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

**TEST 32: CHECK IGNITION SPARK**
Begin by disconnecting the high tension lead from the spark plug and attaching it to a spark tester (Part No. 0C5969). Ground the tester to the cylinder head and crank the engine at a speed of 350 rpm or more. If a spark jumps the gap, the ignition system is likely functional. To rule out an engine miss, connect the tester in series between the lead and the plug while the engine runs; if the spark is regular but the miss persists, the issue is the plug or fuel system.
* **If GOOD:** Proceed to TEST 33.
* **If NO SPARK or INTERMITTENT SPARK:** Proceed to TEST 34. (Page 53)

**TEST 33: CHECK SPARK PLUG**
Remove the spark plug and inspect for fouling, cracked ceramic, or wear. Clean with solvent only (do not blast clean). Check that the gap is set to 0.030 inch (0.76mm). Use a Champion RC14YC replacement if necessary.
* **If plug is BAD:** Clean and regap or replace spark plug.
* **If plug is GOOD:** Proceed to TEST 36. (Page 53)

**TEST 34: CHECK IGNITION COIL**
1. Disconnect Wire No. 18A at the Bullet Connector and repeat TEST 32. If spark returns, there is a ground fault.
2. Disconnect J1 from the Engine Control Board (ECB). Measure resistance from Wire No. 18A (Pin J1-4) to frame ground. Reading must be Infinity.
3. Check for battery voltage at Wire No. 15 (J3 Terminal) to ground. Ensure Wire No. 15 is at J3 and Wire No. 14 is at J2.
4. Measure resistance between Wire No. 18A (coil side) and frame ground. It should be approximately 1.5 kΩ.
5. Measure resistance between the high tension lead and frame ground. It should be approximately 16 kΩ.
* **If Steps 4 or 5 fail by a high margin:** Replace Ignition Coil.
* **If Flywheel Key is sheared:** Replace key to correct timing. (Page 54)

**TEST 36: CHECK CARBURETION**
Ensure the tank has fresh fuel (less than 30 days old) and all valves are open. Inspect the spark plug: if wet, check for overchoking, water in fuel, or a stuck intake valve; if dry, check for a failed fuel pump, plugged filters, or leaking gaskets. Verify the generator rotor is not contacting the stator and the unit is not starting under load.
* **If carburetor is varnished:** Clean with approved cleaner, blow dry with compressed air, or replace.
* **If problem persists:** Proceed to TEST 37. (Page 55)

**TEST 37: CHECK CHOKE SOLENOID**
Crank the engine and verify the choke solenoid pulls in cyclically (2 seconds ON, 2 seconds OFF).
1. **Pre-Choke Adjustment:** With the solenoid deactivated, the choke plate should be 1/8 Inch from full open.
2. **Solenoid Adjustment:** Loosen bracket screws and align carburetor throttle shaft "Edge A" parallel to body "Edge B."
3. **Electrical:** Test for cyclic battery voltage at Wire No. 90 during cranking. Measure resistance between Wire No. 90 and Wire No. 0 at the solenoid; it should be approximately 3.7 ohms.
* **If GOOD:** Proceed to TEST 41.
* **If BAD:** Adjust, repair, or replace as necessary. (Page 56)

**TEST 41: TEST CHOKE HEATER**
Allow the engine to run for five minutes; the Bi-Metal strip should open the choke plate fully. If it stays closed, measure for battery voltage at Wire No. 14 (Connector 1, Pin 3) to ground during start. Check resistance of the Choke Heater; it should be approximately 37 ohms (±20%).
* **If resistance is incorrect or Bi-Metal strip fails to move with voltage present:** Replace Choke Heater.
* **If Choke Heater is GOOD:** Proceed to TEST 35. (Page 60)

**TEST 35: CHECK VALVE ADJUSTMENT**
Adjust valve lash when the engine is at room temperature and the piston is at Top Dead Center (TDC).
* **Intake Valve Clearance:** 0.001-0.0022 (0.03-0.056) [Note: Procedure specifies 96 in-lbs for Rocker Arm Jam Nuts on Page 91; Page 55 specifies 72 inch-pounds]. Use the Section 7 value of 72 inch-pounds for the Jam Nut.
* **Exhaust Valve Clearance:** 0.0018-0.003 (0.046-0.07).
* **Results:** If valves are adjusted to spec and problem persists, check flywheel key (TEST 34) or proceed to TEST 38. (Page 55)

**TEST 38: CYLINDER LEAK DOWN / COMPRESSION TEST**
Perform a leak down test at 80 psi at TDC. Leakage should not exceed 20 percent. Listen for air at the carburetor (Intake Valve), exhaust (Exhaust Valve), or breather (Piston Rings). For a standard compression test, crank the engine until the gauge stabilizes.
* **Minimum Allowable Compression (Cold):** 60 psi.
* **If BAD:** Repair or replace head gasket, valves, or piston rings as necessary. (Page 58)

Systematically verify ignition spark and plug gap before addressing fuel delivery and mechanical valve lash to resolve hard starting or rough running.