Graco GMAX II 7900

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 rope 3 or 4 times. Clean or replace spark plug. Try to start engine. Keep sprayer upright to avoid oil seepage.

From 308870 rev G, page 7

1. Pressure control switch is OFF Turn pressure control switch ON.
2. Pressure setting is too low Turn pressure adjusting knob clock- wise to increase pressure
3. Fluid filter (318) is dirty Clean filter. Page 31.
4. Tip or tip filter is clogged Clean tip or tip filter. Manual 309091.
5. Displacement pump piston rod is stuck due to dried paint Repair pump. Manual 308798.
6. Roller bearings are worn or dam- aged Replace connecting rod. Page 10.
7. Drive housing is worn or damaged Replace drive housing. Page 10.

From 308870 rev G, page 7

1. Electrical power is not energizing clutch field Check wiring connections. Page 15. Reference control board diagnos- tics. Page 21. With pressure control switch ON and pressure turned to MAXIMUM, use a test light to check for power between clutch terminals on control board. Remove black clutch wires from control board and measure resis- tance across wires. At 70_ F, the resistance must be between 1.7 +0.2W; if not, replace clutch coil 241121. Have pressure control checked by authorized Graco dealer.
2. Clutch is worn or damaged Replace clutch. Page 13.
3. Pinion assembly is worn or dam- aged Repair or replace pinion assembly. Page 13.

From 308870 rev G, page 8

1. Strainer (31) is clogged Clean strainer
2. Piston ball (25) is not seating Service piston ball. Manual 308798.
3. Piston packings are worn or dam- aged Replace packings. Manual 308798.
4. O-ring (227) in displacement pump is worn or damaged Replace o-ring. Manual 308798.
5. Intake valve ball is not seating prop- erly Clean intake valve. manual 308798.
6. Engine speed is too low Increase throttle setting. Manual 308867.
7. Clutch is worn or damaged Replace clutch. Page 13.
8. Pressure setting is too low Increase pressure. Manual 308867.
9. Fluid filter (318), tip filter or tip is clogged or dirty Clean filter. Manual 308867 or 309091.
10. 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 opti- mum performance (50 ft minimum).

From 308870 rev G, page 8

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 dam- aged Replace packings. Manual 308798.
3. Displacement rod is worn or dam- aged Replace rod. Manual 308798.

From 308870 rev G, page 9

1. Air in pump or hose Check and tighten all fluid connec- tions. Reprime pump. Manual 308867.
2. Tip is partially clogged Clear tip. Manual 309091.
3. Fluid supply is low or empty Refill fluid supply. Prime pump. Manual 308867. Check fluid supply often to prevent running pump dry.

From 308870 rev G, page 9

1. Air in pump or hose Check and tighten all fluid connec- tions. 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 308798.
4. Paint is too thick Thin the paint according to the sup- plier's recommendations.
5. Engine speed is too high Decrease throttle setting before priming pump. Manual 308867.

From 308870 rev G, page 9

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 308870 rev G, page 9

1. Engine speed is to slow - Increase throttle setting. - Adjust engine speed at no load to 3750 - 3850 rpm
2. Fluid filter is clogged Relieve pressure and clean filter
3. Too much pump friction (new pump) Reduce pressure to 3000 psi (20.68 MPa, 206.8 bar) until pump wears in
4. Spark plug wire is loose Reconnect wire

From 308870 rev G, page 9

1. Fault condition exists Determine fault correction from table, page 15

From 310893 rev P, page 6

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

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

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

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

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

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

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

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

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

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

1. Display damaged or has bad connection Check connections. Replace display.

From 310893 rev P, page 7

1. Fault condition exists. Determine fault correction from table, page 35.

From 3A6400 rev B, page 28

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

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

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

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

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

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

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

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

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

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

1. Display damaged or has bad connection. Check connections. Replace display.

From 3A6400 rev B, page 30

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

1. Fault condition exists. Determine fault correction from table, page 31.

From 332919 rev G, page 22

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

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

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

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

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

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

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

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

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

1. Display damaged or has bad connec- tion. Check connections. Replace display.

From 332919 rev G, page 23

1. Fault condition exists. Determine fault correction from table, page 14.

From 3A0243 rev B, page 5

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

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

1. Error code displayed. Reference Pressure Control repair, page 21.
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. Replace connecting rod. Page 15.
8. Drive housing is worn or damaged. Replace drive housing. Page 16.
9. 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.
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

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. Page 17.
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 3A0243 rev B, page 6

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

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

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

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

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

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

1. Display damaged or has bad connec- tion. Check connections. Replace display.

From 3A0243 rev B, page 6

1. Operating conditions out of WatchDog parameters Turn pressure down. Contact Graco Technical Assistance to adjust WatchDog parameters. Operate without WatchDog active; Manual 309408.
2. Low pump output. See Troubleshooting Table, Pump Outlet Low, page 6.

From 309412 rev D, page 5

1. Strainer (89) 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 displacement pump is worn or dam- aged 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. Manual 309890.
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 309412 rev D, page 6

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

From 309412 rev D, page 7