SECTION
.I:
GENERAL INFORMATION
SYSTEMATIC CHECKi
lf the engine will not stad
and the cause
of malfuncrion is
not €adilyapparen!
perform
a systematic
check in the fo lowing
orderl
1. lgnition
2. Fuel
3. Compression
This
check'up,
performed
in
a systematic manneri
cdn usu-
ally be done
in
a matter of minutes.
lt isthe
quickest
and surest
method of determining
the cause of fiilure.
The basiccheckup
procedure
isthe same
for all engine modeh,
while
any
varia-
tion, by model, wiilbe
shown underthe
subject heading.
CHECK IGNITION:
lf spark does not
occur look for:
.
Shorted ignition,kill
wlre
.
Two cosed
diodes in
ground
wire harness
.
Incorrect
a rmature
air
gap
FIECK
lGNnoN
{ENG NE RUNNING)I
ifengine
runs but misses
during
operation. a
quick
check to
determine if
ignition
is or is not
at fault
can be made by
installing
a spa*
tesler
(Generac
p,t\l
OC5969)
between the
spark
plug
lead
and each
spark
plug,
Figure t-6.
A spark mks
will be
rcadily
apparent
when the
engine is running. tf spark
i5
good
but
engine
misses, check
for a fouled
spark
plL'lg.
CHECK ]GNITION
(FOULED
PLUG OR OTHER
CAUSES):
To
check for a fouled spark
plug
or a nonjunctioning
cylin-
der. attach
the
lpark
tener
(Generac
P/N
OC5969)between
the
spark
plug
lead
and each spark
plug.
Stad and run
engine at
top no lo.d
speed. Now
ground
one spark
plug,
Fig! re t
-7.
The
engineshould
continue to run on the
other cylinder Repeatthis
test with the other
cylnder lf the engine
will not continue
to
run when making
thistest, the
cylinder that ls NOT
grounded
is not functioning
and/orthe
spark
plug
is fouled.
Installa new
spa*
plug
before
prcceeding.
f miss
cont n!es,
problem
may
be carburetion
orcompression. See
Check Calburction,
Check
Compression.
Also see Cy inder
BalanceTest.
Figvre
1-7. Checking
fot Fouled
plugs
CYL NDER EAIANCE TEST
lf the
enqine is hard stadinq,
runs rough,
misses or tacks
power, pertorm
a cylinder
balance test
to determirre
wnerner
boih
cylirdes are ope.ai 19
rc trerr fL lporenlrat.
Tools Requircdi
1. Two
gnition
Teste6
(Cenerac
P/N
OC5969)
Attach
an i9nition
tester betwe€n
the spark
plug
lead
and
each
spark
plug,
Fiqure
1'6.
Stadand run
engine runnln9
attop no load
speed and note
spark at ign
lion teste6. lf the
spa.k is equat
at both
jgniUon
testers,
the
problem
is not igniton
related.
A spark miss
will
be readily apparent. Now
note RPM
of engine. Ground
out one
cylinder by
contacting ignition
tester and a
good grcund
on
engrne, Figufel
8. Note RPM loss.
Then
ground
out the
other
spark
p
ug and note ihe RPNI
loss. lf the difference between
the two cylind€rs does not
exceed 75 RPNI, the amount
ofwork
the two
qlinde|s
are doing should be considered
equal.
figwe
1-6. Running
Check
J'
I
I
I
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