Graco LineLazer IV 3900

Other manuals for Graco LineLazer IV 3900

Repair And Parts38 pages

Repair Parts List38 pages

Important Safety Instructions36 pages

Questions and Answers

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Christina MeyerNov 23, 2025
What to do if Graco LineLazer IV 3900 Construction Equipment pump output is low?
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  Jeremy TateNov 23, 2025
  If the pump output on your Graco Construction Equipment is low, consider the following: * The strainer is clogged: Clean the strainer. * The piston ball is not seating: Service the piston ball. * The piston packings are worn or damaged: Replace the packings. * The O-ring in the pump is worn or damaged: Replace the O-ring. * The intake valve ball is not seating properly or is packed with material: Clean the intake valve. * The engine speed is too low: Increase the throttle setting. * The clutch is worn or damaged: Replace the clutch. * The pressure setting is too low: Increase the pressure. * The fluid filter, tip filter, or tip is clogged or dirty: Clean the filter. * There is a large pressure drop in the hose with heavy materials: Use a larger diameter hose and/or red...
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Monica WellsAug 27, 2025
What to do if fluid is spitting from my Graco LineLazer IV 3900 gun?
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  smithjesseAug 27, 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.
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Amber ValentineAug 27, 2025
What to do if I see excessive paint leakage into the throat packing nut of my Graco LineLazer IV 3900?
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  Courtney ElliottAug 27, 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.
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Erin PotterAug 28, 2025
What to do if my Graco Construction Equipment pump is difficult to prime?
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  Laura GarzaAug 28, 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.
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mirandamanningNov 24, 2025
What to do if my Graco LineLazer IV 3900 Construction Equipment engine operates, but displacement pump doesn't?
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  Kristen MorenoNov 24, 2025
  If your Graco Construction Equipment engine operates, but the displacement pump does not, check the following: * The pump switch is OFF: Turn the pump switch ON. * The pressure setting is too low: Turn the pressure adjusting knob clockwise to increase pressure. * The fluid filter is dirty: Clean the filter. * The tip or tip filter is clogged: Clean the tip or tip filter. * The displacement pump piston rod is stuck due to dried paint: Repair the pump. * The connecting rod is worn or damaged: Replace the connecting rod. * The drive housing is worn or damaged: Replace the drive housing. * Electrical power is not energizing the clutch field: Check wiring connections. With the pump switch ON and pressure turned to MAXIMUM, use a test light to check for power between clutch test...
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Ethan BellSep 15, 2025
What to do if the distance counter is not operating properly on my Graco Construction Equipment?
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  Bonnie ThomasSep 15, 2025
  If the distance counter on your Graco Construction Equipment is not operating properly, the trigger sensor might not be set correctly. Check the connector and reconnect if there are bad wiring connections. It could also be that the gear teeth are missing or damaged (replace the distance gear/wheel), or the wire is cracked or broken (replace the sensor).
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valerie87Sep 13, 2025
What to do if the gallon counter is not working on my Graco Construction Equipment?
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  Maria JonesSep 13, 2025
  If the gallon counter on your Graco Construction Equipment isn't working, check for broken or disconnected wires (check wires and connections, replace broken wires). It could also be due to a bad sensor (replace the sensor) or a missing magnet (reposition or replace the magnet).
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Brandon WilliamsSep 14, 2025
What to do if the sprayer operates, but the display does not on my Graco Construction Equipment?
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  Michelle MercadoSep 14, 2025
  If your Graco Construction Equipment sprayer operates but the display doesn't, it could be due to a bad connection between the control board and the display (remove the display and reconnect it). Alternatively, the display might be damaged (replace the display).
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evansjohnSep 5, 2025
How to fix spray icon not showing on Graco LineLazer IV 3900 display when fluid is sprayed?
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  Aaron SmithSep 6, 2025
  If the spray icon does not appear on the display when fluid is sprayed from your Graco Construction Equipment, check the following: * Loose connector: Check the connector and reconnect it. * Interrupter is improperly positioned: Turn the screw counterclockwise until the spray icon synchronizes with fluid spray. * Reed switch assembly is damaged: Replace the reed switch assembly. * Magnet on assembly is missing: Replace the reed switch assembly. * Cut or sliced wire: Replace the distance sensor harness. * Control board is damaged: Replace the control board. * Display is damaged: Replace the display.
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jamesheidiSep 3, 2025
What causes fluid spray to start after spray icon on Graco LineLazer IV 3900 display?
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  alicialoweSep 4, 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.