Generac 86640 - Manual (Page 98)

Test 15. Check Engine Control Circuit
Board Wire #14 Output
DISCUSSiON:
During a startup attempt, when the start-stop switch is
set to “Start“, engine control circuit board action must deliver
battery voitage to the Wire 14 circuit. Wire 14 voitage ener­
gizes a fuel solenoid open to aliow fuel flow. On units with
gasoline fuel system, Wire 14 turns on the fuel pump. And,
on units with electronic governor. Wire 14 turns on the gov­
ernor circuit.
The fact that the engine cranks when the start-stop
switch is set to "Start“ is adequate verification that battery
power is available to the engine control circuit board.
PROCEDURE:
Use a VOM to check for batteiy voltage at terminal #9
(Wire 14) of the engine control circuit board when the engine
is being cranked. Battery voltage should be indicated.
RESULTS:
1. If battery voltage is indicated, go to Test 16.
2. If battery voltage is NOT indicated, replace the engine
control circuit board.
Test 16. Check Fuel Valve
DISCUSSION:
Units with gasoline fuel system are equipped with a fuel
solenoid valve that is attached to the gasoline carburetor (see
Part 5 of this Manual).
Units with gaseous fuel system have separately mounted
solenoid valve (see Part 6).
The fuel valve MUST open if fuel Is to be introduced to
the engine carburetor.
Test 17. Check Fuel Pump
DISCUSSION:
This check applies to gasoline fuel systems only, since
gaseous fuel systems do not require a fuel pump. The fuel
pump MUST operate on these systems or the engine will not
start.
PROCEDURE:
See Section 5.2 of this Manual.
RESULTS:
1. Replace fuel pump if defective.
2. If fuel pump is good, go to Test 18.
Test 18. Test Automatic Choke
DISCUSSION:
This test applies to gasoline fuel systems only, since
gaseous fuel systems do not require a carburetor choke. The
automatic choke on gasoline units actuates only during en­
gine cranking.. Choke operation is terminated at the same
time that cranking ends.
PROCEDURE:
1. Crank the engine. During cranking, the choke solenoid
should pull in about every 2 to 5 seconds.
a. If choke solenoid functions normally, go to Test 19.
b. If choke solenoid does NOT pull in while cranking, go to
Step 2.
2. Try adjusting the choke. See "AUTOMATIC CHOKE AD­
JUSTMENT" on Page 5.3-1.
3. Inspect ground wire (No. 0) between choke module and
start-stop switch.
4. Disconnect Wire 90 from choke module and hold it into firm
contact with a clean frame ground. When engine is cranked,
choke solenoid should pull in.
PROCEDURE:
Gasoline Units: Remove the fuel valve from the engine
carburetor. Hold the valve housing into firm contact with a
clean frame ground and set the start-stop switch to "Start".
The valve tip should pull in, indicating that it has been actu­
ated to its open position.
Gaseous Fuel Units: Disconnect the inlet and outlet
lines from the gaseous fuel valve. Apply 12 volts DC to the
valve wires and the valve should open. Remove the 12 volts
DC and the valve should close. Use your mouth to blow
through the valve, to verify valve open and closed conditions.
CAUTION: If 12 volts DC Is available to the gas­
eous system fuel valve, but valve does not appear
to open, be sure to check gaseous fuel pressure
before rejecting the valve. At pressures in excess
of 14 inches water column (1/2 psi), the valve may
not open.________________________________________
RESULTS:
1. Replace fuel valve if it is defective.
2. If fuel valve checks good, go to Test 17.
RESULTS:
1. Repair, replace or reconnect ground wire (Step 3) as
necessary.
2. In Step 4, if choke solenoid pulls in when engine is cranked
and Wire 90 is grounded but does NOT puil in otherwise,
replace the choke module.
3. In Step 4, if choke solenoid does not pull in and does not
actuate normally either, replace the choke solenoid.
Test 19. Check Engine Ignition System
DISCUSSION:
If engine cranks normally but won't start, the ignition system
may be at fault.
PROCEDURE:
Test ignition system. See Part 8 of this Manual.
RESULTS:
1. Repair or replace defective ignition system parts as re­
quired.
2. If ignition system is functioning normally, go to Test 20.
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