DeWalt DW168F Manual page 18

pRoBlEM possIBlE CausE soluTIon
Engine will 17.Vacuum leak at Ensure the evaporative system hose from the
not start, carburetor charcoal canister is connected firmly to port
stay running behind carburetor and other evaporative hoses
or only runs are connected firmly. Ensure carburetor is tightly
when choked secured to engine by the two mounting nuts inside
(continued) air cleaner
18. No or low Refer to Compression Test under Perform Test
compression Checks.
19. Dirty air filter Ensure air cleaner is clean and not blocking air from
entering carburetor. Clean if necessary.
Engine will 1. battery is dead Try fully charged battery. Replace battery pack if
not turn (Electric start) needed.
over, engine
Replace pull start rope. Refer to Recoil starter/
2. Recoil pull
seized
assemble Recoil starter under Breakdowns.
starter rope
broken
3. Recoil pull start Remove recoil assembly. Repair or replace as nec-
not engaging essary. Refer to Recoil starter/assemble Recoil
engine starter under Breakdowns.
4. Cylinder filled Remove spark plug and tip engine momentarily. If
with gas. gas pours out hole, carburetor float bowl needle is
stuck open. Clean or replace carburetor. Refer to
Carburetor under Breakdowns for cleaning instruc-
tions.
noTE: when transporting unit fuel valve must be in
Off position, if not flooding will occur."
5. Electric starter Refer to start Mechanism under Perform Test
motor faulty Checks and starter Motor under Breakdowns for
checks.
6. Excessive Ensure choke mechanism operates
carbon buildup correctly.
in head. Engine
With the choke in the fully open position and the
was possibly run
engine running, the choke plate at entrance of the
with choke in
carburetor should be fully open.
closed or partially
On lever chokes move the lever all the way to the
closed position
right
instead of open.
Replace choke mechanism if choke does not
operate in this way or is damaged. Test and verify
compression is correct. Refer to Compression Test
under Perform Test Checks.
7. Internal part With spark plug removed, rotate engine shaft by
failure hand to see if it rotates smoothly. If still locked up,
remove crankcase cover and determine cause.
Refer to Engine will not start, stay running or
Poor 1. Fuel quality
only runs when choked steps 5,6,12 & 13 under
performance, issue or
starting problem/Engine under Troubleshooting.
low power, restriction
running
too fast,
Backfiring
often
pRoBlEM possIBlE CausE soluTIon
Poor 2. Spark arrestor
performance, dirty or clogged
low power,
running
too fast,
Backfiring
often
(continued)
3. worn governor
arm rivet joint
worn carburetor
throttle actuator,
Governor arm
slipping on shaft,
Throttle linkages
bent
High speed
screw has been
tampered with
4. Backfiring often
or air filter
melted, Ignition
coil could be
faulty
18
Clean spark arrestor, refer to spark arrestor under
Maintenance. Run engine briefly without spark
arrestor to verify that was the cause. Reassemble
spark arrestor to muffler. If screen is damaged
replace spark arrestor if screen is damaged.
IMpoRTanT: These products are equipped with
spark-arresting mufflers. It is legally required in
the state of California. It is a violation of California
statutes section 130050 and/or sec tions 4442 and
4443 of the California Public Re sourc es Code,
unless the engine is equipped with a spark arrester,
as defined in section 4442, and maintained in ef fec-
tive working order. Spark arresters are also required
on some U.S. for est Service land and may also be
legally required under other statutes and ordinanc-
es.
If engine is running over 4000 rpm (67Hz), first
ensure all linkages controlling the throttle position
actuate freely without binding over full travel. noTE:
Comparing the old governor linkage to a new
replacement governor linkage may help to deter-
mine if the components in the system are worn or
damaged.
• The riveted joint in governor arm must pivot
freely but not be loose and sloppy.
• If the high speed adjusting screw has been tam-
pered with it can be readjusted, refer to speed/
Governor adjustments under Perform Test
Checks. HOwEVER, if the root cause of the high
speed is due to the governor arm slipping on the
governor shaft, adjusting the speed will give a
false indication of being correct. The speed will
be ok until put under a load, the engine will droop
or bog down. After adjusting the speed, the
unit must be tested using a load bank tester by
gradually applying full rated load. If speed drops
more that 3 Hz, the governor arm has slipped on
the shaft and needs to be reset. To reset gover-
nor arm, refer to speed/Governor adjustments
under Perform Test Checks.
Replace ignition coil. noTE: Coil resistance can
measure ok and still be faulty. It is best to replace
coil in this case.