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

### Step 1: TEST 28 - Check Fuel Supply (LP Models)
The first priority is ensuring the fuel delivery system is providing adequate vapor pressure for the generator to function.
* **System Type:** This generator is designed for **vapor withdrawal** systems only. Do NOT use liquid withdrawal type systems.
* **Fuel Pressure:** The primary gas regulator must deliver gaseous fuel to the secondary regulator at approximately **11 inches water column**. Do NOT exceed **14 inches water column**.
* **Flow Rate:** The recommended minimum gas flow rate for all air-cooled QUIETPACT series generators is **67 cubic feet per hour**.
* **Procedures:** Turn the LP supply to the generator on and verify pressure and flow.
* **Results:**
* If LP pressure is **LOW**: Replenish fuel supply or correct the primary regulator sizing.
* If LP pressure is **GOOD**: Proceed to **Test 32**.
*(Page 50)*

### Step 2: TEST 32 - Check Ignition Spark
Testing the ignition system determines if the "hard start" or "rough run" is electrical or fuel-related.
* **Procedure:** Disconnect the high tension lead from the spark plug and connect it to a spark tester (Part No. 0C5969). Ground the tester to the cylinder head and crank the engine rapidly at **350 rpm or more**.
* **Results:**
* If spark jumps the tester gap (GOOD): Proceed to **Test 33**.
* If spark jumps intermittently: The problem may be the ignition coil; proceed to **Test 34**.
* If NO spark or an engine miss is apparent: Proceed to **Test 34**.
*(Page 53)*

### Step 3: TEST 33 - Check Spark Plug
Even if the ignition system produces a spark, a fouled or damaged plug can cause rough running.
* **Procedure:** Remove the spark plug. Clean with solvent (do NOT blast clean). Replace if ceramic is cracked or badly worn. Set gap to **0.030 inch** (**0.76mm**). Use a **Champion RC14YC** (or equivalent).
* **Torque:** When installing, tighten the spark plug to **15 ft-lbs**.
* **Results:**
* If the spark plug is GOOD: Proceed to **Test 35**.
* If the spark plug is BAD: Clean and regap or replace the spark plug.
*(Page 53, 90-91)*

### Step 4: TEST 34 - Check Ignition Coil
This step diagnoses the solid-state (breakerless) ignition system on the GH-220 engine.
* **Procedure 1:** Disconnect **Wire No. 18A** at the bullet connector and repeat the spark test. If spark returns, check the **Engine Control Board (ECB)** and **Wire No. 18A** (Pin J1-4) for a ground fault (should measure **Infinity**).
* **Procedure 2:** Verify **Battery Voltage** on **Wire No. 15** at terminal **J3** on the ECB. Ensure **Wire No. 15** is on **J3** and **Wire No. 14** is on **J2**; if reversed, the unit will not spark.
* **Procedure 3 (Resistance):** Connect negative (-) lead to **Wire No. 18A** (to coil) and positive (+) lead to ground; measure approximately **1.5 kΩ**.
* **Procedure 4 (High Tension):** Measure from the high tension lead (spark plug boot) to ground; measure approximately **16 kΩ**.
* **Checking Flywheel Magnet/Key:** Ensure the magnet pulls a screwdriver tip from **3/4 inch** (**19mm**) away. Inspect the flywheel key; a partially sheared key causes incorrect timing and hard starting.
* **Results:**
* If the coil fails Step 4 or 5 by a high margin, or passes but there is still no spark: **Replace Ignition Coil**.
* If tests pass but timing is suspected: Proceed to **Test 35**.
*(Page 54, 61)*

### Step 5: TEST 35 - Check Valve Adjustment
Incorrect valve lash prevents the proper air/fuel mixture from entering the combustion chamber.
* **Procedure:** Adjust valves with the engine cold and the piston at **Top Dead Center (TDC)** on the compression stroke.
* **Specifications:**
* **Intake Valve:** **0.001-0.0022 (0.03-0.056) inches (millimeters)**.
* **Exhaust Valve:** **0.0018-0.003 (0.046-0.07) inches (millimeters)**.
* **Torque:** Tighten the rocker arm jam nut to **96 in-lbs** (Procedure Specifies **72 inch-pounds**, but Section 10 specifies **96 in-lbs**).
* **Results:**
* If valves are out of spec: Adjust and retest.
* If valves are GOOD: Proceed to **Test 38**.
*(Page 55, 91)*

### Step 6: TEST 38 - Cylinder Leak Down / Compression Test
If the fuel, spark, and valves are correct, internal mechanical integrity must be verified.
* **Compression Test:** Insert gauge into spark plug hole and crank engine. **Minimum allowable compression pressure (Cold Engine - GH-220) is 60 psi**.
* **Leak Down Test:** Set engine to **TDC**, apply at least **90 psi** air source, and adjust tester to **80 psi**. **20 percent** leakage is normally acceptable.
* Air at carburetor: Check **Intake Valve**.
* Air at exhaust: Check **Exhaust Valve**.
* Air at breather: Check **Piston Rings**.
* Air at cylinder head: Replace **Head Gasket**.
* **Results:**
* If mechanicals are BAD: Repair or replace as necessary (check head bolts, gaskets, rings).
* If mechanicals are GOOD: **Check fuel regulator and carburetor**.
*(Page 58)*

Ensure consistent LP vapor pressure of 11 inches water column and confirm engine compression meets the 60 psi minimum requirement before replacing the ignition coil.