Test 50 - Check Fuel Supply And Pressure - Generac Power Systems 7 kW NG Repair Manual

Section 4.5
Diagnostic Tests
Figure 121. Tachometer
Test Bracket:
A starter motor test bracket may be made as shown in
Figure 122. A growler or armature tester is available from an
automobile diagnostic service supplier.
2.625"
0.5"
DRILL TWO HOLES — 1/2"
FOR STARTER
MOUNTING BRACKET
Figure 122. Test Bracket
Remove Starter Motor:
It is recommended that the starter motor be removed from
the engine when testing starter motor performance. Assemble
starter to test bracket and clamp test bracket in vise, Figure 123.
Testing Starter Motor:
1. A fully charged 12 volt battery is required.
2. Connect jumper cables and clamp-on ammeter as shown
in Figure 123.
3. With the starter motor activated (jump the terminal on the
starter contactor to battery voltage), note the reading on
the clamp-on ammeter and on the tachometer (rpm).
Note: Take the reading after the ammeter and tachometer
are stabilized, approximately 2-4 seconds.
4. A star ter motor in good condition will be within the
following specifications:
Minimum rpm
Maximum Amps
Page 122
METAL STOCK
1/4" THICK STEEL
3.5"
1.0"
4"
12"
DRILL TWO HOLES — 1/2"
FOR MOUNTING TACHOMETER
TAP FOR 1/4-20 NC SCREWS
V-twin Single Cylinder
3250 4500
62 9
STARTER
CONTACTOR
STARTER
MOTOR
TACHOMETER
VISE
Figure 123. Testing Starter Motor Performance
2"
TEST 50 – CHECK FUEL SUPPLY AND
Discussion
The air-cooled generator was factory tested and adjusted
using natural gas as a fuel. If desired, LP (propane) gas may
be used. However, when converting to propane, some minor
adjustments are required. The following conditions apply for a
unit to operate correctly:
• An adequate gas supply and sufficient fuel pressure must be
available or the engine will not start.
• Minimum recommended gaseous fuel pressure at the gen-
erator fuel inlet connection is 5 inches water column for
natural gas (NG) or 10 inches water column for LP gas.
• Maximum gaseous fuel pressure at the generator fuel inlet
connection is 7 inches water column for natural gas or 12
inches water column for LP gas.
• When propane gas is used, only a "vapor withdrawal" system
may be used. This type of system utilizes the gas that forms
above the liquid fuel. The vapor pressure must be high enough
to ensure engine operation.
• The gaseous fuel system must be properly tested for leaks
following installation and periodically thereafter. No leakage is
permitted. Leak test methods must comply strictly with gas
codes.
 Gaseous fuels are highly explosive. Do not use flame
or heat to test the fuel system for leaks. Natural gas is
lighter than air, and tends to settle in high places. LP
PART 4
ENGINE/DC CONTROL
CLAMP ON
AMP METER
PRESSURE
12 VOLT
BATTERY