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

**[Step 1] TEST 28: Check Fuel Supply**
Begin by verifying the fuel level in the supply tank. In RV installations, the generator's pickup tube is often shorter than the vehicle's, causing the generator to run out of fuel while the vehicle still has a 1/4 tank remaining. Ensure fuel is fresh, as stale gasoline causes hard starting. For LPG units, ensure the primary regulator delivers 11 inches water column and does not exceed 14 inches water column.
- **Results:** If fuel is low or stale, replenish with fresh fuel. If fuel supply is confirmed good, proceed to **Test 29**. (Page 50)

**[Step 2] TEST 29: Check Wire 14 Power Supply**
The Engine Controller must deliver battery voltage to Wire 14 to operate the fuel pump and solenoid. Locate the 4-tab terminal connector. Connect a VOM positive (+) lead to the connector and negative (-) to ground. Crank the engine and check for 12 VDC. If voltage is absent, check Terminal J2 on the Engine Controller Circuit Board.
- **Results:** If battery voltage is present at the connector, proceed to **Test 19**. If voltage is missing at the connector but present at J2, repair Wire 14. If voltage is missing at J2, replace the Engine Controller Circuit Board. (Page 51)

**[Step 3] TEST 19: Test Primer Switch**
The primer switch is in series with the Wire 14 circuit; a failure here prevents both priming and starting. Check for battery voltage at Wire 15 of the switch. Then, check for voltage at Wire 14 while cranking. Finally, check Wire 14A while the switch is in the "PRIME" position.
- **Results:** If battery voltage is present on Wire 14 but not on 14A during priming, replace the Primer Switch. If the switch shows no continuity between Wire 14 and 14A when not actuated, replace the switch. If the switch passes all voltage and continuity checks, proceed to **Test 20**. (Page 44)

**[Step 4] TEST 20: Check Fuel Pump Operation**
Verify the fuel filter is not clogged and fuel reaches the inlet. Disconnect the fuel hose at the pump and activate the primer; fuel should flow. If it does not, check for ground continuity on Wire No. 0 at Connector 2. Measure fuel pump coil resistance between the Red and Black wires at the pump.
- **Parameters:** Fuel pump coil resistance specifies about **29.5 kΩ**. Current draw is **1.4 amperes MAXIMUM**. Pump outlet pressure should be **2.0 to 3.5 psi**.
- **Results:** If resistance is incorrect or a short to ground is found, replace the Fuel Pump. If the pump tests good, proceed to **Test 31**. (Page 45)

**[Step 5] TEST 31: Check Fuel Solenoid (Gasoline Units)**
With the Start-Stop switch at "START," the solenoid at the base of the carburetor bowl must energize. Use a jumper across the primer switch terminals to manually activate it; you should hear/feel a click. If it fails, check for battery voltage on Wire No. 14 (Connector 3, Pin 2) and ground continuity on Wire No. 0.
- **Parameters:** Solenoid coil resistance is approximately **30.1 ohms**. Current draw is approximately **418 milliamps (0.418 amps)**.
- **Results:** If the solenoid has power and ground but does not actuate, replace the Fuel Solenoid. If it operates correctly, proceed to **Test 32**. (Page 52)

**[Step 6] TEST 32: Check Ignition Spark**
Disconnect the high tension lead and use a spark tester grounded to the cylinder head. Crank the engine rapidly.
- **Parameters:** Engine must be cranking at **350 rpm** or more.
- **Results:** If spark is strong and consistent, proceed to **Test 33**. If there is no spark, weak spark, or intermittent spark, proceed to **Test 34**. (Page 53)

**[Step 7] TEST 33: Check Spark Plug**
Remove and inspect the spark plug for fouling or damage.
- **Parameters:** Set gap to **0.030 inch (0.76mm)**. Recommended plug is **Champion RC14YC**. Section 10 specifies **0.03 inch** (Page 90).
- **Results:** Clean, regap, or replace the plug. If the plug is good, proceed to **Test 36**. (Page 53)

**[Step 8] TEST 34: Check Ignition Coil**
Disconnect Wire No. 18A at the bullet connector and retest spark. If spark returns, the issue is a grounded Wire No. 18 or the Engine Control Board. If spark is still absent, measure coil resistance.
- **Parameters:** Wire No. 18A to ground should be approximately **1.5 kΩ**. High tension lead to ground should be approximately **16 kΩ**.
- **Results:** If the coil fails resistance tests or shows no spark despite passing tests, replace the Ignition Coil. Also, verify the flywheel magnet can pull a screwdriver tip from **3/4 inch (19mm)** away. If coil is good, proceed to **Test 36**. (Page 54)

**[Step 9] TEST 36: Check Carburetion**
Inspect the carburetor for "varnishing" (stale fuel) or water. Check if the spark plug is wet (overchoking/stuck valve) or dry (clogged filter/leaking gaskets).
- **Results:** If the carburetor is fouled, clean with approved cleaner and blow dry with compressed air. If carburetion is functional, proceed to **Test 37**. (Page 55)

**[Step 10] TEST 37: Check Choke Solenoid**
During cranking, the choke solenoid should cyclically pull in (2 seconds ON, 2 seconds OFF). Check for cyclic battery voltage on Wire No. 90.
- **Parameters:** Choke solenoid resistance specifies approximately **3.7 ohms**. Current draw is **3.4 amps**. Pre-choke gap (not actuated) should be **1/8 Inch**.
- **Results:** If voltage is missing, check Wire No. 90 or the ECB. If the solenoid is defective, replace it. If the choke system is good, proceed to **Test 35**. (Page 56)

**[Step 11] TEST 35: Check Valve Adjustment**
Ensure valve lash is set at room temperature with the piston at TDC compression.
- **Parameters:** Intake Valve: **0.001-0.0022 (0.03-0.056)** inches. Exhaust Valve: **0.0018-0.003 (0.046-0.07)** inches. Rocker arm jam nut torque specifies **72 inch-pounds** (Section 7) [Note: Section 10 specs 96 in-lbs].
- **Results:** If the engine still fails to start after adjustment, check for a sheared flywheel key. If timing is correct, proceed to **Test 38**. (Page 55)

**[Step 12] TEST 38: Cylinder Leak Down / Compression Test**
Perform a leak-down test at **80 psi** regulated pressure. Follow with a compression test.
- **Parameters:** **20 percent** leakage is acceptable. MINIMUM allowable cold compression for GH-220 is **60 psi**.
- **Results:** Use the location of escaping air (carburetor, exhaust, or breather) to identify internal mechanical failure. (Page 58)

Systematically verify fuel delivery and electrical signals to Wire 14 before proceeding to ignition and internal mechanical compression testing.