Test 55 - Check For Ignition Spark - Generac Power Systems 7 kW NG Repair Manual

ENGINE/DC CONTROL
9. With the generator r unning at a rated speed of
approximately 60 Hz, verify that the choke is energized
and holding the choke plate open.
10. Repeat Step 2; however, once the unit star ts,
manually hold the choke open while taking the voltage
measurement.
Results
1. If the VOM did NOT indicate battery voltage in Step 5 and
wire CONTINUITY was good, replace the controller.
2. If the VOM did NOT indicate approximately 3.7 ohms in
Step 7, replace the choke solenoid.
Procedure: 8kW
1. Refer to Figure 130 for location and function of choke
solenoid. Turn off the fuel supply to the generator. Set
the AUTO-OFF-MANUAL switch to the MANUAL position.
While cranking, the choke solenoid should pull the choke
plate closed. If the choke solenoid does not pull in, verify
that the choke can be manually opened. There should be
no binding or interference.
2. Disconnect the choke solenoid.
3. Set a Volt-Ohm-Milliammeter (VOM) to measure DC
voltage.
4. Refer to Figure 133. Connect the positive meter test lead
to Pin 1 (Wire 56) of the female side of the CS connector
going to the control panel and connect the negative meter
test lead to Pin 2 (Wire 90).
90 56
2 1
FEMALE SIDE
Figure 133. CS Choke Solenoid Connector
5. Set the AUTO-OFF-MANUAL switch to MANUAL. While
cranking, the VOM should indicate battery voltage.
a. If the VOM did NOT indicate battery voltage, verify
CONTINUITY of Wire 90 between the connector Pin
1 J4 (Wire 90) and verify CONTINUITY of Wire 14
between the connector Pin 9 J4 (Wire 56). Repair or
replace any wiring as needed.
b. If the VOM indicated battery voltage, proceed to Step 6.
6. Set a VOM to measure resistance.
PART 4
56 90
1 2
MALE SIDE
7. Connect one meter test lead to Pin 1(Wire 56) on the male
side of the CS connector and the other meter test lead to
Pin 2 (Wire 90), measure and record the resistance.
8. Reconnect the choke solenoid.
9. With the generator r unning at a rated speed of
approximately 60 Hz, verify that the choke is de-energized
and the choke plate is open.
Results
1. If the VOM did NOT indicate battery voltage in Step 5 and
wire CONTINUITY was good, replace the controller.
2. If the VOM did NOT indicate approximately 3.7 ohms in
Step 7, replace the choke solenoid.
TEST 55 – CHECK FOR IGNITION SPARK
Discussion
If the engine cranks but will not start, one cause might be that
an ignition system failure has occurred. A special spark tester
can be used to check for ignition spark.
Figure 134. Spark Tester
Procedure
1. Turn off the fuel supply to the generator.
2. Remove spark plug leads from the spark plugs.
3. Attach the clamp of the spark tester to the engine cylinder
head. Refer to Figure 135.
4. Attach the spark plug lead to spark tester terminal.
5. Set the AUTO-OFF-MANUAL switch to the MANUAL.
6. While the engine is cranking, observe the spark tester. If
spark jumps the tester gap, you may assume the engine
ignition system is operating satisfactorily.
Note: The engine flywheel must rotate at 350 RPM (or
higher) to obtain a good test of the solid-state ignition
system.
7. To determine if an engine miss is ignition related, connect
the spark tester in series with the spark plug wire and
spark plug (Figure 136). Then, crank and star t the
engine. A spark miss will be readily apparent. If spark
jumps the spark tester gap regularly, but the engine miss
continues, the problem is in the spark plug or in the fuel
Section 4.5
Diagnostic Tests
Page 127