Low diesel fuel pressure, what is really the problem?

Emission standards for diesel engines are getting stricter every year in Europe.

And Europe is the second largest market in the world for diesel fuel injectors.

You will have heard of euro 2 and euro 3 and so on;  these are the standards set by the European Commission for fuel exhaust levels.

Diesel fuel emissions are in the news at present and there is always pressure on the manufacturers to improve the emissions.  

Diesel and petrol fuel injectors are complicated parts in a modern engine.

The spray holes in the end of a modern common rail diesel fuel injector are sometimes only 50 microns in diameter

To give  a clearer idea of this size the human hair is around 100 microns in diameter!

This gives us a clearer idea of the very fine tolerances in a modern diesel fuel injector. Problems can arise when dirt is drawn from other parts of the engine like the fuel tank .

Modern diesel engines work at very high pressures so any dirt can cause a reduction in performance.

A common problem is low fuel pressure.  Sometimes when there is low fuel pressure the injectors need to be changed but there are times when the injectors are not the problem –  the problem is elsewhere in the system.

It could be,  for example,  that the pump is not producing enough pressure.  It could be a fuel metering valve problem or it could be contamination in the fuel rail.

Of course this does not exhaust all the possible causes of the low fuel pressure problem.

Fitting new injectors may not solve the underlying problem and  if the problem is still there it could result in new injectors failing early

A spokesman for Delphi diesel components has said garages must also play a part in ensuring injectors and pumps are not damaged or contaminated during the fitting process.

He continues the areas where such components as pumps and injectors are stored and worked on needs to be clean and torque settings must be adhered to.

Also care must be taken after all especially in the case of diesel the fuel system is a high pressure system

A certain percentage of the items returned to reconditioning companies are returned because they are contaminated or have not been fitted properly – there is no fault with the unit!

Another problem is when injectors are not programmed properly

Other problems can include the fuel pump itself although the fuel pump should last for a long time if the vehicle is properly serviced and maintained.

Typical causes for low fuel pressure are dirty fuel filters and  incorrect tank venting.  

This happens when the vent in the fuel tank becomes blocked or partially blocked and does not allow enough air in to replace the fuel that is being drawn off

Unfortunately diesel fuel does have dirt in it these deposits to build up on the fuel injectors This results in an alteration of the spray pattern and the amount of fuel being injected becomes less efficient.

Over the moon!

“Over the moon with this part as Audi wanted over £600 for a fuel injection pump”John W

Yes! John W (one of our customers) saved a pile of money by changing just the fuel pump pressure regulator.

So I am writing this blog to help clear up some of the myths about these regulators and sensors

This blog is about fuel pressure sensors and fuel pressure regulators

These small electronic components that are part of the control system in a modern car. Just to be clear Fuel pressure regulating valves are sometimes called fuel regulating valve or fuel pump regulating valves.

fuel pressure sensor and common rail
Fuel pressure sensor in common rail
Urban myth: you can’t just change the fuel pump regulator you have to fit a new fuel pump.

True or false: If the fuel pump regulating valve is faulty you have to change the whole pump you can’t just change the regulator valve.

False! if it is just a fuel pressure regulating valve problem then simply fit a new regulator.

A new fuel regulator valve will cost you around £130 or less and can be fitted in around 30 minutes.

A new fuel pump may cost you over £600 and will take a number of hours to fit.
fuel pressure regulator valve and pump

Urban myth: fuel pressure sensors are only sold as a set with the fuel rail included brackets common rail close brackets

True or false: Fuel pressure sensors are not sold separately you have to but the fuel rail as well

False! We sell a wide range of fuel pressure sensors and fuel regulating valves.

The common rail fuel tube is a heavy duty tube – it has to be to deal with pressures up to 2000 bar normally it is not subject to any wear – so put simply there is no need to buy it and no need to change it!

We stock Bosch Delphi Siemens and Denso fuel regulating valves and fuel pressure sensors

Fitting a new fuel pressure sensor: simply unplug the wiring loom from the sensor and unscrew the faulty sensor

Fit the new sensor and refit the plug – job done.

London Mayor wants diesel scrappage scheme

How can we improve air quality in our cities?

The Mayor of London Sadiq Khan has called on the government to introduce a national diesel scrappage scheme .

The aim of the scrappage scheme is to scrap older diesel cars when the owner buys a new vehicle

The government is trying to encourage people to get rid of older diesel vehicles and buy electric and hybrid vehicles.

Of course the scrappage scheme is controversial; not everybody agrees with it

What are the environmental advantages of scrapping lots of vehicles which are probably still in good condition.  They can be repaired and will the scrappage scheme mainly mean that the vehicle manufacturers can sell lots of new vehicles?

Making new cars has an environmental cost and, of course it means jobs for workers in the car industry and profits for the Motor Manufactureres

Sadiq Khan is the Mayor of London and he is blaming diesel cars, he is blaming older diesel cars for air pollution and poor air quality.

Some people say that buses and taxis are big contributors to diesel pollution of the air and some people are very unhappy that diesel cars are being targeted.  
They say that a few years ago the government was encouraging people to buy diesel.
Now  all of a sudden things are different and certain people feel let down

 Sadiq Khan is not happy with the levels of nitrogen oxide in the air. He says that  the levels are too high and he also said that he would not rule out banning diesel vehicles from London all together if the air quality does not improve.

Some people argue that it is not just cars that cause pollution – they talk about aeroplanes,  farm tractors and other kinds of machinery.

Some people when talking about the traffic problems in London point to  black cabs and buses.  
All these are running on diesel engines and what happens about uber cabs?
They are diesel but there are not so many controls on them.

The Guardian newspaper recently printed an interview with Sadiq Khan he said
“The toxic state of our air leaves us with no choice but to rid our city of the most polluting diesel vehicles. It is shocking that nearly half of new car sales in the UK are still diesel vehicles and the tax system still incentivises motorist to buy these polluting cars”

Some people do not like the diesel scrappage scheme;  they think that it will mainly benefit the vehicle manufacturers and simply help them to sell more cars.  Also the older vehicles which are being scrapped mean that fewer economically priced cars will be available for people with less money to spend.

Diesel fuel – Fossil or Bio, Green or dirty?

Should you use diesel with added bio fuel or should you avoid it?

Do you buy your fuel from supermarket outlets or do you insist on buying fuel from an independent supplier?
Do you know how much biofuel has been added to the fuel you put in your vehicle?

A lot has been written about diesel but diesel fuel quality is a question that still remains.

To begin: there’s fossil fuel and there’s biofuel.

Fossil fuel is pumped out of the ground and then cleaned and refined. Biofuel is manufactured using plant material of different types.

Biofuel:  is it good for your engine?

The government and some environmental groups want to increase the amount of biofuel added to the mix. This might be good for the environment and it might be good politically but engineers remain to be convinced that plant oil can be mixed in with fossil oil without harming the engine.

Steven Smith is managing director of Feather diesel he says “Biofuel is more unstable and tends to degrade progressively”

He went on to say oxidisation creates formic and acetic acid, which attack  the fuel injection equipment.

The problem seems to be that to refine biodiesel you have to use a certain types of chemicals and these in themselves can cause problems.  In addition to this biofuels attract free water that is in the atmosphere and water is the enemy of common rail diesel.

Supermarket fuel is it good or is it bad?

Many people have raised a question mark about supermarket fuel.

The fuel firms that supply supermarkets do add different ingredients to the fuel but it’s difficult to find out what these additives are as they are closely guarded secrets.

The big diesel fuel injection manufacturers Bosch Delphi Denso and Siemens VDO have issued a common statement. They agree that diesel which includes 7% biodiesel should be the maximum – they’re not happy with anything higher than that.  

Modern common rail diesel engines have a lot of advantages over the old conventional diesels.   

Quieter and smoother

They are quieter,  they are smoother and a great deal more fuel efficient and less polluting,  but to achieve all this they work on  much closer tolerances.

Because of this higher level of precision good servicing is absolutely essential.

This means regular oil changing as well as fitting OEM quality filters. Some of these filter down to a level of less than 10 microns.  And trying to ensure that the fuel you are using is good quality resulting in good lubrication for pump and injectors and other components in the diesel system.