Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
Section 55 (Engine Controls - Theory & Operation - Bi-Fuel): Introduction
This article covers basic description and operation of bi-fuel engine performance-related systems and components. Bi-fuel refers to the F150 Pickup 5.4L that can operate using gasoline or alternative fuel. Alternative fuel may be either Compressed Natural Gas (CNG) or Liquefied Petroleum Gas (LPG). Bi-fuel vehicles are either gasoline/CNG, or gasoline/LPG. Bi-fuel systems are separate and have unique components. Alternative fuels are not compatible and should not be mixed or substituted. For illustrations of bi-fuel system components, see Fig 1 and Fig 2 . Read entire article before diagnosing vehicles or systems with which you are not completely familiar.
Switching vehicle operation between gasoline and either CNG or LPG is performed using ALT/GAS fuel switch inside vehicle before ignition is turned on. If vehicle runs out of alternative fuel, system will automatically switch to gasoline operation.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.