Troubleshooting; Mechanical/Fluid Flow - Graco NOVA 390 PC Operation, Parts

Troubleshooting

Mechanical/Fluid Flow

1. Follow Pressure Relief Procedure,
page 12, before checking or repairing.
Problem
Pump output is low
334567E
2.
What to Check
If check is OK, go to next
check
Spray tip worn.
Spray tip clogged.
Paint supply.
Intake strainer clogged.
Intake valve ball and piston ball are
not seating properly.
Fluid filter or tip filter is clogged or
dirty.
Prime valve leaking.
Verify pump does not continue to
stroke when gun trigger is released.
(Prime valve not leaking.)
Leaking around throat packing nut
which may indicate worn or damaged
packings.
Troubleshooting
Check all possible problems and causes
before disassembling the unit.
When check is not OK,
refer to this column
Follow Pressure Relief Procedure,
page 12, then replace tip. See
separate gun or tip manual.
Relieve pressure. Check and clean
spray tip.
Refill and reprime pump.
Remove and clean, then reinstall.
Remove intake valve and clean.
Check balls and seats for nicks;
replace if necessary. See pump
manual. Strain paint before using to
remove particles that could clog
pump.
Clean filter.
Follow Pressure Relief Procedure,
page 12, then repair prime valve.
Service pump. See pump manual.
Replace packings. See pump manual.
Also check piston valve seat for
hardened paint or nicks and replace if
necessary. Tighten packing
nut/wet-cup.
What to Do
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