Graco LineLazer IV 3900 Series

Questions and Answers

G
gentrymarcoAug 19, 2025
Why won't my Graco LineLazer IV 3900 engine start?
- L
  Latoya FranklinAug 20, 2025
  Your Graco Construction Equipment engine might not start due to several reasons: * The engine switch is OFF: Turn the engine switch ON. * The engine is out of gas: Refill the gas tank. * The engine oil level is low: Replenish the oil, if necessary. * The spark plug cable is disconnected or damaged: Connect the spark plug cable or replace the spark plug. * The engine is cold: Use the choke. * The fuel shutoff lever is OFF: Move the lever to the ON position. * Oil is seeping into the combustion chamber: Remove the spark plug, pull the starter 3 to 4 times, clean or replace the spark plug, and start the engine. Keep the sprayer upright to avoid oil seepage.
M
Mrs. Elizabeth Knapp MDAug 26, 2025
What to do if fluid is spitting from my Graco LineLazer IV 3900 gun?
- A
  Alexis ThompsonAug 26, 2025
  If fluid is spitting from the gun of your Graco Construction Equipment, here are a few things to check: * There's air in the pump or hose: Check and tighten all fluid connections, then reprime the pump. * The tip is partially clogged: Clear the tip. * The fluid supply is low or empty: Refill the fluid supply and prime the pump. Make sure to check the fluid supply often to prevent the pump from running dry.
B
bergeramandaAug 28, 2025
What to do if I see excessive paint leakage into the throat packing nut of my Graco Construction Equipment?
- D
  Daniel Hughes MDAug 28, 2025
  If you notice excessive paint leakage into the throat packing nut of your Graco Construction Equipment, try these solutions: * The throat packing nut is loose: Remove the throat packing nut spacer and tighten the throat packing nut just enough to stop the leakage. * The throat packings are worn or damaged: Replace the packings. * The displacement rod is worn or damaged: Replace the rod.
A
Alexandra WardAug 29, 2025
What to do if my Graco LineLazer IV 3900 pump is difficult to prime?
- E
  Emily WilsonAug 29, 2025
  If you're having trouble priming the pump on your Graco Construction Equipment, consider the following: * There's air in the pump or hose: Check and tighten all fluid connections. Reduce engine speed and cycle the pump as slowly as possible during priming. * The intake valve is leaking: Clean the intake valve, ensuring the ball seat is not nicked or worn and that the ball seats well. Reassemble the valve. * The pump packings are worn: Replace the pump packings. * The paint is too thick: Thin the paint according to the supplier’s recommendations. * The engine speed is too high: Decrease the throttle setting before priming the pump.
D
dalton51Sep 1, 2025
Why does my Graco LineLazer IV 3900 Construction Equipment clutch squeak each time it engages?
- T
  Tyler GomezSep 1, 2025
  The clutch on your Graco Construction Equipment may squeak when it engages because the clutch surfaces are new and not yet matched to each other. This noise should dissipate after a day of run time as the surfaces wear into each other.
Z
Zachary RobertsSep 2, 2025
What causes high engine speed at no load in Graco LineLazer IV 3900 Construction Equipment?
- R
  Rachel FitzpatrickSep 2, 2025
  High engine speed at no load in your Graco Construction Equipment can be caused by: * A misadjusted throttle setting: Reset the throttle to 3600 engine rpm at no load. * A worn engine governor: Replace or service the engine governor.
C
Carmen GarrettSep 4, 2025
How to fix Graco LineLazer IV 3900 Construction Equipment gallon counter not working?
- S
  Scott SextonSep 4, 2025
  If the gallon counter on your Graco Construction Equipment isn't working, check the following: * Broken or disconnected wire: Check the wires and connections, and replace any broken wires. * Bad sensor: Replace the sensor. * Missing magnet: Reposition or replace the magnet.
J
jenniferwhiteSep 7, 2025
What to do if my Graco Construction Equipment sprayer operates, but the display does not?
- B
  Brittney FordSep 7, 2025
  If your Graco Construction Equipment sprayer is operating but the display is not, try these steps: * Check for a bad connection between the control board and the display: Remove the display and reconnect it. * The display might be damaged: Replace the display.
P
Patrick DavidsonSep 8, 2025
How to troubleshoot Graco LineLazer IV 3900 Construction Equipment distance counter not operating properly?
- J
  Joseph SingletonSep 9, 2025
  If the distance counter on your Graco Construction Equipment is not operating properly, consider these potential issues: * The trigger sensor is not set correctly. * There are bad wiring connections: Check the connector and reconnect it. * The distance sensor is not spaced correctly from the gear: Adjust the space between the sensor and gear to .050 --/+ .020 in. * The distance sensor and gear are not aligned: Remove the tire, and press in or pull out the gear to align the sensor and gear. * Gear teeth are missing or damaged: Replace the distance gear/wheel. * The wire is cracked or broken: Replace the sensor.
G
grantjamesSep 12, 2025
What causes fluid spray to start after spray icon on Graco LineLazer IV 3900 Construction Equipment display?
- J
  Janice Perkins DDSSep 12, 2025
  If the fluid spray starts after the spray icon is shown on the display of your Graco Construction Equipment, it's likely that the interrupter is improperly positioned. Turn the screw counterclockwise until the spray icon synchronizes with the fluid spray.