Replace reed switch assembly A connector on wiring harness or on reed switch (18) is damaged. Replace reed switch assembly Magnet on assembly is missing. Turn screw counter-clockwise until spray icon synchronizes with fluid spray. Check that 5-pin connector and reed switch are properly connected Interrupter is improperly positioned. Turn screw clockwise until spray icon is synchronized with fluid spray Spray icon does not show on display when fluid is sprayed. Interrupter (164) is improperly positioned. Turn screw counter-clockwise until spray icon synchronizes with fluid spray Fluid spray starts before spray icon is shown on display. Fluid spray starts after spray icon is shown on display. See "Spray icon does not show on display when fluid is sprayed". See "Distance counter not operating properly". Remove tire, and press in or pull out gear to align sensor and gear. Check connector, and reconnect Distance sensor not spaced correctly from gear. Excessive leakage around hydraulic motor piston rod wiper. Tighten throat packing nut just enough to stop leakage. Throat packing nut is loose Remove throat packing nut spacer. Excessive paint leakage into throat packing nut. Pump break-in period takes up to 100 gallons of material. Low stall or run pressure shown on display. Reset throttle to 3600–3800 engine rpm at no load. Noise will dissipate after a day of run time. Small irregularities of new clutch surfaces grind together and cause noise Clutch surfaces need to wear into each other. Decrease throttle setting before priming pump. Thin the paint according to the supplier's recommendations. Replace pump packings Paint is too thick. Be sure ball seat is not nicked or worn and that ball seats well. Reduce engine speed and cycle pump as slowly as possible during priming. Check fluid supply often to prevent running pump dry. hose for optimum performance Fluid is spitting from gun. hose significantly reduces performance of sprayer. Use larger diameter hose and/or reduce overall length of hose. Large pressure drop in hose with heavy materials. Fluid filter, tip filter or tip is clogged or dirty. Tighten wetcup just enough to stop leakage. Intake valve ball is not seating properly. Pump output is low on down stroke or on both strokes Hose strainer is clogged. O-ring in displacement pump is worn or damaged. Pump output is low on upstroke Hose inlet screen is clogged. Repair or replace pinion assembly, see pg. Clutch is worn, damaged, or incorrectly positioned. Have pressure control checked by and authorized Graco dealer. At 70° F, the resistance must be between 1.2 0.2Ω (LL 3900) 1.7 0.2Ω (LL 5900) if not, replace pinion housing.
Remove black clutch wires from control board and measure resistance across wires. With pressure control switch ON and pressure turned to MAXIMUM, use a test light to check for power between clutch terminals on control board. Electrical power is not energizing field.
Displacement pump piston rod is stuck due to dried paint. Turn pressure adjusting knob clockwise to increase pressure. Engine operates, but displacement pump does not operate. Keep sprayer upright to avoid oil seepage. Oil is seeping into combustion chamber Remove spark plug. Fuel shutoff lever is OFF Move lever to ON position 7. Spark plug cable is disconnected or damaged Connect spark plug cable or replace spark plug 5. Engine oil level is low Try to start engine. Engine switch is OFF Turn engine switch ON 2.
Problem Cause Solution Engine won't start 1.