Engine Works & Wears Engine Wear Combustion Process Internal Components External Components Cooling System Lubrication System Fuel System Air System Electronics

Single Fuel System

Function of Fuel System

Meters the amount of fuel to achieve desired power

Regulates engine speed and timing sequence

Helps control emissions

Fuel System Operation

Pump & Line Current Scroll Fuel System New Scroll Fuel System Sleeve Metering Fuel System (SMFS) Program Electronic Engine Controls (PEEC)

Timeline

1988EUI

1974 SMFS

1975 1980 1985 1990 1995 2000 2005Pre 1970 1970

1994HEUI

1987PEEC

1981MUI

2004 Rail

Types of Fuel Systems Unit Injection

MUI EUI HEUI Common

Rail(Single Fuel)1983

NSFS1973CSFS

Fuel Delivery - History Pre-Combustion (PC) Direct Injection (DI)

Pre-Combustion Direct Injection Pencil Style

Direct Injection Unit Injector

Fuel Line

Fuel Injector

Glow Plug

Heat Plug Piston

Electrical Wire

Fuel Injector Housing

Pre-Combustion

Fuel Line

Fuel Injector

Piston

Nozzle Assembly

Mechanically Controlled Unit Injector

Filling Begin Injection

Continue Injection

End Injection

Barrel

Plunger

Sleeve

Fill Port

Spill Port

Sleeve Metering Fuel System

Scroll Metering Fuel System

Pump & line governor Few moving parts Simple mechanical governor Easy starting & service More tolerant of dirt Economical

A unit injector is positioned above each cylinder

A mechanically actuated governor controls fuel rate (scroll metered) with flyweights and springs

Timing is fixed

MUI System

A unit injector is positioned above each cylinder

An Electronic Control Module (ECM) controls fuel rate and timing

Injectors are mechanically actuated by a camshaft

EUI System

EUI - Injector Fill

Without pressure from the rocker arm, a spring keeps the plunger retracted

Fuel flows into the injector through the fill / spill port, past the solenoid valve and into the barrel

EUI - Injection On a signal from the

ECM, the solenoid closes the fuel valve

Pressure elevates at the tip to the 5,500 psi needed to unseat the valve

Injection begins

EUI - Injection Fuel continues to inject until the ECM signals the solenoid to open the valve

Injection timing and duration is controlled by the ECM

A unit injector is positioned above each cylinder

An Electronic Control Module (ECM) controls fuel rate, timing, and injection pressure

The injector is hydraulically actuated

HEUI System

Cat Fuel System – Single Fuel

C6.6

Fuel Manifold

Pump

Injector

Fuel System Wear & Failure Causes Short unit injector life due to excessive abrasive particles in

the fuel Abrasive particles damage sealing surfaces causing leakage of

high pressure fuel and low engine power Abrasive particles are inherent in most fuels Most particles can be removed by using High Efficiency filters

Injector seizure due to excess water in the fuel Always small amounts of water in fuel, which is harmless Excess water in fuel reduces the lubricating film strength of fuel

and causes seizure of the injector plunger and barrel Maximum amount of allowable water in fuel is 0.1%

Fuel System Wear & Failure Causes Injector sticking or seizure due to fuel overheating

Fuel in the injector “cooks” and produces varnish which causes components to stick or seize

Viscosity of hot fuel is inadequate and the fuel film thickness will not provide adequate protection against scuffing or seizure of the plunger and barrel

Fuel overheating can be caused by operating in extreme ambient temperatures. An auxiliary fuel cooler installed in the fuel supply line to the cylinder heads may be required to limit fuel temperatures

Running fuel tank too low, or running out of fuel causes the fuel to cycle through the engine too frequently and becomes very hot. This can be avoided by keeping the fuel tank levels at ¼ full or above

Fuel System Wear & Failure Causes Poor quality oil

Fuel may be low in viscosity or lubricity. Fuel which is old or oxidized often contains excessive gums or resins which promotes injector sticking or seizure.

Effect of Work Environment Dust Temperature/Climate Hours of continuous operation Terrain

System Improvement

Reduce system damage caused by fuel Water Separator Primary Fuel Filter Bypass Flow

Minimize tip failure caused by aeration Maintain fuel supply pressure

Stripping Out Water

Water Separator Second line of defense

All free water 87% emulsified water

Injector damage

Removing Larger Debris

Primary Fuel Filter 10+ micron particle retention

prevents premature secondary fuel filter plugging

protects fuel transfer pump

Remove Fine Abrasives

Secondary Fuel Filter 2 micron and larger

98% efficient Reduces wear on fuel injectors and pumps

Essential for higher pressure systems Extends life of older systems as well

Double Filter/Double Life

Series filtration Second filter “safety net”

Second filtering pass Filter failure

- Double injector wear life

Engine Works & Wears Engine Wear Combustion Process Internal Components External Components Cooling System Lubrication System Fuel System Air System Electronics

Air Intake & Exhaust System Functions

Compresses the intake air into the cylinders in order to product more power Removes exhaust gases from the

cylinders and reduces exhaust noise

Provide adequate quantities of clean filtered intake air

Inlet air from air cleaners

Exhaust out

Boost air at 300 º- 400º

Air manifold

Inlet air from air cleaners

From exhaust ports at cylinder heads

Air System

Precleaner Air Filters Filter Service

Indicator Turbochargers Aftercooler Intake & Exhaust

Manifolds Muffler

Air System Components

Air System Operation Flow

1. Precleaner2. Air Filters3. Turbocharger4. Intake Manifold &

Cylinder Head(s)5. Combustion

Chamber6. Exhaust Manifold

Wear Turbocharger

Bearings Seals

Air System Wear & Failure Causes

Single most common problem – dust ingestion Causes accelerated abrasive wear of piston rings & liners Most often caused by inlet leaks around flexible joints in

air inlet piping May also be caused by defective/damaged air filters, or

poor maintenance practices

Plugged air filters Turbo failures Coolant to air leaks in the aftercooler Hydraulic lock