Time For Your Injection!

              FAULT FINDING ON EARLIER DIESEL SYSTEMS

This information covers diesel systems without electronic diesel control, so this relates to most car and light commercials from 1960-1985. This information is a good source for locating any running fault you may have. The single largest cause of problems on early diesel systems is not poor fuel as you would expect, rather it is air, yes air in the fuel lines. This will cause all sorts of havoc with your engines performane so don't under estimate this. Although this is not extensive as there are so many different systems in operation, however I have been using these methods since 1972 and rectified problems on literally thousands of vehicles, it works!  Scroll further down the page you will find details on fault finding on common rail systems too.

Kind regards
Diesel Doctor

Black Smoke

Heavily carboned inlet/exhaust valves (Pressure & heat escaping past the valve seat) Compression test will not pick up this problem, you must have a cylinder leakage test carried out on the engine.

Injectors Hosing

Insufficient air, remove the air intake filter, does the exhaust run any cleaner.

If you have an EGR system remove the intake manifold and investigate for carbon build up around the cylinder heads intake ports.

Overfueling Injection pump.

White Smoke

Injection timing running retarded, check pump to engine timing marks.

Air in the fuel system. Install clear pipe from Injection pump to filter and observe for air in the fuel. Alternatively connect pipe from pump inlet to container of fuel (by-passing the rest of the system). If the engine runs OK, then investigate fuel supply from filter to tank.

Blocked fuel filter 

Blocked feed and return bolts.

Blue Smoke

Engine is burning oil, remove oil filler cap, crank engine, is the engine breathing heavily.

If in doubt carry out a compression test, rule of thumb 300-350 p.s.i most importantly uniformity across cylinders. 

Check fuel filter, is there any black oil residue on the filter, if the answer is yes the most likely source for this will be defective lift pump (if fitted). Defective fuel pump drive seal (if pump is gear/chain driven)

Engine Difficult To Start

Glow plugs

Air in the fuel system. Install clear pipe from Injection pump to filter and observe for air in the fuel. Alternatively connect pipe from pump inlet to container of fuel (by-passing the rest of the system). If the engine runs OK, then investigate fuel supply from filter to tank.

Injector nozzle needle stuck in open position

Lift pump failure (where fitted)

Injection pump

Engine will not switch off

Remove electrical connection to stop solenoid, if the engine stops have the wiring checked.

Remove the stop solenoid, any debris stuck under the stop valve, check with a magnet, if these are metal particles, this could be a sign the pump is breaking up internally.

If the engine is breathing heavily (worn piston rings) it is possible the engine is running on vapour.

Engine stalls and will not start.

Empty fuel tank. I know this is obvious but often missed.

Air in the fuel system. Install clear pipe from Injection pump to filter and observe for air in the fuel. Alternatively connect pipe from pump inlet to container of fuel (by-passing the rest of the system). If the engine runs OK, then investigate fuel supply from filter to tank.

Check timing, has the belt jumped.

Fuel pump stop solenoid. Remove the solenoid assembly, hold the valve and spring inside the solenoid with your thumb, apply approx 12 volts to solenoid (must be earthed). Valve should move in. If faulty replace.

Pump Failure.

Engine Surge at Idle

Air in the fuel system. Install clear pipe from Injection pump to filter and observe for air in the fuel. Alternatively connect pipe from pump inlet to container of fuel (by-passing the rest of the system). If the engine runs OK, then investigate fuel supply from filter to tank.

Blocked return pipe

Blocked inlet or return banjo bolts.

Check adjustment of idle speed screw, also check adjustment of the anti-stall screw (If fitted)



Engine Misfire

Air in the fuel system. Install clear pipe from Injection pump to filter and observe for air in the fuel. Alternatively connect pipe from pump inlet to container of fuel (by-passing the rest of the system). If the engine runs OK, then investigate fuel supply from filter to tank.

Crossed feed and return pipes.

Blocked return pipe

Blocked inlet or return banjo bolts.

Injectors. If the misfire is noticeable at idle speed, place some rag or absorbant tissue aound one injector at a time, release the pipe nut at the Injector and listen for a tone change in the engine. If you can pinpoint the cylinder with the misfire, remove the Injector for testing or swap Injector with another from a 'good' cylinder and see if the problem moves. If the misfire is still evident on the original cylinder carry out a compression/cylinder leakage test.

SITE UNDER CONSTRUCTION

                  FAULT FINDING ON COMMON RAIL SYSTEMS

I would strongly recommend you have the vehicles ECU code read, this normally varies in price from £35-£50. This will be money well spent and save you hours of fruitless searching.  Below is a list of problems with possible causes, in the event that there is no fault stored in the ECU and a code read is not possible I suggest these items are checked. Please note this is for Common Rail Systems Only These systems do vary so information should be used for reference purposes only. 

SAFETY WARNING

Do not attempt to enter the fuel system until the engine has been stopped for a minimum of 5 minutes. Under no circumstances should high pressure pipes be released while the engine is running.

These systems operate upto and over 2,000bar pressure, these pressures will penetrate skin tissue and could be fatal.

Idle Problems speed & Exhaust emmisions
1.Air in system
2.Fuel filter
3.EGR
4.Air mass meter
5.Injectors
6.Rail pressure sensor
7.Pressure control valve
8.Fuel High pressure circuit
9.ECU
Does Not Accelerate
Throttle pedal sensor
High fuel Consumption
1.Fuel low pressure circuit
2.Air intake
2.Boost pressure control
4.Check vacuum system
5.Injectors
6.Compressions
7.Turbo charger
Max Revs not reached
1.Air intake
2.Fuel low pressure circuit
3.Fuel High pressure circuit
4.Throttle pedal sensor
5.Boost pressure sensor
6.Water temp sensor
7.Fuel Temp sensor
8.Rail pressure sensor
9.Injectors
Misfire
1.Supply pump
2.Engine
3.Fuel Quality
4.Air in fuel
5.Fuel filter
6.Water temp sensor
7.Injectors
Spontaneous acceleration
1.Throttle pedal sensor
2.Boost pressure sensor
3.High pressure circuit
4.Compressions
Engine will not start
1.Immobilizer
2.Main relay
3.Glow Plugs
4.Air intake system
5.Electric feed pump
6.Crank sensor
7.Fuel low pressure system
8.Fuel high pressure system
9.Pressure control valve
10.Water temp sensor
11.Rail pressure control valve
12.Rail pressure sensor
13.Injectors
14.ECU
Engine Cuts out and restarts
1.Fuel low pressure system
2.Fuel high pressure system
3.Pressure control valve
4.Injectors
5.ECU
Black smoke
1.Air mass meter
2.Air intake system
3.Water temp sensor
4.Leak in vacuum system
5.Boost pressure sensor
6.Turbo charger
7.Injectors
8.ECU
White/Blue smoke
1.Water temp sensor
2.Fuel low pressure circuit
3.Leak in vacuum system
4.Fuel filter
5.Injectors
6.Compressions
Rough engine running
1.EGR
2.Main relay
3.Crankshaft sensor
4.Fuel low pressure circuit
5.Fuel High pressure circuit
6.Leak in vacuum system
7.Electric supply pump
8.Water temp sensor
9.Fuel Temp sensor
10.Pressure control valve
11.Rail pressure sensor
12.Injectors
Bucking
1.Air in system
2.Main relay
3.Clutch switch
4.Stop lamp switch
4.Road speed sensor
Surge
1.Power supply
2.Clutch Pedal
3.Brake pedal
4.Road speed sensor
5.Leak in vacuum system
Cannot stop engine
1.ECU
2.Compressions

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paul | Reply 09.05.2020 21.26

hi could you send me the instructions for resealing the

LAND ROVER 300TDI bosch ve injection pump thanks Paul

ADS 10.05.2020 10.03

I could if you left your email address.
Contact me at diy.dieselshop@aol.com

ADS | Reply 01.05.2020 12.45

Thank you James. Do not hesitate to contact me if you need further assistance

James Moncrieff | Reply 01.05.2020 12.24

Excellent service, make sure that you include your email address when you message so that John can send you the instructions!

Dan | Reply 05.04.2018 20.25

For my test a question came up and ask, If return line is blocked what will happen to the diesel engine. It will be over pressurized. What will happen.

FREDFMILNE@AOL.CO.UK | Reply 19.04.2016 23.53

GETTING LOTS BLUE SMOKE AT LOW SPEEDS

Lynne | Reply 17.02.2016 12.24

Merc C220 sport. Automatic. In the morning starts first time then when putting transmission into reverse or drive the engine cuts out. Starts again with no prob

Ian | Reply 05.12.2015 04.24

Hi, Alfa Romeo GT, 113K miles. Intermittent surge in power when under load, became more persistant on long journey after excessive period of acceleration

Lucas Kmosola | Reply 18.11.2015 12.05

I have noted engine oil in my Massey Ferguson 398 diesel tank. The engine is releasing heavy white smoke and loses power. What my be the cause of these problems

ads 18.11.2015 12.37

Only two ways oil can get into fuel.
1. Lift pump
2. Injection pump drive.

Regards

See all comments

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I could if you left your email address.
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