Graco GMAX II 3900

Manuals, pump repair kits, parts and troubleshooting for the Graco GMAX II 3900, from Graco's own manuals and parts lists.

Find your version

Find the model number on your sprayer's data plate and match it to the first column. Each row shows the pump Graco's Parts Book lists for that model and the pump's repair kit.

Repair kits listed

Graco GMAX II 3900 versions
Model numberParts Book titleSeriesYearsPump and repair kit
17A624GMAX 3900 Express Standard Hi-Boy1/2019-/
  • Pump 17A138 Kit, Pump Repair (Standard)Repair kit 248212 $90.76
17E826GMAX II 3900 Standard Lo-Boy1/2019-/
  • Pump 16X414 ProContractor ProConnect II Pump Kit (Standard)Repair kit 248212 $90.76
17E827GMAX II 3900 Standard Hi-Boy1/2019-/
  • Pump 16Y598 $704.99 Standard Threaded Pump (Standard)Repair kit 248212 $90.76
17E828GMAX II 3900 ProContractor Hi-Boy1/2019-/
  • Pump 17H823 $1,268.40 ProConnect II MaxLife Vortex Pump (Standard)Repair kit 17H841 $106.60
17G998GMAX II 3900 Standard Lo-Boy CE1/2019-/
  • Pump 16X414 ProContractor ProConnect II Pump Kit (Standard)Repair kit 248212 $90.76
17G999GMAX II 3900 Standard Hi-Boy1/2019-/
  • Pump 16Y598 $704.99 Standard Threaded Pump (Standard)Repair kit 248212 $90.76
2326103900, GMax, (Non Display)5/1998-12/2001
  • Pump 239923 Displacement PumpRepair kit 248212 $90.76
2326113900, GMax, (Non Display)8/1998-1/2000
  • Pump 239923 Displacement PumpRepair kit 248212 $90.76
2326123900, GMax, (Non Display)5/1998-12/2001
  • Pump 239923 Displacement PumpRepair kit 248212 $90.76
2326133900, GMax, (Non Display)8/1998-1/2000
  • Pump 239923 Displacement PumpRepair kit 248212 $90.76
2337003900, GMax, LoBoy, Bare6/2001-4/2005
  • Pump 244197 Displacement PumpRepair kit 248212 $90.76
2337013900, GMax, HiBoy, Bare6/2001-4/2005
  • Pump 244197 Displacement PumpRepair kit 248212 $90.76
Show all 19 models
Graco GMAX II 3900 versions, continued
Model numberParts Book titleSeriesYearsPump and repair kit
2486833900, GMax II, Standard, Lo-BoyB1/2010-3/2014
  • Pump 287512 ProConnect Pump Kit (Standard)Repair kit 248212 $90.76
2486833900, GMax II, Standard, Lo-BoyA6/2004-1/2010
  • Pump 287512 ProConnect Pump Kit (Standard)Repair kit 248212 $90.76
2486843900, GMax II, Standard, Hi-BoyB1/2010-3/2014
  • Pump 287512 ProConnect Pump Kit (Standard)Repair kit 248212 $90.76
2486843900, GMax II, Standard, Hi-BoyA6/2004-1/2010
  • Pump 287512 ProConnect Pump Kit (Standard)Repair kit 248212 $90.76
2486853900, GMax II, Standard, Lo-Boy6/2004-1/2010
  • Pump 287512 ProConnect Pump Kit (Standard)Repair kit 248212 $90.76
2486863900, GMax II, Premium, Hi-Boy6/2004-1/2010
  • Pump 287512 ProConnect Pump Kit (Standard)Repair kit 248212 $90.76
2587313900, GMax II, Premium, Hi-Boy1/2010-3/2014
  • Pump 287512 ProConnect Pump Kit (Standard)Repair kit 248212 $90.76

Manuals

Links open the manufacturer's official copy.

Parts we sell for the Graco GMAX II 3900

Filters (11)
Gun (3)
  • 287032 KIT, FILTER,GUN,60 MESH
  • 287033 KIT, FILTER,GUN,100 MESH
  • 288488 KIT, REPAIR, GUN, CONTRACTOR
Hose (8)
Kit (9)
  • 17A030 KIT,REPAIR, CYL., STANDARD
  • 17D888 KIT, REPLACEMENT, POTENTIOMETER
  • 17H841 KIT, REPAIR, PKG, 3900 PRO, QP
  • 17Y297 KIT, REPAIR, CARTRIDGE, PC GUN
  • 17Y466 KIT, TRIGGER, CONTRACTOR PC
  • 240523 KIT, REPLMNT, HOUSING, BEARING
  • 244240 KIT, REPAIR, RETURN LINE, HI
  • 248215 KIT, REPAIR, INTAKE TUBE
  • 288732 KIT, REPAIR, DRAIN HOSE
Motor (4)
Packing (5)
Pump (2)
  • 16Y598 KIT,PUMP,3900,695/795,STD
  • 17H823 KIT, PUMP, 3900PCII, MAXLIFE
Tip (3)
  • 17Y042 CONTRACTOR PC GUN,RAC X,LTX,PKGD
  • 288420 CONTRACTOR GUN,RAC X(PKGD)
  • LTX517 RAC X LTX TIP,SPRAY,517
Valve (4)
  • 235014 KIT, REPLACEMENT, DRAIN VALVE
  • 245103 KIT REPAIR, DRAIN VALVE
  • 24B156 VALVE, PRIME, HD, THREAD PATCH
  • 257352 KIT, REPAIR, PRIME VALVE, HD
Other parts (7)

Troubleshooting from the manual

E=XX is displayed
  1. Fault condition exists Determine fault correction from table, page 14.

From 309409 rev F, page 6

Engine won't start
  1. Engine switch is OFF Turn engine switch ON
  2. Engine is out of gas Refill gas tank. Honda Engines Owner's Manual.
  3. Engine oil level is low Try to start engine. Replenish oil, if necessary. Honda Engines Owner's Manual.
  4. Spark plug cable is disconnected or damaged Connect spark plug cable or replace spark plug
  5. Cold engine Use choke
  6. Fuel shutoff lever is OFF Move lever to ON position
  7. Oil is seeping into combustion chamber Remove spark plug. Pull starter 3 to 4 times. Clean or replace spark plug. Start engine. Keep sprayer upright to avoid oil seepage.

From 309409 rev F, page 6

False tripping of WatchDog system. EMPTY is displayed. Pump does not run.
  1. Operating conditions out of WatchDog param- eters Low pump output; page 7. Turn pressure down. Contact Graco Technical Assistance to adjust WatchDog parameters. Operate without WatchDog active; Manual 309408.

From 309409 rev F, page 6

Engine operates, but dis- placement pump does not operate
  1. Error code displayed? Reference pressure control repair. Page 15.
  2. Pump switch is OFF Turn pump switch ON.
  3. Pressure setting is too low Turn pressure adjusting knob clockwise to increase pressure.
  4. Fluid filter (318) is dirty Clean filter. Page 24.
  5. Tip or tip filter is clogged Clean tip or tip filter. Manual 309091.
  6. Displacement pump piston rod is stuck due to dried paint Repair pump. Manual 309277.
  7. Connecting rod is worn or damaged Replace connecting rod. Page 8.
  8. Drive housing is worn or damaged Replace drive housing. Page 9.
  9. Electrical power is not energizing clutch field Check wiring connections. Page 13. Reference pressure control repair. Page 15. Reference wiring diagram. Page 25. With pump switch ON and pressure turned to MAXIMUM, use a test light to check for power between clutch test points on control board. Remove 7- -pin connector from control board and measure resistance across clutch coil. At 70 _ F, the resistance must be between 1.2  0.2  (GMax 3900); 1.7  0.2  (GMax 5900); if not, replace pinion housing. Have pressure control checked by authorized Graco dealer.
  10. Clutch is worn, damaged, or incorrectly positioned Replace clutch. Page 10.
  11. Pinion assembly is worn or damaged Repair or replace pinion assembly. Page 10.

From 309409 rev F, page 6

Pump output is low
  1. Strainer (31) is clogged Clean strainer. Sprayer 233716 strainer is for use in paint only.
  2. Piston ball (206) is not seating Service piston ball. Manual 309277.
  3. Piston packings are worn or damaged Replace packings. Manual 309277.
  4. O-ring (227) in pump is worn or damaged Replace o-ring. Manual 309277.
  5. Intake valve ball is not seating properly Clean intake valve. Manual 309277.
  6. Intake valve ball is packed with material Clean intake valve. Manual 309277. Do not leave 233716 sprayer under pressure for more than 5 minutes when spraying texture and not actively spraying.
  7. Engine speed is too low Increase throttle setting. Manual 309408.
  8. Clutch is worn or damaged Replace clutch. Page 10.
  9. Pressure setting is too low Increase pressure. Manual 309408.
  10. Fluid filter (318), tip filter or tip is clogged or dirty Clean filter. Manual 309408 or 309091.
  11. Large pressure drop in hose with heavy materials Use larger diameter hose and/or reduce overall length of hose. Use of more than 100 ft of 1/4 in. hose significantly reduces performance of sprayer. Use 3/8 in. hose for optimum perfor- mance (50 ft minimum).

From 309409 rev F, page 7

Excessive paint leakage into throat packing nut
  1. Throat packing nut is loose Remove throat packing nut spacer. Tighten throat packing nut just enough to stop leakage.
  2. Throat packings are worn or damaged Replace packings. Manual 309277.
  3. Displacement rod is worn or damaged Replace rod. Manual 309277.

From 309409 rev F, page 7

Fluid is spitting from gun
  1. Air in pump or hose Check and tighten all fluid connections. Reprime pump. Manual 309408.
  2. Tip is partially clogged Clear tip. Manual 309091.
  3. Fluid supply is low or empty Refill fluid supply. Prime pump. Manual 309408. Check fluid supply often to prevent running pump dry.

From 309409 rev F, page 7

Pump is difficult to prime
  1. Air in pump or hose Check and tighten all fluid connections. Reduce engine speed and cycle pump as slowly as possible during priming.
  2. Intake valve is leaking Clean intake valve. Be sure ball seat is not nicked or worn and that ball seats well. Reas- semble valve.
  3. Pump packings are worn Replace pump packings. Manual 309277.
  4. Paint is too thick Thin the paint according to the supplier's recommendations
  5. Engine speed is too high Decrease throttle setting before priming pump. Manual 309408.

From 309409 rev F, page 7

Clutch squeaks each time clutch engages
  1. Clutch surfaces are not matched to each other when new and may cause noise Clutch surfaces need to wear into each other. Noise will dissipate after a day of run time.

From 309409 rev F, page 7

High engine speed at no load load
  1. Misadjusted throttle setting Reset throttle to 3700 engine rpm at no load
  2. Worn engine governor Replace or service engine governor

From 309409 rev F, page 7

Gallon counter not working
  1. Bad sensor, broken or disconnected wire. Displaced or missing magnet. Check connections. Replace sensor or wire. Reposition or replace magnet.

From 309409 rev F, page 7

No display, sprayer operates
  1. Display damaged or has bad connection Check connections. Replace display.

From 309409 rev F, page 7

E=XX is displayed
  1. Fault condition exists Determine fault correction from table, page 15

From 310893 rev P, page 6

Engine will not start
  1. Engine switch is OFF Turn engine switch ON
  2. Engine is out of gasoline Refill gas tank. Honda Engines Owner's Man- ual.
  3. Engine oil level is low Try to start engine. Replenish oil, if necessary. Honda Engines Owner's Manual.
  4. Spark plug is disconnected or damaged Connect spark plug cable or replace spark plug
  5. Cold engine Use choke
  6. Fuel shutoff lever is OFF Move lever to ON position
  7. Oil is seeping into combustion chamber Remove spark plug. Pull starter 3 to 4 times. Clean or replace spark plug. Start engine. Keep sprayer upright to avoid oil seepage

From 310893 rev P, page 6

False tripping of WatchDog system. EMPTY is displayed. Pump does not run.
  1. Operating conditions out of WatchDog parameters Pump output is low, page 7. Turn pressure down. Contact Graco Technical Assistance to adjust WatchDog parameters. Operate without WatchDog active; Manual 310892.

From 310893 rev P, page 6

Engine operates, but displacement pump does not operate
  1. Error code displayed Reference Pressure Control repair, page 15
  2. Pump switch is OFF Turn pump switch ON
  3. Pressure setting too low Turn pressure adjusting knob clockwise to increase pressure.
  4. Fluid filter (56) is dirty Clean filter. Page 28.
  5. Tip or tip filter is clogged Clean tip or tip filter. Manual 309639.
  6. Displacement pump piston rod is stuck due to dried paint Repair pump. Manual 310894.
  7. Connecting rod is worn or damaged Replace connecting rod. Page 8.
  8. Drive housing is worn or damaged Replace drive housing. Page 9.
  9. Electrical power is not energizing clutch field Check wiring connections. Page 12. Reference Digital Display Messages . Page 15. Reference wiring diagram. Page 29. With pump switch ON and pressure turned to MAXI- MUM, use a test light to check for power between clutch test points on control board. Remove clutch wires from control board and measure resistance across clutch coil. At 70° F, the resistance must be between 1.2 +0.2 Ω ; if not, replace pinion housing. Have pressure control checked by authorized Graco dealer
  10. Clutch is worn, damaged, or incorrectly Adjust or replace clutch. Page 10.
  11. Pinion assembly is worn or damaged Repair or replace pinion assembly. Page10.

From 310893 rev P, page 6

Pump output is low
  1. Strainer (82) is clogged Clean strainer.
  2. Piston ball is not seating Service piston ball. Manual 310894.
  3. Piston packings are worn or damaged Replace packings. Manual 310894.
  4. O-ring in pump is worn or damaged Replace o-ring. Manual 310894.
  5. Intake valve ball is not seating properly Clean intake valve. Manual 310894.
  6. Intake valve ball is packed with material Clean intake valve. Manual 310894.
  7. Engine speed is too low Increase throttle setting. Manual 310892.
  8. Clutch is worn or damaged Adjust or replace clutch. Page 10.
  9. Pressure setting is too low Increase pressure. Manual 310892.
  10. Fluid filter (56), tip filter or tip is clogged or dirty Clean filter. Manual 310892 or 309639.
  11. Large pressure drop in hose with heavy materials Use larger diameter hose and/or reduce overall length of hose. Use of more than 100 ft of 1/4 in. hose significantly reduces performance of sprayer. Use 3/8 in. hose for optimum performance (50 ft minimum).

From 310893 rev P, page 7

Excessive paint leakage into throat packing nut
  1. Throat packing nut is loose Remove throat packing nut spacer. Tighten throat packing nut just enough to stop leak- age.
  2. Throat packings are worn or damaged Replace packings. Manual 310894.
  3. Displacement rod is worn or damaged Replace rod. Manual 310894.

From 310893 rev P, page 7

Fluid is spitting from gun
  1. Air in pump or hose Check and tighten all fluid connections. Rep- rime pump. Manual 310892.
  2. Tip is partially clogged Clear tip. Manual 309639.
  3. Fluid supply is low or empty Refill fluid supply. Prime pump. Manual 310892. Check fluid supply often to prevent running pump dry.

From 310893 rev P, page 7

Pump is difficult to prime
  1. Air in pump or hose Check and tighten all fluid connections. Reduce engine speed and cycle pump as slowly as possible during priming.
  2. Intake valve is leaking Clean intake valve. Be sure ball seat is not nicked or worn and that ball seats well. Reassemble valve.
  3. Pump packings are worn Replace pump packings. Manual 310894.
  4. Paint is too thick Thin the paint according to the supplier's recommendations
  5. Engine speed is too high Decrease throttle setting before priming pump. Manual 310892.

From 310893 rev P, page 7

Clutch squeaks each time clutch engages
  1. Clutch surfaces are not matched to each other when new and may cause noise Clutch surfaces need to wear into each other. Noise will dissipate after a day of run time.

From 310893 rev P, page 7

High engine speed at no load
  1. Misadjusted throttle setting Reset throttle to 3300 engine rpm at no load.
  2. Worn engine governor Replace or service engine governor

From 310893 rev P, page 7

Gallon counter not working
  1. Bad sensor, broken or disconnected wire. Displaced or missing magnet. Check connections. Replace sensor or wire. Reposition or replace magnet.

From 310893 rev P, page 7

No display, sprayer operates
  1. Display damaged or has bad connection Check connections. Replace display.

From 310893 rev P, page 7

Engine will not start
  1. Engine switch is OFF. Turn engine switch ON.
  2. Engine is out of gasoline. Refill gas tank. Honda Engine Manual.
  3. Engine oil level is low. Try to start engine. Replenish oil, if necessary. Honda Engine Manual.
  4. Spark plug disconnected or damaged. Connect spark plug cable or replace spark plug.
  5. Engine is cold. Use choke.
  6. Fuel shutoff lever is OFF. Move lever to ON position.
  7. Oil is seeping into combustion cham- ber. Remove spark plug. Pull starter 3 to 4 times. Clean or replace spark plug. Start engine. Keep sprayer upright to avoid oil seepage.

From 334121 rev B, page 14

Engine operates, but displacement pump does not operate
  1. Pump switch is OFF. Turn pump switch ON.
  2. Pressure setting too low. Turn pressure adjusting knob clockwise to increase pressure.
  3. Fluid filter is dirty. Clean filter.
  4. Tip or tip filter is clogged. Clean tip or tip filter (see gun manual).
  5. Displacement pump piston rod is stuck due to dried paint. Repair pump (see pump manual).
  6. Connecting rod is worn or damaged. See Parts manual.
  7. Drive housing is worn or damaged. See Parts manual.
  8. Electrical power is not energizing clutch field. See Parts manual. With pump switch ON and pressure turned to MAXIMUM, use a test light to check for power between clutch test points on control board. Remove clutch wires from control board and measure resistance across clutch coil. At 70° F, the resistance must be between 1.2 + 0.2  , if not, replace pinion housing. Have pressure control checked by authorized Graco dealer.
  9. Clutch is worn, damaged, or incorrectly positioned. Adjust or replace clutch. See Pinion Assem- bly/Clutch Armature/Clamp , page 20.
  10. Pinion assembly is worn or damaged. Repair or replace pinion assembly. See Pinion Assembly/Clutch Armature/Clamp , page 20.

From 334121 rev B, page 14

Pump output is low
  1. Strainer is clogged. Clean strainer.
  2. Piston ball is not seating. Service piston ball (see pump manual).
  3. Piston packings are worn or damaged. Replace packings (see pump manual).
  4. O-ring in pump is worn or damaged. Replace o-ring (see pump manual).
  5. Intake valve ball is not seating properly. Clean intake valve (see pump manual).
  6. Intake valve ball is packed with mate- rial. Clean intake valve (see pump manual).
  7. Engine speed is too low. Increase throttle setting (see operation man- ual).
  8. Clutch is worn or damaged. Adjust or replace clutch. See Pinion Assem- bly/Clutch Armature/Clamp , page 20.
  9. Pressure setting is too low. Increase pressure (see operation manual).
  10. Fluid filter, tip filter or tip is clogged or dirty. Clean filter (see gun manual).
  11. Large pressure drop in hose with heavy materials. Use larger diameter hose and/or reduce overall length of hose. Use of more than 100 ft of 1/4 in. hose significantly reduces performance of sprayer. Use 3/8 in. hose for optimum perfor- mance (50 ft minimum).

From 334121 rev B, page 15

Excessive paint leakage into throat packing nut
  1. Throat packing nut is loose. Remove throat packing nut spacer. Tighten throat packing nut just enough to stop leakage.
  2. Throat packings are worn or damaged. Replace packings (see pump manual).
  3. Displacement rod is worn or damaged. Replace rod (see pump manual).

From 334121 rev B, page 15

Fluid is spitting from gun
  1. Air in pump or hose. Check and tighten all fluid connections. Rep- rime pump (see operation manual).
  2. Tip is partially clogged. Clear tip (see gun manual).
  3. Fluid supply is low or empty. Refill fluid supply. Prime pump (see operation manual). Check fluid supply often to prevent running pump dry.

From 334121 rev B, page 15

Pump is difficult to prime
  1. Air in pump or hose. Check and tighten all fluid connections. Reduce engine speed and cycle pump as slowly as possible during priming.
  2. Intake valve is leaking. Clean intake valve. Be sure ball seat is not nicked or worn and that ball seats well. Reas- semble valve.
  3. Pump packings are worn. Replace pump packings (see pump manual).
  4. Paint is too thick. Thin the paint according to the supplier's rec- ommendations.
  5. Engine speed is too high. Decrease throttle setting before priming pump (see operation manual).

From 334121 rev B, page 15

Clutch squeaks each time clutch engages
  1. Clutch surfaces are not matched to each other when new and may cause noise. Clutch surfaces need to wear into each other. Noise will dissipate after a day of run time.

From 334121 rev B, page 15

High engine speed at no load
  1. Misadjusted throttle setting. Reset throttle to 3300 engine rpm at no load.
  2. Worn engine governor. Replace or service engine governor.

From 334121 rev B, page 15

Gallon counter not working
  1. Bad sensor, broken or disconnected wire. Displaced or missing magnet. Check connections. Replace sensor or wire. Reposition or replace magnet.

From 334121 rev B, page 15

No display, sprayer operates
  1. Display damaged or has bad connec- tion. Check connections. Replace display.

From 334121 rev B, page 15

E=XX is displayed
  1. Fault condition exists. Determine fault correction from table, page 35.

From 3A6400 rev B, page 28

Engine will not start
  1. Engine switch is OFF. Turn engine switch ON.
  2. Engine is out of gasoline. Refill gas tank. Honda Engine Manual.
  3. Engine oil level is low. Try to start engine. Replenish oil, if necessary. Honda Engine Manual.
  4. Spark plug disconnected or damaged. Connect spark plug cable or replace spark plug.
  5. Engine is cold. Use choke.
  6. Fuel shutoff lever is OFF. Move lever to ON position.
  7. Oil is seeping into combustion chamber. Remove spark plug. Pull starter 3 to 4 times. Clean or replace spark plug. Start engine. Keep sprayer upright to avoid oil seepage.

From 3A6400 rev B, page 28

False tripping of WatchDog system. EMPTY is displayed. Pump does not run.
  1. Operating conditions out of WatchDog parameters. Pump output is low, page 29. Turn pressure down. Contact Graco Technical Assistance to adjust WatchDog parameters. Operate without WatchDog active (see Operation manual).

From 3A6400 rev B, page 28

Engine operates, but displacement pump does not operate
  1. Error code displayed. See LED Display Messages , page 38.
  2. Pump switch is OFF. Turn pump switch ON.
  3. Pressure setting too low. Turn pressure adjusting knob clockwise to increase pressure.
  4. Fluid filter is dirty. Clean filter.
  5. Tip or tip filter is clogged. Clean tip or tip filter (see gun manual).
  6. Displacement pump piston rod is stuck due to dried paint. Repair pump (see pump manual).
  7. Connecting rod is worn or damaged. See Parts manual.
  8. Drive housing is worn or damaged. See Parts manual.
  9. Electrical power is not energizing clutch field. See Parts manual. See LED Display Messages , page 38. With pump switch ON and pressure turned to MAXIMUM, use a test light to check for power between clutch test points on control board. Remove clutch wires from control board and measure resistance across clutch coil. At 70° F, the resistance must be between for 3900 - 1.2 + 0.2  , for 5900/7900 1.7 ± 0.2  ; if not, replace pinion housing. Have pressure control checked by authorized Graco dealer.
  10. Clutch is worn, damaged, or incorrectly positioned. Adjust or replace clutch. See page 39.
  11. Pinion assembly is worn or damaged. Repair or replace pinion assembly. Page 39.

From 3A6400 rev B, page 29

Pump output is low
  1. Strainer is clogged. Clean strainer.
  2. Piston ball is not seating. Service piston ball (see pump manual).
  3. Piston packings are worn or damaged. Replace packings (see pump manual).
  4. O-ring in pump is worn or damaged. Replace o-ring (see pump manual).
  5. Intake valve ball is not seating properly. Clean intake valve (see pump manual).
  6. Intake valve ball is packed with material. Clean intake valve (see pump manual).
  7. Engine speed is too low. Increase throttle setting (see operation manual).
  8. Clutch is worn or damaged. Adjust or replace clutch. Page 39.
  9. Pressure setting is too low. Increase pressure (see operation manual).
  10. Fluid filter, tip filter or tip is clogged or dirty. Clean filter (see gun manual).
  11. Large pressure drop in hose with heavy materials. Use larger diameter hose and/or reduce overall length of hose. Use of more than 100 ft of 1/4 in. hose significantly reduces performance of sprayer. Use 3/8 in. hose for optimum performance (50 ft minimum).

From 3A6400 rev B, page 29

Excessive paint leakage into throat packing nut
  1. Throat packing nut is loose. Remove throat packing nut spacer. Tighten throat packing nut just enough to stop leakage.
  2. Throat packings are worn or damaged. Replace packings (see pump manual).
  3. Displacement rod is worn or damaged. Replace rod (see pump manual).

From 3A6400 rev B, page 30

Fluid is spitting from gun
  1. Air in pump or hose. Check and tighten all fluid connections. Reprime pump (see operation manual).
  2. Tip is partially clogged. Clear tip (see gun manual).
  3. Fluid supply is low or empty. Refill fluid supply. Prime pump (see operation manual). Check fluid supply often to prevent running pump dry.

From 3A6400 rev B, page 30

Pump is difficult to prime
  1. Air in pump or hose. Check and tighten intake tube connections. Reduce engine speed and cycle pump as slowly as possible during priming.
  2. Intake valve is leaking. Clean intake valve. Be sure ball seat is not nicked or worn and that ball seats well. Reassemble valve.
  3. Pump packings are worn. Replace pump packings (see pump manual).
  4. Engine speed is too high. Decrease throttle setting before priming pump (see operation manual).

From 3A6400 rev B, page 30

Clutch squeaks each time clutch engages
  1. Clutch surfaces are not matched to each other when new and may cause noise. Clutch surfaces need to wear into each other. Noise will dissipate after a day of run time.

From 3A6400 rev B, page 30

High engine speed at no load
  1. Misadjusted throttle setting. Reset throttle to 3300 engine rpm at no load.
  2. Worn engine governor. Replace or service engine governor.

From 3A6400 rev B, page 30

Gallon counter not working
  1. Bad sensor, broken or disconnected wire. Displaced or missing magnet. Check connections. Replace sensor or wire. Reposition or replace magnet.

From 3A6400 rev B, page 30

No display, sprayer operates
  1. Display damaged or has bad connection. Check connections. Replace display.

From 3A6400 rev B, page 30

Engine operates, but displacement pump does not operate
  1. Electrical power is not energizing clutch field. Check wiring connections. Page 21. Reference Digital Display Messages . Page 14. Reference wiring diagram. Page 21. With pump switch ON and pressure turned to MAXIMUM, use a test light to check for power between clutch test points on control board. Remove clutch wires from control board and measure resistance across clutch coil. At 70° F, the resistance must be between 1.2 + 0.2 Ω ; if not, replace pinion housing. Have pressure control checked by authorized Graco dealer.
  2. Error code displayed. Reference Pressure Control repair, page 21.
  3. Pump switch is OFF. Turn pump switch ON.
  4. Pressure setting too low. Turn pressure adjusting knob clockwise to increase pressure.
  5. Fluid filter is dirty. Clean filter.
  6. Tip or tip filter is clogged. Clean tip or tip filter (see gun manual).
  7. Displacement pump piston rod is stuck due to dried paint. Repair pump (see pump manual).
  8. Connecting rod is worn or damaged. Replace connecting rod. Page 15.
  9. Drive housing is worn or damaged. Replace drive housing. Page 16.
  10. Clutch is worn, damaged, or incorrectly positioned. Adjust or replace clutch. Page 19.
  11. Pinion assembly is worn or damaged. Repair or replace pinion assembly. Page 17.

From 3A0243 rev B, page 5

Pump output is low
  1. Pressure setting is too low. Increase pressure (see operation manual).
  2. Strainer is clogged. Clean strainer.
  3. Piston ball is not seating. Service piston ball (see pump manual).
  4. Piston packings are worn or damaged. Replace packings (see pump manual).
  5. O-ring in pump is worn or damaged. Replace o-ring (see pump manual).
  6. Intake valve ball is not seating properly. Clean intake valve (see pump manual).
  7. Intake valve ball is packed with mate- rial. Clean intake valve (see pump manual).
  8. Engine speed is too low. Increase throttle setting (see operation man- ual).
  9. Clutch is worn or damaged. Adjust or replace clutch. Page 17.
  10. Fluid filter, tip filter or tip is clogged or dirty. Clean filter (see gun manual).
  11. Large pressure drop in hose with heavy materials. Use larger diameter hose and/or reduce overall length of hose. Use of more than 100 ft of 1/4 in. hose significantly reduces performance of sprayer. Use 3/8 in. hose for optimum perfor- mance (50 ft minimum).

From 3A0243 rev B, page 6

Engine operates, but displacement pump does not operate
  1. Displacement pump piston rod is stuck due to dried paint. Repair pump (see pump manual).
  2. Connecting rod is worn or damaged. See Parts manual.
  3. Drive housing is worn or damaged. See Parts manual.
  4. Electrical power is not energizing clutch field. See Parts manual. See Digital Display Messages , page 31. With pump switch ON and pressure turned to MAXIMUM, use a test light to check for power between clutch test points on control board. Remove clutch wires from control board and measure resistance across clutch coil. At 70° F, the resistance must be between for 3900 - 1.2 + 0.2 Ω , for 5900/7900 1.7 ± 0.2 Ω ; if not, replace pinion housing. Have pressure control checked by authorized Graco dealer. 32.
  5. Clutch is worn, damaged, or incorrectly positioned. Adjust or replace clutch. See page
  6. Pinion assembly is worn or damaged. Repair or replace pinion assembly. Page 32.
  7. Tip or tip filter is clogged. Clean tip or tip filter (see gun manual).
  8. Error code displayed. See Digital Display Messages , page 31.
  9. Pump switch is OFF. Turn pump switch ON.
  10. Pressure setting too low. Turn pressure adjusting knob clockwise to increase pressure.
  11. Fluid filter is dirty. Clean filter.

From 332919 rev G, page 22

E=XX is displayed
  1. Fault condition exists. Determine fault correction from table, page 31.

From 332919 rev G, page 22

Pump output is low
  1. O-ring in pump is worn or damaged. Replace o-ring (see pump manual).
  2. Strainer is clogged. Clean strainer.
  3. Piston ball is not seating. Service piston ball (see pump manual).
  4. Piston packings are worn or damaged. Replace packings (see pump manual).
  5. Intake valve ball is not seating properly. Clean intake valve (see pump manual).
  6. Intake valve ball is packed with mate- rial. Clean intake valve (see pump manual).
  7. Engine speed is too low. Increase throttle setting (see operation man- ual).
  8. Clutch is worn or damaged. Adjust or replace clutch. Page 32.
  9. Pressure setting is too low. Increase pressure (see operation manual).
  10. Fluid filter, tip filter or tip is clogged or dirty. Clean filter (see gun manual).
  11. Large pressure drop in hose with heavy materials. Use larger diameter hose and/or reduce overall length of hose. Use of more than 100 ft of 1/4 in. hose significantly reduces performance of sprayer. Use 3/8 in. hose for optimum perfor- mance (50 ft minimum).

From 332919 rev G, page 23

Clutch squeaks each time clutch engages
  1. Clutch surfaces are not matched to each other when new and may cause noise. Clutch surfaces need to wear into each other. Noise will dissipate after a day of run time.

From 332919 rev G, page 23

Engine will not start
  1. Oil is seeping into combustion cham- ber. Remove spark plug. Pull starter 3 to 4 times. Clean or replace spark plug. Start engine. Keep sprayer upright to avoid oil seepage.
  2. Engine switch is OFF. Turn engine switch ON.
  3. Engine is out of gasoline. Refill gas tank. Honda Engine Manual.
  4. Engine oil level is low. Try to start engine. Replenish oil, if necessary. Honda Engine Manual.
  5. Spark plug disconnected or damaged. Connect spark plug cable or replace spark plug.
  6. Engine is cold. Use choke.
  7. Fuel shutoff lever is OFF. Move lever to ON position.

From 332919 rev G, page 22

False tripping of WatchDog system. EMPTY is displayed. Pump does not run.
  1. Operating conditions out of WatchDog parameters. Pump output is low, page 23. Turn pressure down. Contact Graco Technical Assistance to adjust WatchDog parameters. Operate without WatchDog active (see Opera- tion manual).

From 332919 rev G, page 22

Excessive paint leakage into throat packing nut
  1. Throat packing nut is loose. Remove throat packing nut spacer. Tighten throat packing nut just enough to stop leakage.
  2. Throat packings are worn or damaged. Replace packings (see pump manual).
  3. Displacement rod is worn or damaged. Replace rod (see pump manual).

From 332919 rev G, page 23

Fluid is spitting from gun
  1. Air in pump or hose. Check and tighten all fluid connections. Rep- rime pump (see operation manual).
  2. Tip is partially clogged. Clear tip (see gun manual).
  3. Fluid supply is low or empty. Refill fluid supply. Prime pump (see operation manual). Check fluid supply often to prevent running pump dry.

From 332919 rev G, page 23

Pump is difficult to prime
  1. Air in pump or hose. Check and tighten all fluid connections.
  2. Intake valve is leaking. Clean intake valve. Be sure ball seat is not nicked or worn and that ball seats well. Reas- semble valve.
  3. Pump packings are worn. Replace pump packings (see pump manual).
  4. Paint is too thick. Thin the paint according to the supplier's rec- ommendations.
  5. Engine speed is too high. Decrease throttle setting before priming pump (see operation manual).

From 332919 rev G, page 23

High engine speed at no load
  1. Misadjusted throttle setting. Reset throttle to 3300 engine rpm at no load.
  2. Worn engine governor. Replace or service engine governor.

From 332919 rev G, page 23

Gallon counter not working
  1. Bad sensor, broken or disconnected wire. Displaced or missing magnet. Check connections. Replace sensor or wire. Reposition or replace magnet.

From 332919 rev G, page 23

No display, sprayer operates
  1. Display damaged or has bad connec- tion. Check connections. Replace display.

From 332919 rev G, page 23

E=XX is displayed
  1. Fault condition exists. Determine fault correction from table, page 14.

From 3A0243 rev B, page 5

Engine will not start
  1. Engine switch is OFF. Turn engine switch ON.
  2. Engine is out of gasoline. Refill gas tank. Honda Engine Manual.
  3. Engine oil level is low. Try to start engine. Replenish oil, if necessary. Honda Engine Manual.
  4. Spark plug disconnected or damaged. Connect spark plug cable or replace spark plug.
  5. Engine is cold. Use choke.
  6. Fuel shutoff lever is OFF. Move lever to ON position.
  7. Oil is seeping into combustion chamber. Remove spark plug. Pull starter 3 to 4 times. Clean or replace spark plug. Start engine. Keep sprayer upright to avoid oil seepage.

From 3A0243 rev B, page 5

False tripping of WatchDog system. EMPTY is displayed. Pump does not run.
  1. Operating conditions out of WatchDog parameters. Pump output is low, page 6. Turn pressure down. Contact Graco Technical Assistance to adjust WatchDog parameters. Operate without WatchDog active (see Opera- tion manual).

From 3A0243 rev B, page 5

Excessive paint leakage into throat packing nut
  1. Throat packing nut is loose. Remove throat packing nut spacer. Tighten throat packing nut just enough to stop leakage.
  2. Throat packings are worn or damaged. Replace packings (see pump manual).
  3. Displacement rod is worn or damaged. Replace rod (see pump manual).

From 3A0243 rev B, page 6

Fluid is spitting from gun
  1. Air in pump or hose. Check and tighten all fluid connections. Rep- rime pump (see operation manual).
  2. Tip is partially clogged. Clear tip (see gun manual).
  3. Fluid supply is low or empty. Refill fluid supply. Prime pump (see operation manual). Check fluid supply often to prevent running pump dry.

From 3A0243 rev B, page 6

Pump is difficult to prime
  1. Air in pump or hose. Check and tighten all fluid connections.
  2. Intake valve is leaking. Clean intake valve. Be sure ball seat is not nicked or worn and that ball seats well. Reas-
  3. Pump packings are worn. Replace pump packings (see pump manual).
  4. Paint is too thick. Thin the paint according to the supplier's rec- ommendations.

From 3A0243 rev B, page 6

Clutch squeaks each time clutch engages
  1. Clutch surfaces are not matched to each other when new and may cause noise. Clutch surfaces need to wear into each other. Noise will dissipate after a day of run time.

From 3A0243 rev B, page 6

High engine speed at no load
  1. Misadjusted throttle setting. Reset throttle to 3300 engine rpm at no load.
  2. Worn engine governor. Replace or service engine governor.

From 3A0243 rev B, page 6

Gallon counter not working
  1. Bad sensor, broken or disconnected wire. Displaced or missing magnet. Check connections. Replace sensor or wire. Reposition or replace magnet.

From 3A0243 rev B, page 6

No display, sprayer operates
  1. Display damaged or has bad connec- tion. Check connections. Replace display.

From 3A0243 rev B, page 6

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