2-1
SeCTIoN 2: IGNITIoN
GeNerAl INForMATIoN
Generac GTH/GTV-760/990 OHVI V-Twin engines use a mag-
neto ignition: an ignition coil with a self-contained transistor
module (no moving parts). Two magneto ignition coils are
used, with a flywheel containing a permanent magnet.
NOTE: The magneto ignition system requires a minimum
of 250 RPM to produce a consistent spark.
eNGINe wIrING HArNeSS
The engine wiring harness consists of a ground wire with a
diode for each ignition coil and a separate wire for the carbu-
retor solenoid. The engine ground wires are connected to the
wiring harness provided by the equipment manufacturer.
NOTE: Newer models will have the diodes built into
the ignition coils or spark plug leads. Check the wire
harness. If there are no diodes in the harness, perform
test on the coil ground terminal.
See Figure 2-4.
TESTING GROUND WIRES:
use a Digital Multimeter (Figure 2-1) to test the
ground wires.
The following test will be made with the meter in the Diode
Test position.
In the Diode Test position, the meter will display the forward
voltage drop across the diode(s). If the voltage drop is less
than 0.7 volts, the meter will "Beep" once as well as display
the voltage drop. A continuous tone indicates continuity
(shorted diode) An incomplete circuit (open diode) will be
displayed as "OL."
Figure 2-1. Digital Multimeter
1. Insert RED test lead into
receptacle in meter.
2. Insert BLACK test lead into the “COM” receptacle
in meter.
3. Rotate selector to
(Diode Test) position.
4. Insert RED test lead clip into connector "A" (Figure 2-2).
Leave attached for remainder of test.
5. Touch BLACK test lead probe to terminal "B."
a. If meter "Beeps" once, diode is OK.
b. If meter makes a continuous tone, diode is defective
(shorted). Replace ground harness.
c. If meter displays "OL," diode is defective (open). Replace
ground harness.
6. Now repeat test for terminal "C." Results must be
the same.
7. Replace wiring if defective.
8. If wiring tests good, proceed to IGNITION COILS section
to replace defective coil.
Note: See “Diode Failure Diagnosis”, Figure 2-3.
A
B
C
ENGINE
GROUND
HARNES
S
POSITIVE METER
TEST LEAD
CYL #2
IGNITION
GROUND
WIRE STUD
CYL #1
NEGATIVE METER
TEST LEAD
Figure 2-2. Testing Ground Wire
SwITCH oN
TurNed oFF
CAuSe
Engine Runs
On 1 Cylinder
Shuts Off OK
1 Closed Diode
Engine Runs
(Both Cylinders)
Only One
Cylinder
1 Open Diode
Won't Run
(No Spark)
2 Closed Diodes
Engine Runs
(Both Cylinders)
Engine Won't
Shut Off
2 Open Diodes
Figure 2-3. Diode Failure Diagnosis
2
Содержание GTH760
Страница 28: ...3 12 Notes ...
Страница 46: ...NOTES 6 8 ...
Страница 52: ...Section 8 Lubrication System 8 4 Figure 8 8 Typical V twin Engine Oil Flow Vertical Shaft Engine Shown ...
Страница 60: ...Notes ...
Страница 64: ...Notes ...
Страница 73: ...Notes ...
Страница 74: ...Notes ...
Страница 75: ......
Страница 76: ...Generac Power Systems Inc P O Box 297 Whitewater WI 53190 Part No 0F6923 Printed in USA Revision C 08 13 08 ...