169Section 9 Gas Fuel SystemsTP-6356 4/12
9.5 Carburetor/Gas Mixer
Adjustment
Before adjusting the carburetor, verify that the engine
compression and ignition system meet specifications.
Do not adjust the carburetor to compensate for other
engine disorders. If the engine speed is incorrect, adjust
the governor to achieve 1800 rpm (at 60 Hz) or 1500
rpm (at 50 Hz). Adjust the mixer if governor adjustment
alone does not result in the desired engine speed.
Adjusting the carburetor affects the engine air/fuel
mixture. Routine carburetor adjustment is not
necessary. However, if the carburetor is removed or
tampered with, the mixer may require adjustment to
achieve optimum engine performance. Some engines
have sealed mixers that are not adjustable.
9.5.1 Gasoline Carburetor Adjustment
Procedure
Refer to the engine operation manual and/or engine
service manual for gasoline carburetor adjustment
information. Otherwise, use the following procedure to
adjust gasoline carburetor fuel system.
1. With generator set stopped, turn the main fuel and
idle mixture (if used) adjusting needles in
(clockwise) until they bottom lightly. Do not force.
2. Preliminary Setting: Turn main fuel adjusting
needle out (counterclockwise) 1 1/2--2 1/2 turns.
Turn the idle mixture adjusting needle (if used) out
(counterclockwise) 1/2--1 turn. See Figure 9-11.
1
2
3
TP-5750-3
1. Fuel adjusting screw
2. Lean
3. Rich
Figure 9-11 Fuel Mixture Adjustment, Typical
3. Place the generator set master switch to the RUN
position to start generator set. Run at
approximately half load. The engine must be warm
before making final settings.
4. Apply 3/4 to full load to generator set.
5. Final Setting: Rotate the main fuel adjusting
needle until the engine runs smoothly at the leanest
setting and then turn the main fuel adjusting needle
out (counterclockwise) an additional 1/4 turn.
6. Place the generator set master switch to the
OFF/RESET postion to stop the generator set.
9.5.2 Gas Mixer Adjustment Procedure
(Typical)
Use the following procedure to adjust the gas mixer.
1. Place the generator set in the RUN position to start
the generator set. Run it at approximately half load.
2. Adjust the engine fuel mixture screw (Figure 9-11)
until the engine runs smoothly.
3. Apply varying loads and readjust the mixer as
necessary to achieve smooth engine performance
at all load levels.
4. Place the generator set master switch to the
OFF/RESET position to stop the generator set.
9.6 Fuel System Maintenance
9.6.1 Gasoline Models ( 20 kW, Ford
LRG-425 Powered only)
Clean or replace the fuel filter at the specified interval.
Service the filters more frequently if the engine runs
roughly, as a clogged fuel filter can cause rough engine
operation. Some models use a disposable inline fuel
filter, which must be replaced. Other models have a fuel
pump with an integral fuel filter that requires cleaning at
the specified interval.
9.6.2 Gaseous Models
Routine service items include draining water/sediment
from piping at petcock or pipe end cap, checking for fuel
leakage at pipe connections, checking flexible sections
for cracking or chafing, and keeping components clean
including fuel regulator vent holes.
A grease or wax residue tends to accumulate in the
piping and fuel regulators over time. If fuel system
problems persist, disassemble the fuel system
components and check for residue buildup. Remove
any residue with a brush and mild detergent.
Additional service for LP liquid withdrawal systems
include servicing the gas supplier or customer-supplied
LP gas filter.
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