Generac 4077 Generator Set

⚠ On all new product make sure the belt tension is inspected before it is installed.

1. Remove all covers and inspect belt for proper tensioning.
2. Turn the two adjusting bolts until the compressed length of the springs is 5/8 inch (16mm).

⚠ Under no circumstances should this adjuster be completely removed.

⚠ A new freeze plug part # D2529 MUST be reinstalled to retain the tamperproof status of the regulator.

Tools: Spark tester, Feeler gauge

1. Check for proper spark using a spark tester.
2. Check for proper fuel supply to the regulator; 11 inches of water column should be available.
3. Check valve lash; valves should be set between .002-.004.
4. Verify the regulator is not stuck (manually choke the unit to start, then retry).
5. Remove the freeze plug located directly above the inlet.
6. Unscrew the threaded adjuster to achieve 5mm from the top of the adjuster screw to the top of the threaded casting.
7. Start the generator a number of times until satisfied the condition is fixed.
8. Reinstall a new freeze plug part # D2529 and mark an X across the freeze plug with a permanent marker.

⚠ In multiple hairpin configurations, one hairpin can fail while the others remain functioning. Note the jumper position so they can be properly reassembled.

Tools: Phillips screwdriver (slip-joint pliers for explosion proof), Needle nose pliers or nut driver, Ohmmeter

1. Disconnect the heater from the power source.
2. For heaters with a thermostat, allow the coolant to cool below the thermostat range or remove the heater from the engine.
3. Check for continuity with an ohmmeter between the element terminals inside the electrical box (remove all wires to avoid a false reading).
4. If there is continuity through the element, check for continuity across the thermostat terminals (if applicable).
5. If there is no continuity between the element or thermostat terminals the heater has failed; determine the cause of failure.
6. If there is continuity through both the element and the thermostat, the heater is fine and the problem is improper installation, faulty wiring or an air pocket.

Tools: Pressure gauge

1. Remove plug or LOS switch from engine and install a pressure gauge.
2. Start and run engine and note how much oil pressure you have.

⚠ New rubber bumper gets placed at base of block right above sump cover, and on the centerline of the starter.

Tools: Feeler gauge

1. Measure the voltage at the starter contactor terminal; verify 11-12 volts DC during cranking.
2. If below 11 volts DC, measure at the battery terminals during cranking; recharge/replace battery if below 11 volts DC.
3. If battery voltage is above 11 volts DC, check for proper battery cable sizing.
4. Manually engage the starter pinion into the ring gear and check for .020-.035 inch backlash, measuring at eight equally spaced locations.
5. Shim or remove shims as necessary using shim kit part number 0D4791.
6. Visually check that the starter motor is perpendicular to the ring gear; replace the starter motor if the mounting bracket is bent.
7. Check position of rectangular rubber bumper part number 0C3794; older units used rubber dimples and should be replaced.

⚠ Record your measurements and include these findings on the Warranty Repair Report or the claim will be rejected.

⚠ Be careful when pushing the SW1 switch, there is LIVE voltage present on the PCB.

1. With Auto/Off/Manual in Auto or Manual, check for battery voltage from wire #15A (J1-10) to wire #0 (J1-13); should be 12-14 VDC.
2. IF STARTER DOES NOT CRANK: measure #56 wire (J1-5) to #0 (J1-13) within 5 seconds of placing unit to manual; should be greater than 10 VDC.
3. If less than 10 VDC, remove #56 wire from J1 housing and re-measure across J1-5 to J1-13; if still less than 10 VDC, replace the board.
4. Also check for a short to ground on wire #56 which could damage the board.
5. IF STARTER CRANKS BUT UNIT DOES NOT COME UP TO SPEED: measure #14 wire (J1-7) to ground (J1-13) while cranking; should be greater than 10 VDC.
6. If less than 10 VDC, remove #14 wire and re-measure J1-7 to J1-13; if still less than 10 VDC, replace the board.
7. IN AUTO - UNIT DOES NOT TRANSFER AFTER UTILITY LOSS & 20 SECOND WARM-UP DELAY: measure #23 (J1-3) and #194 (J1-4); should be greater than 10 VDC.
8. If not, remove #23 and #194 wires and re-measure J1-3 to J1-4; if less than 10 VDC, replace the board; also check for a short to ground on #194.
9. IN AUTO - UNIT DOES NOT TRANSFER BACK TO UTILITY WHEN UTILITY VOLTAGE IS RESTORED: check voltage between J1-14 (red wire) and J1-15 (#225A wire); should be greater than 12 VAC.
10. If utility is near rated (208 VAC or 240 VAC) and secondary is less than 12 VAC, check transformer wiring; if greater than 12 VAC and still no return, replace the board.

Tools: Audible continuity meter, Air pressure source

1. Apply 20 PSI air pressure to switch.
2. Connect an audible continuity meter to the switch and ground.
3. Release the air pressure and note the pressure when the meter sounds.
4. Accept the part if the switch closes at the specified pressure; reject if it does not.

⚠ If the battery voltage measures greater than 13 volts it should be discharged to less than 12.6 volts.

Tools: Current meter, Voltmeter

1. Set the exercise timer per the Owner's Manual (this sets the PCB to the zero reading).
2. Remove the DC fuse from the control panel.
3. Measure the DC voltage at the battery (+)(-) and record; if greater than 13 volts discharge it to less than 12.6 volts.
4. Measure current across the fuse holder with the fuse removed (current flow should be into the battery, typically in the .5 amp range).
5. If current cannot be measured, reinstall the fuse and measure battery voltage; over ten to fifteen minutes a slow increase should be seen.

⚠ Be careful when pushing the SW1 switch, there is LIVE voltage present on the PCB.

Tools: Non-conductive device (e.g., pencil eraser), Flashlight

1. Remove the DC fuse from the control panel.
2. Open the control panel front (be careful not to short any wiring).
3. Remove the cover from the CMA box.
4. Locate SW1 on the circuit board (76009-A) in the upper right corner.
5. Install the fuse back in the control panel.
6. Put the Auto-Off-Manual switch in the Auto position.
7. Push and hold SW1 with a non-conductive device until the unit starts (about 30 seconds); the unit will run about 20 minutes then shutdown.

⚠ The exerciser will only work in the AUTO mode.

⚠ The exerciser will need to be reset every time the 12-volt battery is disconnected and then reconnected.

⚠ The exerciser WILL NOT work if dip switch 2 (Remote Not Auto) is ON.

1. Verify that the Auto/Off/Manual switch is set to AUTO.
2. Hold down the set timer switch until the generator starts (approximately 10 seconds) and then release.
3. The generator will start and run approximately seven (7) or twelve (12) minutes then shut down on its own; the exerciser is set to run at that time weekly.

⚠ The primary regulator for the propane supply is NOT INCLUDED with the generator.

Tools: Pipe thread sealant

1. Turn off the main gas supply.
2. Remove the three carburetor fuel hoses from the outlet ports of the demand regulator.
3. Disconnect wire #0 and wire #14 from the gas solenoid on top of the demand regulator.
4. Remove the demand regulator from the enclosure by rotating counterclockwise.
5. Remove the small brass hose fitting from the idle circuit port of the regulator housing.
6. Remove the small jet (0D5698A) located in the side of the regulator port on the regulator.
7. Refit the brass hose fitting to the idle circuit port using pipe thread sealant.
8. Identify both adjustment screws (one accessed from the front, one from the back).
9. Reverse procedure steps 1-4 to reinstall the demand regulator.
10. To run on LP fuel, turn both adjuster screws 1/4 turn clockwise.
11. Make minor adjustments to the preset screw settings to achieve maximum power.

⚠ Make sure you have clearance here (new mounting location).

1. Remove M8 bolt from clamp located on the side of engine block.
2. Reposition fuel hose and clamp to new mounting location on the timing belt case cover.
3. Replace M8 bolt and tighten.