Troubleshooting Guide - Gaseous-Fueled Engines
The troubleshooting guide that followsis designed to outline common problems, potential causes, and repair action related
specifically to gaseous-fueled engines.
Troubleshooting of common engine components and systems, such as the ignition system,is listed in the Gasoline-Fueled
Troubleshooting Chart. This troubleshooting chart serves toidentify potential causes of problems related directly to the
liquified petroleum gas (LPG) and natural gas (NG) components of the engine.
NOTE: Always have a certified LPG/NG technician perform repairs on gaseous fuel systems.
Gaseous-Fueled Engine Troubleshooting Chart
Gaseous-Fueled Engine Troubleshooting Chart
Problem Potential Cause Action
Out of fuel Refill the tank (LPG)
Fuel supply shut off Open fuel supply
Low fuel pressure Check the fuel pressure. Adjust fuel
pressure at the regulator and verify
adequate pipe size for the application
Filter or vacuum lock-off is not opening Check for proper operation of all fuel lock-
off (safety) devices. If electronically actuated,
check for dead battery or blown fuse. Replace
lock-off device if it is not functioning properly.
Vacuum leak in the vacuum lock-off device Replace vacuum line, tighten clamps
or replace vacuum lock-off if damaged.
Faulty fuel regulator/valve Check fuel regulator/valve operation
Incorrect fuel mixture adjustment Inspect fuel mixer for damage
or debris. Replace if necessary
Engine is hard to start or will not start
Incorrect controller settings (standby home
generator application)
Enter the correct controller
settings. See generator manual
for proper procedures and steps
Plugged vent ports on the fuel regulator/valve Inspect the fuel regulator/valve vent ports
Low fuel pressure Check the fuel pressure. Adjust fuel
pressure at the regulator and verify
adequate pipe size for the application
Plugged fuel filter Replace fuel filter
Kinked or obstructed fuel hose Remove the kink and/or replace the fuel hose
Fuel tank is too small for application (LPG) Appropriately size the fuel tank for the engine
horsepower and lowest ambient temperature
Fuel transfer switch is in the wrong position Set the transfer switch to the
correct fuel used. Either LPG or NG
Incorrect fuel mixture adjustment Inspect fuel mixer for damage
or debris. Replace if necessary
Air leak in the fuel line from secondary regulator
to mixer/carburetor
Tighten clamps and
connections or replace the line
Holes, tears or damage in the diaphragm of the
secondary regulator
Replace damaged components
Engine does not accelerate from low speed or
high speed or run smoothly when under load
Debris and contamination on inlet needle of
regulator
Clean system of debris and
contamination. Add fuel filter
Wrong type of propane tank - set up for liquid
withdrawal
Replace the fuel tank or change
to the vapor withdrawal port
Fuel tank is positioned incorrectly Fuel tanks have a receptacle for a locator
pin that orients the tank for a specific
withdrawal. Pin may be in the wrong
location or missing. Reposition tank
Fuel tank is overfilled Fill to labeled tank capacity only
Fuel tank is too small, especially if the ambient
temperature is low
Increase the size of the fuel tank to
increase the vaporization rate of the
fuel. Consult with local gas supplier
Frost forming on the regulator or on the fuel
line - liquid (not vapor) entering the system
Restriction within the fuel line Remove restriction or replace damaged part
Gas will not stop flowing
after engine is stopped
Regulator is not adjusted properly Consult equipment service manual
for proper procedures and steps
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