Generac Power Systems 5410 Test 25 - Check Fuel Supply, 27 - Typical Propane Gas Fuel System

Section 7

DIAGNOSTIC TESTS

Test 25 – Check Fuel Supply

DISCUSSION (Gasoline Models):

If the engine cranks but won’t start, don’t overlook the obvious. The fuel supply may be low. Many RV gener- ator installations “share” the fuel tank with the vehicle engine. When such is the case, the Installer may have used a generator fuel pickup tube that is shorter than the vehicle engine’s pickup tube. Thus, the generator will run out of gas before the vehicle engine.

PROCEDURE:

Check fuel level in the supply tank. Attach a fresh fuel supply if necessary and restart. Fuel may be stale, causing a hard start.

RESULTS:

1.If necessary, replenish fuel supply.

2.If fuel is good, go to Test 26 (for Problem 7, Section 6).

Go to Test 29 for Problem 8 (Section 6).

DISCUSSION (LPG Models):

LP gas is stored in pressure tanks as a liquid. The gas systems used with these generators were designed only for vapor withdrawal type systems. Vapor with- drawal systems use the gas vapors that form above the liquid fuel in the tank. Do NOT attempt to use the generator with any liquid withdrawal type system.

11 - 14" WATER COLUMN
REGULATOR	PRIMARY
	REGULATOR
CARBURETOR	VAPOR
	WITHDRAWAL
	TANk

Figure 7-27 – Typical Propane Gas Fuel System

Gas pressure delivered to the solenoid valve must be properly regulated by means of a primary gas regula- tor. Mount the primary regulator at the gas tank outlet or in the supply line from the gas tank. The following rules apply:

•For best results, the primary regulator supplies gas- eous fuel to the secondary regulator at 11 inches water column. Do NOT exceed 14 inches water col- umn.

•The installer must be sure the primary regulator is rated at sufficient gas flow to operate the generator plus all other gas appliances in the circuit.

NOTE: Recommended MINIMUM gas flow rate for all air-cooled RV series generators is 67 cubic feet per hour.

If an existing primary gas regulator does not have a sufficient flow capacity for the generator and other gas appliances in the circuit, (a) install a primary regulator with adequate flow rate, or (b) install a separate regulator only and rated at least 67 cubic feet per hour. The inlet side of any pri- mary regulator that supplies the generator must connect directly to a gas pressure tank. Do NOT tee the generator line into a gas circuit feeding other areas.

$CAUTION! Use only approved components in the fuel supply system. All components must be properly installed in accordance with appli- cable codes. Improper installation or use of unauthorized components may result in fire or an explosion. Follow approved methods to test the system for leaks. No leakage is per- mitted. Do not allow fuel vapors to enter the vehicle interior.

LP gas vapors should be supplied to the second- ary regulator inlet at about 11 inches water column (positive pressure). The engine pistons draw air in during the intake stroke (Figure 7-28). This air passes through a carburetor venturi, which creates a low pressure that is proportional to the quantity of air being pumped. The low pressure from the carburetor venturi acts on the regulator diaphragm to pull the diaphragm toward the source of low pressure. A lever attached to the diaphragm opens a valve to permit gas glow through the carburetor.

TO CARBURETOR

GAS IN

Figure 7-28 – LP Gas Carburetion Diagram

Page 51