Fuel Systems What Fuel Pumps Carburetors Electronic Fuel

Fuel Systems

What? �Fuel Pumps �Carburetors �Electronic Fuel Injection (EFI)

Purpose �Mix air and fuel together �Adjust to different engine operating conditions �Idle �Acceleration �Starting �Part throttle �Wide open

Why do we need Fuel pumps? �Cars are not gravity fed

Fuel Filter �Filters gasoline between the tank and the pump

Mechanical Fuel Pump �Driven by the Camshaft �Easy to replace (location)

Electronic Fuel Pump �Not controlled by the camshaft �Usually a pain too replace �Do not run dry!!!!!

Carburetor �The Mouth of the engine �We need air and fuel for combustion �Used until 1990

�Air �Fuel �Float �Choke �Throttle

�Air �Fuel �Float �Choke �Throttle

Fuel injection �Better fuel efficiency �Modernly used �More efficient in general (power)

How EFI Works Input Section Engine sensors Processing Section Computer Output Section Fuel quantity Idle speed 12

�Mass Air Flow (MAF) ØEngine speed sensor ØThrottle position sensor ØCoolant temperature sensor ØAir temperature sensor ØEngine load sensor ØOxygen sensor

Sensors � 02 (exhaust)

Throttle Body Injection �Old (Transition stage) �Bolt on

Port Injection �Modern �Fuel rails �High pressure (35 psi)

Direct Injection �Injector is inside of the combustion chamber �Has to withstand high heat and pressure

New Technology �Nissan GTR

�Fuel Systems Quiz on Thursday!