Generac Quietpact 40G (Gasoline) / 40LP (LP Vapor) Repair Guide

**TEST 21: Check 7.5 Amp Fuse**
The first step in diagnosing a "No Crank" condition is to inspect the panel-mounted 7.5 amp fuse (F1). Engine cranking is impossible if this fuse is blown. Push in on the fuse holder cap, turn counterclockwise, and remove the fuse for inspection. If the fuse element has melted open, replace the fuse. If the fuse is good, proceed to Test 22. (Page 46)

**TEST 22: Check Battery & Cables**
Inspect battery cables and posts for corrosion or looseness. Measure DC voltage at the starter contactor terminal; verify 11-12 volts DC is available during cranking. If voltage drops below 11 volts DC at the contactor, measure at the battery terminals. If battery voltage is below 11 volts DC, recharge or replace the battery. If battery voltage is above 11 volts DC but drops at the starter, check battery cable sizing. You may also use a hydrometer to test the state of charge and condition. If the battery and cables are confirmed good but the engine will not crank, proceed to Test 23. (Page 46)

**TEST 23: Check Power Supply to Engine Circuit Board**
This test confirms if the Engine Controller circuit board is receiving battery voltage.
1. Use a VOM to measure battery voltage between terminal J3 (Wire 15) on the circuit board and frame ground.
2. Measure resistance between Wire No. 0 (Pin J1-12) and frame ground; continuity should be measured.
If battery voltage is NOT present at Step 1, inspect Wire 13 (Starter Contactor to Fuse), Wire 15 (Fuse to Battery Charge Rectifier), and Wire 15 (Rectifier to Circuit Board). If continuity is not present at Step 3, repair Wire No. 0. If voltage and ground are confirmed but the engine will not crank, proceed to Test 24. (Page 47)

**TEST 24: Check Start/Stop Switch**
1. Check ground Wire 0B between the Start-Stop Switch (SW1) and the grounding terminal for continuity.
2. Disconnect Wire 17 from the switch and connect it directly to frame ground. If the engine cranks, the switch is defective and must be replaced.
3. To bench test the switch: remove the 7.5 amp fuse and disconnect Wires 18, 0B, and 17. Check for infinity between the center and outer terminals. When depressed, the switch should show continuity between the center and the terminal being actuated.
If the engine fails to crank when Wire 17 is grounded, use a jumper to ground Wire 17 at Pin J1-6 of the circuit board. If it cranks now, repair Wire 17 between the board and switch. If it still does not crank, proceed to Test 25. (Page 47)

**TEST 25: Check Power Supply to Wire 56**
This test determines if the circuit board is delivering voltage to the starter circuit. Disconnect Wire 56 from the starter contactor and connect a VOM between the wire and frame ground. Actuate the Start-Stop Switch to "START." The meter should indicate battery voltage. If voltage is absent, check Pin J1-1 (Wire 56) directly at the circuit board. If battery voltage is missing at the board during the start command, replace the Engine Controller Circuit Board. If voltage is present at Wire 56 but the engine does not crank, proceed to Test 26. (Page 48)

**TEST 26: Check Starter Contactor**
1. Check for continuity between Wire No. 0 on the starter contactor and frame ground.
2. Momentarily connect a jumper cable across the two large terminal studs of the starter contactor. If the engine cranks, the contactor is defective and must be replaced.
3. Check contactor coil resistance: disconnect Wire 56 and measure between the terminal and frame ground. The procedure specifies a resistance of 3.9 ohms. If continuity (zero ohms/direct short) is measured, a short to ground exists.
If the engine does not crank during the jumper test, proceed to Test 27. (Page 48)

**TEST 27: Check Starter Motor**
Verify the battery is fully charged. Connect a VOM to the starter motor cable connection and motor frame. Actuate the Start-Stop Switch to "START."
1. If battery voltage is present but the motor does not operate, bench test the starter.
2. If the motor engages (bendix travels) but cannot turn the engine, check for mechanical binding of the engine or rotor. If the engine turns slightly, refer to Test 35 to check valve adjustment (compression release).
For a Starter Performance Test at 12 volts DC: MINIMUM MOTOR RPM = 800 and MAXIMUM AMPS = 9. If performance is below these specs, replace the starter motor. Ensure the starter bracket to block bolts are torqued to 18 ft-lbs during reinstallation. (Page 49, 91)

Follow the sequential diagnostic flow from fuse to battery, then through the control circuit and switch, before concluding with contactor or starter motor replacement.