Generac Power Systems NP-40G - Manual (Page 111)

Section 7.2- ENGINE DC CONTROL SYSTEM
Test 11- Test Starter Contactor
DISCUSSION:
See "Starter Contactor" on Page 6.3-2. Replace
Starter Contactor If bad.
Test 13- Check Fuel Supply
DISCUSSION:
If the engine cranks but won’t start, don’t overlook
the obvious. The engine won’t start without fuel.
Test 12- Test Start-Stop Switch
DISCUSSION:
Engine cranking and startup are initiated when
the Start-Stop switch Is held at "START" to ground
Wire 17.
Engine shutdown is normally initiated when the
Start-Stop switch is set to "STOP" to ground Wire
18.
A defective switch can prevent normal startup or
normal shutdown.
TEST PROCEDURE:
Check fuel level.
RESULTS:
1. If fuel level is low, replenish fuel supply.
2. If fuel quantity is good, go to Test 14.
Test 14- Check Fuel Filter
Refer to Section 3.3.
TEST PROCEDURE:
1. Carefully Inspect Wire 0 (Ground) between the
Start-Stop switch and the ground terminal. Repair,
reconnect or replace the wire if necessary.
2. Disconnect Wire 17 from its terminal on the
Start-Stop switch. Connect Wire 17 to a clean frame
ground. The engine should crank.
3. Start the engine, using the Start-Stop switch or
by grounding Wire 17.
4. Stop the engine by holding the Start-Stop switch
at “STOP". If engine will not shut down with switch
at “STOP", ground Wire 18 to stop engine.
RESULTS:
1. if engine cranks when Wire 17 Is grounded, but
won’t crank with Start-Stop switch, replace the
Start-Stop switch.
2. if engine stops when Wire 18 is grounded but will
not shut down with Start-Stop switch, replace the
Switch.
3. If engine will not crank when Wire 17 is grounded,
replace the Engine Controller circuit board.
4. If engine will not stop when Wire 18 is grounded,
replace the Engine Controller circuit board.
Test 15- Check Ignition Spark
Refer to Section 6.4, "ENGINE IGNITION SYS­
TEM".
Test 16- Check Spark Plug
DISCUSSION:
A badly fouled spark plug can prevent the engine
from starting. A defective spark plug may allow the
engine to be started, but rough operation or an
"engine miss" may be observed.
A commercially available spark tester can be
used to check for ignition spark. When the spark
tester is connected in series with the spark plug
and its high tension lead, the cause of an engine
miss can be narrowed down to either (a) the ignition
system, or (b) the spark plug or fuel system. Use
of the spark tester is discussed in Test 16.
TEST PROCEDURE:
Remove the spark plug.
Clean by scraping or wire
brushing and by using a
commercial solvent. DO
NOT BLAST CLEAN THE
PLUG. Set spark plug gap
to 0.030 inch (0.76mm). Re­
place spark plug if badly
fouled, if ceramic is
cracked, or if damaged.
RESULTS:
1. Clean and regap or replace spark plug as
necessary.
2. If spark plug is good but engine will not start,
go to Test 3.
3. If spark plug is good but engine misses or runs
rough,, go to Test 23.
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