Generac Power Systems 10 kW LP, 13 kW NG, 7 kW NG manual Test 74 Check and Adjust Ignition Magnetos

Section 4.4

Diagnostic tests

Part 4

DC control

WIRE 18 CONNECTION

Figure 32. Wire 18 Connection 10-20 kW Units

2.Depending on engine type, do the following:

a.On V-twin units, remove Wire 56 from the Starter Contactor Relay (SCR). Using a jumper lead, jump 12 VDC from Wire 15B at TB1 (Customer Connection) to the terminal on the SCR from which Wire 56 was removed. The generator will start cranking. As it is cranking, repeat Test 70. Reconnect Wire 56 when done.

b.On single cylinder units, connect a jumper lead from the stud to which Wire 56 is connected on the Starter Contactor (SC) and 12 VDC Wire 15B at TB1 (Customer Connection). The generator will start cranking. As it is cranking, repeat Test 70.

WIRE 18

CONNECTION

Figure 33. Wire 18 Connection 8 kW Units

3.If spark now occurs with Wire 18 removed, check for a short to ground. Remove the J1 Connector from the circuit board.

4.Set a VOM to measure resistance. Connect one test lead to Wire 18 (disconnected in Step 1). Connect the other test lead to a clean frame ground. INFINITY should be measured.

5.Reconnect the J1 Connector to the circuit board.

RESULTS:

1.If INFINITY was not measured in Step 4, repair or replace shorted ground Wire 18 between the J1 Connector from the circuit board to the stud or bullet connector.

2.If INFINITY was measured in Step 4, replace the circuit board and retest for spark.

3.If ignition spark still has not occurred, proceed to Test 74.

Test 74 – Check and Adjust Ignition

Magnetos

DISCUSSION:

In Test 70, a spark tester was used to check for engine ignition. If sparking or weak spark occurred, one possible cause might be the ignition magneto(s). This test consists of checking ohm values across the primary and secondary windings of the magneto and adjusting the air gap between the ignition magneto(s) and the flywheel. The flywheel and flywheel key will also be checked during this test. A diode is installed before the primary winding inside the coil. This is done to inhibit a spark occurring on both magnetos at the same time.

PROCEDURE: Testing Magnetos V-Twin Only

1.Disconnect the J1 connector from the printed circuit board.

2.Disconnect spark plug wires from the spark plugs on cylinder one and two.

3.Set VOM to measure resistance.

4.Connect the positive (red) meter lead to the bolt connec- tor where Wire 18 was disconnected in Step 1. Connect the negative (black) meter lead to a clean frame ground. A resistance of approximately 300K ±10K ohms should be measured. This reading is the primary winding of both coils in parallel.

5.Connect the positive meter lead to the spark plug wire and connect the negative meter lead to a clean frame ground. Approximately 14K ±3 ohms should be measured. This reading is the secondary winding of both coils in parallel. If INFINITY, or a low or high ohm reading is measured, replace the magnetos.

6.Connect the negative (black) meter lead to the bolt connector where Wire 18 was disconnected in Step 1. Connect the positive (red) meter lead to the spark plug wire on cylinder number two. The meter should indicate INFINITY. This step is testing the diodes in both magnetos to ensure they are still functioning.

7.Repeat Step 6 on cylinder two. If INFINITY is not measured, replace the magnetos.

Note: It is recommended to replace Magnetos in pairs.

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