Generac Power Systems 941-2 - Manual (Page 126)

Section 7.2
ENGINE DC CONTROL SYSTEM / AC TROUBLESHOOTING
ENGINE COMPRESSION PRESSURE
NOMINAL PRESSURE: 60 psi
MINIMUM ALLOWABLE: 55 psi
NOTE: Full compression pressure cannot be
obtained at cranking speeds, due to the action of
a compression release mechanism.
RESULTS:
If compression is poor, look for one or more of the fol-
lowing possible causes:
1. Loose cylinder head bolts.
2. Failed cylinder head gasket.
3. Burned valves or valve seals.
4. Insufficient valve clearance.
5. Warped cylinder head.
6. Warped valve stem.
7. Worn or broken piston ring(s).
8. Worn or damaged cylinder bore.
9. Broken connecting rod.
TEST 26- TEST OIL PRESSURE SWITCH
DISCUSSION:
See Section 6.5, "ENGINE SHUTDOWN FEATURES.”
TEST PROCEDURE:
See Section 6.5.
If necessary, connect an external oil pressure gauge
to the oil pressure switch port.
RESULTS:
1. Replace oil pressure switch if it is defective or repair Wire 85
circuit as necessary.
2. If oil pressure is actually low as indicated by the external
gauge, see Section 5.1, "ENGINE OIL SYSTEM".
3. If oil pressure is good and oil pressure switch is good, go to
Test 27.
TEST 27- TEST OIL TEMPERATURE SWITCH
DISCUSSION:
See Section 6.5, "ENGINE SHUTDOWN FEATURES.”
TEST PROCEDURE:
See Section 6.5.
RESULTS:
NOTE: The generator will shutdown if the 12-pin
connector is disconnected and the circuit breaker
is turned on. In order to perform the running
diagnostic tests, you must jump pin #10 to pin
#11. This will enable the unit to continue to run
with the circuit breaker turned to the “ON” posi-
tion (See Figure 10 on page 7.2-17).
TEST 28 - DC LINK VOLTAGE TEST
1. Disconnect the 12-pin connector from the inverter. Disconnect
the Red-Black-Blue-Green DC Link wires from the inverter.
Note: Cap the DC Link wires with a wire nut for
safety.
2. On units with A6060 circuit board revision “D” or higher soft-
ware, jump pin #10 to pin #11 on the 12-pin cable previously
removed from the inverter. The 12 position cable should be
connected to the 12-pin socket on the generator control panel.
This will enable the generator to run with CB1 turned ON.
3. Turn CB1 to ON position. Start generator. The engine should
run at approximately 3300 rpm.
4. Set VOM to DC. Measure DC Link voltage between the Red
and Blue wires, place Red test lead to red wire and Black test
lead to the Blue wire. DC voltage should be approximately 375
VDC. Measure DC link voltage between the Red wire and
Black wire, place Red test lead to Red wire and Black test lead
to Black wire, DC voltage should read +175 VDC. Measure
DC link voltage between the Blue wire and the Black wire,
place Red test lead to Blue wire and Black test lead to Black
wire. DC voltage should read –175 VDC.
Page 7.2-16