Lpg Or Ng Fuel Systems, Velocity Governors; Stopping The Engine; Power Loss At Higher Elevations - Carburetion & Turbo Systems Vortec 5700 Operation And Maintenance Manual

LPG OR NG FUEL SYSTEMS, VELOCITY GOVERNORS
Turn on the gas supply to the engine. Turn the ignition key to the
START
position. After the engine
starts, release the key to the
ON
position.
STOPPING THE ENGINE
Following normal operating conditions, lower the engine speed to idle, pushing the throttle cable
in on mechanical systems, or with electronic systems, placing the Hi 1 Lo switch in the Lo
position.
Run the engine for a few minutes at the idle to allow the coolant system to cool down before
turning the ignition to the OFF position.
Warning: Avoid injury when checking the Hot Engine. Allow the engine to cool down
before removing the radiator cap.
Caution: Before restarting the engine ensure that both the coolant system and the engine
oil level have been checked and refilled if necessary.
POWER LOSS AT HIGHER ELEVATIONS
All engines will experience power loss when operated at elevations above sea level, unless they
are turbocharged or supercharged. Turbochargers and superchargers are mechanical pumps that
put extra air into the engine to make up for the lower air density at higher elevations.
Carbureted Engines (Includes LPG and NG Systems): Carbureted engines will lose power
for two reasons. First, power is reduced 3.5% for each 1000 feet the engine is operated above
sea level, due to the decreased air density. With less dense air, the engine receives less oxygen
to burn the fuel. The engine power is decreased in direct proportion to the reduction of available
oxygen. Second, the reduced oxygen causes the fuel mixture to have too much fuel for the
available oxygen. This is a rich mixture (rich with fuel) and not only causes the engine to
produce sooty black exhaust, but also causes additional loss of power and premature spark plug
fouling. Engines that are operated over 3000 feet of elevation that exhibit black smoke or
produce less than optimum power should have the fuel system re-calibrated.
Caution: Engines re-calibrated for high elevations will run lean at lower elevations. Lean
running can burn valves, will reduce valve and valve seat life and can cause engine
overheating. Failures caused by these problems are not covered under warranty.