Guardian Technologies 4759 Test 51 Check Fuel Supply Pressure, Testing Starter Motor Performance

DC CONTROL

PART 4

SECTION 4.4

DIAGNOSTIC TESTS

4.A starter motor in good condition will be within the following specifications:

	Single Cylinder	V-twin
Minimum rpm	800	4500
Maximum Amps	9	50

Figure 15. Testing Starter Motor Performance

TEST 51 - CHECK FUEL SUPPLY AND

PRESSURE

DISCUSSION:

The air-cooled prepackaged generator was factory tested and adjusted using natural gas as a fuel. If desired, LP (propane) gas may be used. However, when changing over 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 11 inches water column (6.38 ounces per square inch).

❏Maximum gaseous fuel pressure at the generator

fuel inlet connection is 14 inches water column (8 ounces per square inch).

❏When propane gas is used, only a "vapor withdrawal"

system may be used. "This type of system utilizes the gas that form above the liquid fuel the vapor pressure must be high enough 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, TENDS TO SETTLE IN HIGH PLACES. LP (PROPANE) GAS IS HEAVIER THAN AIR, 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 11 - 14 inches water column as measured with a manometer, or 6.38-8.00 ounces per square inch as measure with a pressure gauge.

The fuel pressure can be checked using a pressure tester kit (Generac p/n 0C7977). See Figure 16 for the gas pressure test point on the fuel regulator.

NOTE: Where a primary regulator is used to establish fuel inlet pressure, adjustment of that regulator is usually the responsibility of the fuel supplier or the fuel supply system installer.

RESULTS:

1.If fuel supply and pressure are adequate, but engine will not start, go on to Test 53.

2.If generator starts but runs rough or lacks power, repeat the above procedure with the generator running and under load. The fuel system must be able to maintain 11”-14” water column at all load requirements. If proper fuel supply and pressure is maintained, go to Test 55.

Figure 16. Air Cooled Engine Fuel System

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