8-25
LPG Carburetor (Prior to Spec E)
See Figure 8-22. LPG carburetors prior to Spec E
have two adjustment screws that must be properly
set for satisfactory operation. The throttle stop
screw controls how much the throttle plate remains
open when the governor closes the throttle The
main adjustment screw controls the fuel mixture. No
other adjustments are required with an LPG carbu-
retor since there are no float or choke adjustments.
Mixture Screw Adjustment:
The mixture screw
should not be adjusted until the ignition system,
governor, and other fuel system components have
been checked for correct operation. If the carbure-
tor is totally out of adjustment, turn the mixture
screw in until lightly seated. For a preliminary ad-
justment turn the screw out 2 turns.
CAUTION
Forcing the mixture adjustment
screw tight will damage the needle and seat.
Turn in only until light resistance can be felt.
Start the engine and allow it to run for about 15 min-
utes at half load. Figure 8-22 shows the location of
the adjustment screw. Use the following procedure
to adjust:
1. Stop the genset and connect a voltmeter, fre-
quency meter, and load bank to the generator
output leads.
2. Start the genset and apply full rated load. Verify
that the frequency is within 60 0.5 Hz (50
1 on 50 Hz units) and adjust the governor
speed adjustment nut if necessary to obtain re-
quired frequency.
3. Turn the main adjustment screw inward until
voltage or frequency drops and then outward
until voltage or frequency drops again. Set the
main adjustment screw at the point where the
voltage and frequency are highest. If a CO me-
ter is available, follow the manufacturer’s in-
structions for use and adjust the main adjust-
ment screw to obtain 1 to 2 percent CO.
4. Remove the load and verify that frequency is
within 62.5 0.5 Hz (52 0.5 on 50 Hz units).
Adjust governor speed adjustment nut if neces-
sary to obtain required frequency.
5. Pull the governor linkage toward the front of the
genset so that the throttle lever on the carbure-
tor is resting against the throttle stop screw. Ad-
just the stop screw to obtain a setting of 55
1 Hz (45 1 Hz on 50 Hz units).
6. Release the governor linkage and observe the
stability of the genset. Set the voltage and fre-
quency and adjust the sensitivity of the gover-
nor as specified under
Governor
on Page 8-9.
Add and remove a half load several times to
make certain the genset does not bog down or
hunt.
Carburetor problems not corrected by the adjust-
ments may be caused by dirt in fuel passages or
worn internal parts. Under normal conditions, the
carburetor should seldom require cleaning since
LP-gas vaporizes completely before reaching the
carburetor and leaves no residue. However, a bad
fuel supply may allow dirt or oil to collect in the car-
buretor. This may require carburetor cleaning to re-
store satisfactory operation.
Cleaning the carburetor includes complete disas-
sembly, thoroughly cleaning, and replacement of
parts and gaskets.
MAIN ADJUSTMENT
SCREW
THROTTLE
STOP SCREW
FIGURE 8-22. LPG CARBURETOR ADJUSTMENTS
(PRIOR TO SPEC E)
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