter wire, so check the wires and connections and replace any broken wires. A magnet might be missing or damaged, so reposition or replace the magnet on the pump. The sensor might be bad, so replace the sensor.
M
michaeledwardsSep 6, 2025
Why is my Graco Paint Sprayer operating, but the display does not?
- M
  Mark DuncanSep 7, 2025
  If your Graco paint sprayer operates, but the display does not, it could be due to a bad connection between the control board and the display, so remove the display and reconnect it. Alternatively, the display might be damaged, so replace the display.
S
smithamandaSep 8, 2025
Why is the distance not adding properly on my Graco LineLazer v 3900 Paint Sprayer?
- J
  Joshua PriceSep 8, 2025
  If the distance is not adding properly on your Graco paint sprayer (measure mode will be inaccurate and speed will be wrong), the machine might not be calibrated, so perform the calibration procedure. The rear tire pressure might be too low or too high, so adjust the tire pressure to 55 +/- 5 psi (380 +/- 34kPa). Gear teeth might be missing or damaged (right side when standing on the platform), so replace the distance gear/wheel hub. The distance sensor might be loose or broken, so reconnect or replace the sensor.

Graco LineLazer v 3900 Specifications

General

Brand	Graco
Model	LineLazer v 3900
Category	Paint Sprayer
Language	English

Summary

Setup/Startup

SwitchTip and Guard Assembly

Procedure for installing the SwitchTip and guard onto the spray gun for proper operation.

Gun Placement

Gun Installation and Positioning

Instructions for inserting, positioning, and adjusting guns and gun arms.

Gun Configuration and Adjustment

Selecting and configuring standard or auto guns, including charts and HP Auto Series setup.

Trigger, Cable, and Laser Setup

Adjusting trigger sensors, gun cables, alignment, and dot laser installation.

LineLazer V LiveLook Display (Standard Series)

Initial Setup and Calibration

Guide to configuring language, units, and calibration for the standard series LiveLook display.

Operating Modes

Instructions for operating in Striping Mode and Measure Mode, including screen functions and spraying.

System Settings and Information

Navigating Setup/Information, Settings, and Information menus for system data and adjustments.

LineLazer V LiveLook Display (HP Auto Series)

Initial Setup and Calibration

Configuration steps for language, units, and calibration specific to the HP Auto Series display.

Operating Modes

Instructions for HP Auto Series operation in Striping Mode and Measure Mode, including gun actuation.

Layout and Marking Functions

Utilizing Layout Mode, Stall Calculator, Angle Calculator, and Marker Layout for precise area marking.

Maintenance

Caster Wheel Maintenance

Annual and monthly procedures for caster wheel tightening, greasing, and alignment.

Troubleshooting

Engine, Pump, and Fluid Issues

Diagnosing and resolving engine starting, low pump output, and fluid spitting problems.

Electrical and Control System Issues

Troubleshooting display errors, spray icon problems, auto gun functionality, and battery charging.

Layout Mode and Pump Operation Issues

Resolving issues with layout mode dots and a continuously running fluid pump.

Pinion Assembly/Clutch Armature/Clamp

Removal Procedures

Step-by-step instructions for removing pinion assembly, clutch armature, and associated components.

Installation Procedures

Guidelines for installing clutch armature, pinion assembly, and clamp with correct torque.

Graco LineLazer v 3900 User Manual

Table of Contents

Questions and Answers:

Graco LineLazer v 3900 Specifications

Summary

Setup/Startup

SwitchTip and Guard Assembly

Gun Placement

Gun Installation and Positioning

Gun Configuration and Adjustment

Trigger, Cable, and Laser Setup

LineLazer V LiveLook Display (Standard Series)

Initial Setup and Calibration

Operating Modes

System Settings and Information

LineLazer V LiveLook Display (HP Auto Series)

Initial Setup and Calibration

Operating Modes

Layout and Marking Functions

Maintenance

Caster Wheel Maintenance

Troubleshooting

Engine, Pump, and Fluid Issues

Electrical and Control System Issues

Layout Mode and Pump Operation Issues

Pinion Assembly/Clutch Armature/Clamp

Removal Procedures

Installation Procedures