January 2013

Technical Diesel Information for the Garage Engineer

Poor Starting Common Rail

Engine?

The winter freeze is coming can a diesel fuel additive help?

In this issue

● Part One of

Understanding the

common rail injection

system.

Page 4

● Diagnosing high back

leak on common rail

injectors.

Page 5

● Stop your customers

diesel fuel waxing this

winter.

Page 6

01233 642816

Thomas Auto Injection Centre Ltd

Welcome to the Thomas Auto Injection Centre ‘Diesel tech talk’ online magazine.

The aim is to assist yourself and staff by giving out free information and tips about the diesel

fuel vehicle.

Feel free to download the magazine and pass it on to other engineers if you find the subjects

useful.

If there is a particular diesel injection system subject you would like us to cover please email

to graham@thomasautos.co.uk

Company history

Formed in 1977 in a Kent farmyard as J.A. Thomas Fuel Injection Engineers, Thomas Auto

Injection Centre Ltd has become known worldwide for its technical expertise and parts sales.

The company is now located at 93 Ellingham Industrial Estate Ashford, Kent TN23 6LZ with

good links to both the UK and the Continent.

After many years in the fuel injection business we are finding the new technologies both a

challenge and exciting.

We will continue to invest believing that all repair work should be done “in-house”.

Our parts sales business has been a natural progression and utilises our technical expertise.

New manufacturers added to our range include Mr Funnel and Racor.

Over the past decade Thomas Auto's customer base has grown from local businesses to

companies worldwide.

In 1995 we became Stanadyne Central Distributors for the UK. Since then we have become

responsible for the Republic of Ireland, Kenya and Nigeria.

At the beginning of 2004 a new and exciting challenge began with a change of ownership.

Three employees who intend to give the company the energy and enthusiasm required to move

forwards have purchased the company.

Since then a new large parts stores has been built to handle the increased bulk filter and fuel

additive requirements, a new top of the range Bosch test bench has been installed, Yanmar has

officially instated us as the only Yanmar fuel injection pump workshop in the UK, a MOT bay

has been added and the work force continues to grow.

Our philosophy is simple, the best training, genuine parts, good value and excellent service.

Directors: Kathy, Neil and Richard

Phone: 01233 642816

Website

www.thomasautos.co.uk

Internet Shop

www.dieselpartsdirect.co.uk

The Common Rail Diesel Injection System. Part 1

Introduction:

Common Rail is a fundamental change in diesel technology and it is

happening now.

The modern direct-injection engine is a pre-requisite for new diesel-

powered passenger vehicles across Europe.

It is the only technology to address all planned European emissions

legislation, whilst enhancing reliability, performance & fuel economy.

The number of diesel cars we see on our roads is constantly growing. In Europe alone, this

growth is predicted to continue at an average rate of 10% per annum, with common rail

systems growing by more than 35% per year.

Safety:

With the fuel pressure capable of running at >1600 bar and at >70 degrees Celsius safe

practices must be followed.

Injected fuel can enter the bloodstream . If oil has penetrated the skin, seek medical help

immediately. Hospital treatment is imperative and urgent.

Never test for leaks with the engine running or without letting the pressure dissipate once

keyed off. If live pressure data is not available wait a minimum of 15 minutes before

releasing any pipe or connection fittings.

Never release a injector or feed pipe nut with the engine running whilst looking to see if an

injector is receiving fuel.

Never use your finger or any body parts to find a leak.

Cleanliness is next to Godliness:

Clean area before disassembly.

Never use a air line to clean area.

Use a vacuum cleaner to remove debris.

Place all removed parts in a clean plastic container.

Cap all open ports immediately.

Refitting requires same care.

Correct diagnosis of a suspected fault can only be accurate if these

are carried out.

Common Rail Facts: Fuel droplets measure only 20 microns diameter.

Fuel exits the nozzle at up to 1240 mph.

Injection takes place in 1-2 milliseconds – That's 200 injections for a single

blink of the eye lid.

Production allows variations of just 0.2microns for any moving parts, in comparison a

human hair is 30 times thicker.

Latest versions can fire fuel 7 times per firing cycle.

Fuel pressures now up to 2200bar / 31908psi

The low pressure supply.

Fuel from the fuel tank is pumped via a low pressure pump or vacuumed from a low pressure

pump situated on the high pressure pump. The fuel passes through a fuel filter and into the

high pressure pump at a minimum of 0.8 bar or the system will shut down.

This minimum pressure is to insure that the high pressure pump is lubricated. Normal running

supply pressure will be in the 2-3 bar range.

High Pressure supply

The fuel amount is controlled by the Inlet fuel metering valve (suction control valve on Asian

vehicles) The fuel is pressurised by the high pressure pump elements and fed to the common

rail. The rail is used as a storage unit to remove pulsing from the fuel when the injector opens.

From the rail pipes direct the fuel to the injectors.

The injectors opening is controlled by the vehicles onboard computer using sensors around the

engine to determine the correct amount of fuel to be injected and the timing of the injection in

relation to the piston position.

The injector using fast electronic solenoids or piezo stacks can fire multiple times. The injector

will be covered more deeply in later issues of “Diesel tech talk”

Leak back return

A controlled amount of fuel is not used by the injector for injection but is used for injector

Lubrication. This amount due to de-coupling from the high pressure is returned to the filter/

tank under low pressure normally via rubber or plastic tubing.

Rail pressure on some applications can also be regulated via a control valve. This along with

un-pressurised from the IMV is also returned at low pressure.

Some early systems also had a fuel cooler on the return.

Next Issue we look in depth at the High pressure pump

Poor or non starting? We have many vehicles equipped with the common rail injection system brought into the

workshop. A high percentage of them suffering with difficult or non starting.

First check should be a ECU diagnostic check with your scanner looking for

fault codes.

If you extract codes relating to “Low or incorrect fuel pressure” or “Inlet

metering valve faulty” your next test needs to be a live data look at the fuel

pressure at idle and on cranking.

At cold temperatures expect to see between 320 to 340 bar at idle speed. If

the engine is warm the pressure will vary from260 to 280 bar.

If your vehicle will not start look for a fast pressure build up over only a few

cranking revolutions with a pressure of 250bar or in excess easily obtained.

If you have none or extremely low pressure <50 bar then the high/low pres-

sure pump or supply may be at fault, but a back leak check should still be

performed encase all injectors have high back leak.

If the vehicle will start also look at the fuel pressure to see if it varies within

10 bar. If the variation is far greater and or the pressure on cranking is far lower than the above

reading further investigation to the condition of the injector back leak amount is required.

Testing the injector back leak

With engine switched off unclip the back leak connector pipes and seal with clean plugs.

Clip on the test container pipes, hang container bottles away from rotating parts and start

engine and allow to idle.

On this example number 2 cylinder is showing a high back leak. This injector requires

replacing and on this example a Ford Mondeo the injector will need re coding to the ECU for

it’s fuelling characteristics. We will “tech talk” recoding in the next issue.

Cylinder #2 back leak incorrect—To high.

YDT278 Sealed rail testing kit

The Sealed Rail Kit provides simple, low-cost

diagnostic capability for pumps and injectors on

Common Rail systems made by all major manu-

facturers.

Features & Benefits

• Identifies faulty component (pump, injector)

within Common Rail system

• On-vehicle testing – prevents need for complete

system removal and refit

• Measures pressure generated by Common Rail

pump

• Measures back leakage for each individual

injector

• Compatible with Delphi, Bosch, Siemens &

Denso systems

• Contains adapters needed for tests on all-makes

applications

• Reduces costs and inconvenience for end

customer

Call Tony on 01233 642816

for details and cost

The winter freeze is here

can a Diesel Additive help?

Stanadyne performance formula

reduces diesel waxing by up to 22

degrees Celsius

The premium all-season, multi-function diesel fuel additive, designed to tackle virtually

any diesel fuel related problem.

Meets all fuel system requirements regardless of make, model or year

Approved by Original Equipment Manufacturers (OEMs)

Cold Weather Protection - reduces diesel pour point up to 40°F (22°C), and cold filter plug point

by up to 25°F (13°C), depending on base fuel

Hot Weather Protection - lubricants and cetane improver help when fuel is hot and "thin"

Increases Horsepower - with up to 5 point cetane gain to improve combustion, resulting in better

acceleration, power and torque

Reduces Fuel Consumption - independent tests show gains up to 9.6% in MPG

Easier and Faster Starting - in all conditions

Reduces Smoke and Particulate Emissions - and is suitable for ultra low sulphur diesel

Cleans and Protects - detergents and deposit modifiers help protect injection pumps, injectors,

nozzles, etc.

Reduces Wear - lubricity improvers restore lubricity to ultra low sulphur and other low lubricity

diesel fuels

Stabilizes Fuel - antioxidants keep fuel fresher

Fights the formation of corrosion and rust

Contains No Alcohol - avoids corrosion and accelerated wear

Performance Formula®

38564F

1 Shot

Treats 120 litres

Only

£5

38565F

470 litre

Treats 235 litres

Only

£9.23

38566F

1.9 litre

Treats 950 litres

Only

£32.11

Call Tina now on 01233 642816 to order whilst stocks last (inc vat)

www.dieselpartsdirect.co.uk

Last year we were dealing with up to five call outs each day due to “waxed” diesel fuel from the cold.

Next Issue

Part Two of The Common Rail Injection System

Stopping the Diesel Bug”

Water problems & how to solve them

Technical Diesel Information for the Garage Engineer

Free with compliments from

Thomas Auto Injection Centre

93 Ellingham Industrial Estate, Ashford, Kent TN23 6LZ

01233 642816