© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Chapter 29 Fuel Delivery Systems

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Fuel Delivery Systems Modern Fuel Systems – Prevent fuel vapors from entering the atmosphere – Store and pump fuel – Filter the fuel – Deliver the fuel to the injectors

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Typical Fuel Delivery System

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Basic Fuel System Diagnosis Insufficient fuel delivery causes lean mixtures Excessive fuel delivery causes rich mixtures No fuel delivery causes a no-start condition Fuel system components can be grouped: – Fuel delivery – Fuel injection

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Contaminated Fuel Water in fuel can causes driveability concerns Over time fuel becomes less volatile or stale When stored a long time, fuel breaks down into carbon and gum If fuel smells sour it is stale

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Contaminated Fuel (Cont.) Check for E85 in fuel Customers can mistakenly fill with E85 Customers may fill with E85 because of lower cost

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Guidelines for Safely Working on Fuel Systems Release system pressure before disconnecting any fuel lines or fittings Always wear eye protection and follow all other applicable safety rules Disconnect the negative battery cable when working with fuel under the hood

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Guidelines for Safely Working on Fuel Systems (Cont.) Remove fuel filler cap slowly if venting vapor Do not smoke when working near any fuel- related component Do not allow heat or flames to be near while working on the fuel system Remove electronic devices from your clothing

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Fuel Line Warning Tag

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Handle and store all fuels with caution Clean up all fuel spills immediately Replace any damaged fuel line Make sure mating parts are clean when reinstalling fuel lines Plug disconnected fuel lines Use proper fuel line tools for connections Guidelines for Safely Working on Fuel Systems (Cont.)

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Knowledge Check Technician A says to relieve fuel system pressure before opening a fuel line. Technician B says use only the proper tools for disconnecting fuel lines. Who is correct?

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Fuel Tanks Allow for vapor containment, expansion, contractions, and overflow About 10% of tank volume is used for expansion in hot weather Constructed of steel, aluminum, or plastic Baffles reduce sloshing

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.

Fuel Tank Sending Unit Most contain the fuel pump and gauge sending unit The strainer or sock stops dirt or rust from entering the fuel pump

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Leaks Road damage Corrosion or rust Loose, damaged, or defective seams Loose mounting bolts Damaged mounting straps Fuel Tank Inspection

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. The fuel tank must be drained before removal Remove negative battery cable Use appropriate fuel storage container Fuel Tank Draining

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Always follow the manufacturer’s procedure Relieve the fuel pressure before disconnecting any lines or fittings Clean dirt from around fittings before removal Never use heat around fuel system components Fuel Tank Service

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Fuel Tank Removal - Typical Disconnect battery negative cable Relieve fuel system pressure and drain tank Raise and support vehicle Clean dirt away from lines and fittings Disconnect fuel tank wiring harness and ground if used Disconnect fuel lines from the tank

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.

Fuel Tank Removal (Cont.) Clean and disconnect filler pipe connections Remove filler hoses from tank Loosen tank strap bolts Ensure all wires and hoses are unhooked Remove tank strap bolts and slowly lower the tank to the ground

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Filler Caps Are non-venting and have some type of pressure-vacuum relief valve Designed to prevent over tightening Replacement caps must fit exactly as the original

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.

OBD II Monitor Enhanced systems have vacuum-based EVAP system Detects a loose or missing filler cap May display a “check gas cap” message

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Fuel Cap Testing Should be checked if PCM detects an EVAP system leak May be checked as part of emissions testing Special tester is needed

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Capless Fuel System Ford design uses a spring loaded flapper valve Seals tightly until fuel nozzle is inserted When removed, the valve is shut by springs Reduces vapor loss during filling fuel tank

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Capless Fuel Filler

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Knowledge Check Technician A says a loose gas cap can cause the “check engine” light to turn on. Technician B says a faulty gas cap can turn on the “check engine” light. Who is correct?

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Fuel Lines and Fittings Can be metal tubing, flexible nylon, or synthetic rubber hose specific for fuel use Many tanks have vent hoses to allow air in the tank to escape during fueling Sections of line are assembled with fittings May be threaded or quick-release Lines may be clamped

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.

Inspection All lines should be inspected for holes, cracks, leaks, kinks, or dents Rubber lines should be inspected for leaks, cracks, cuts, kinks, oil soaking, and soft spots or deterioration Inspect steel lines for rust Inspect nylon lines for cuts, kinks, or melting

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Line Replacement Replace with line of similar construction Always use new clamps Use a tubing bender to prevent kinks Nylon lines have some flexibility but cannot be bent sharply Be careful not to scratch or nick nylon line Tighten threaded fittings to specifications

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Fuel Filters Most vehicles have an in-tank strainer and a fuel filter Many filters contain a pleated paper element The inlet and outlet are usually marked Most filters are metal cased though some are plastic

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. In-Tank and Inline Filters

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Servicing Filters Always replace at specified intervals Restricted or plug filters can cause low fuel pressure and reduced volume Clean the filter connections before removal Ensure replacement filter is correct Replace filter and fitting components as needed

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Fuel Pumps Pumps draw fuel from the tank and pushes it to fuel injectors Electric pumps can be inside or outside of the fuel tank Some vehicles use two fuel pumps In-tank pumps kept cool by the fuel

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Diaphragm Plunger Bellows Impeller or rotary – Most in-tank pumps are rotary pumps Fuel Pump Designs

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.

Diesel Engines All diesel engines use fuel injection Older models use a fuel distributor New models use common rail or direct injection The electric fuel pump delivers fuel to the engine Pressure may be boosted to pressures up to 26,000 psi

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Fuel Pump Circuits

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Fuel Pump Circuits (Cont.) Fuel pump runs for two seconds KOEO The PCM shuts off the fuel pump when: – Long, high speed, closed throttle coast down – When engine speed exceeds a predetermined limit – When the vehicle speed exceeds the speed rating of the tires

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Rollover Protection Inertia switches shut off the fuel pump circuit in the event of rollover or collision The switch can be reset after being tripped Most passive restraint systems signal the PCM when an air bag is deployed The PCM then turns off the fuel pump circuit

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.

Knowledge Check A vehicle has zero fuel pressure. Technician A says the inertia switch may be open. Technician B says the inertia switch may be shorted. Who is correct?

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Returnless Systems Many modern vehicles use returnless systems Fuel pressure regulator is mounted in the tank The PCM uses PWM to control pump output A fuel pressure sensor is often located on the fuel rail

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Troubleshooting Inspect for leaks Test fuel pressure KOEO and/or KOER as specified Excessive pressure can cause a rich condition Insufficient pressure can cause a lean condition

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.

Common Causes of Higher Than Normal Fuel Pressure Faulty Pressure Regulator Obstructed Return Line – Disconnect the fuel return line at fuel tank and retest – If still too high, disconnect return line at regulator and retest

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Common Causes of Lower Than Normal Fuel Pressure Clogged filter Restricted line Weak pump Leaky pump check valve Faulty regulator Dirty filter sock

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Residual Pressure Poor starting can be a result of a lack of residual pressure Check pressure after engine has run and then turned off Pressure should hold for about five minutes

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Fuel Volume Test Test according to service procedures Conducted by collecting fuel dispensed in a certain time period, normally 30 seconds Disconnect the return line and place into a graduated container Run fuel pump for 30 seconds Should pump about one pint (0.47 liters)

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Fuel Volume Testing Connect fuel pressure tester to test port Place bleed hose into a suitable container Command fuel pump operation for 30 seconds Measure fuel volume

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Using a Lab Scope

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Using a DMM Used with a pressure transducer to measure fuel pressure Can also monitor current flow Excessive current means slower armature rotation Low current can be caused by excessive resistance

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. No-Start Diagnosis Check the fuel gauge Check for fuel in the tank Listen for pump noise If pump is not running: – Check for voltage at pump – Check the pump relay

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part. Replacement Ensure replacement pump meets or exceeds pressure and volume requirements Disconnect battery negative cable first Observe correct polarity of connections

© 2015 Cengage Learning. All Rights Reserved. May not be scanned, copied, duplicated, or posted to a publicly accessible website, in whole or in part.