Generac Power Systems 7 kW NG, 9 kW NG Test 66 Check Fuel Supply Pressure, Port, Solenoid Removed

Section 4.4

Diagnostic tests

Part 4

DC control

	CLAMP ON
STARTER	AMP METER
CONTACTOR
STARTER
MOTOR
TACHOMETER
VISE	12 VOLT
	BATTERY

Figure 17. Testing Starter Motor Performance

Test 66 – Check Fuel Supply and

Pressure

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 convert- ing to propane, some minor adjustments are required. The following facts apply:

•An adequate gas supply and sufficient fuel pressure must be available or the engine will not start.

•Minimum recommended gaseous fuel pressure at the generator 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.

*DANGER: 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 (PROPANE) GAS IS HEAVIER THAN AIR, AND TENDS TO SETTLE IN LOW AREAS. EVEN THE SLIGHTEST SPARK CAN IGNITE THESE GASES AND CAUSE AN EXPLOSION.

PROCEDURE:

A water manometer or a gauge that is calibrated in “ounces per square inch” may be used to measure the fuel pressure. Fuel pressure at the inlet side of the fuel solenoid valve should be between 5-7 inches water column for natural gas (NG) or 10-12 inches water column for LP gas.

1.See Figures 18, 19 or 20 for the gas pressure test point on the fuel regulator. The fuel pressure can be checked at Port 1 on all fuel regulators, and at Port 3 on 12-20 kW units.

2.With the manometer connected properly, crank the engine. Nominal fuel pressure should be measured. If pressure is not measured while cranking refer back to flow chart.

PORT 1

PORT 2

Figure 18 (8 kW) Gas Pressure Test point

PORT 1

PORT 2

SOLENOID REMOVED

Figure 19 (10 kW) Gas Pressure Test point

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