How to prolong diesel injection pump life

How to prolong Diesel Injection Pump Life

Despite the bad press, modern, high-pressure injection diesel engines are technological marvels. Their outputs are impressive, they are hugely fuel-efficient and, yes, even when we try to forget the ‘Diesel Gate’ and car manufacturers’/governments’ skulduggery, the overall exhaust emissions are remarkably low.

What does a diesel injection pump do?

Most modern diesel engines require two fuel pumps. A relatively inexpensive electrical low-pressure one lies within the fuel tank. This is powered electrically using a dedicated fuel pump relay. It delivers fuel to the high-pressure fuel pump, driven mechanically by the engine, which is this article's focus.

The high-pressure unit pressurises the diesel fuel to around 2,000PSI (for context, a typical car tyre is inflated to 30PSI), which permits the fuel injectors to pulse fuel into the engine with the utmost accuracy.

For this reason, modern high-pressure diesel fuel pumps, as well as the fuel injectors, are precision-made parts allowing you to check if diesel pump is working.

How do I know if my high pressure diesel pump is faulty?

Bad diesel fuel pump pressure, either high or low pressure, will prevent the diesel engine from restarting. You may also find an illuminated dashboard malfunction indicator lamp that points to a low fuel pressure fault code. Poor running can also result, especially under hard acceleration.

However, low fuel pressure can be caused by other factors. Ensure an accurate diagnosis. The fault could lie with cheaper parts of the system, such as electrical sensors. Engaging a specialist to test the system with dedicated equipment is a good start. Therefore, be wary if you are told that the pump is faulty, without other causes being investigated first. If the pump is kaput, consider that high-quality re-manufactured/reconditioned items tend to be cost-effective alternatives to new parts.

What is the average cost of diesel pump repair?

Much depends on the make and model of car, the nature of the fault and even the area in which you live. Low-pressure pump failures tend to be relatively inexpensive to rectify. High-pressure pumps are far more complicated. A new replacement can cost over £2,000 and significant dismantling tends to be required to replace it. This is why we recommend that cheaper options are examined first, before the high-pressure pump is condemned.

Tips to prevent common diesel pump failures

To ensure optimum life from your diesel engine fuel injection pump, avoid these situations:

1. Running out of fuel:

Diesel lubricates the pump. When the fuel tank runs dry, air replaces the diesel. This promotes rapid wear within the pump. A low fuel level causes other problems, too, as this related blog explains: https://www.motoringassist.com/news/avoid-running-on-reserve

2. Misfuelling:

Should you fill up with petrol accidentally, the fuel injection system can be damaged before the engine is even started. This is because petrol possesses zero lubricating qualities for diesel fuel pumps. Do not even turn on the ignition; seek advice and organise transportation, so that the fuel system can be drained and flushed professionally.

3. Poor quality fuel:

Fuel contamination is a top cause of diesel fuel injection pump failure. Therefore, avoid filling up your car with bad diesel fuel from a drum. If you use a fuel can, ensure that the diesel has been filtered and that you know its source. Apart from being illegal, unless duty has been paid on it, never use other fuels in your modern diesel car. This includes pure bio-diesel, unless you are buying it from a credible supplier that warrants that the fuel will not damage the delicate high-pressure pump.

4. Neglected maintenance:

Diesel fuel filter housings require annual water drainage. Regardless of manufacturers saying that they can be left for longer, replace the fuel filter cartridge annually. Use good-quality filters, because poor-quality substitutes tend to fall apart and the resultant fragments damage the pump.

5. Inadequate bleeding:

Certain diesel pumps can be damaged severely by incorrect, or insufficient bleeding, which is when air is purged from the system and replaced with diesel. Bleeding is needed either after an empty fuel tank has been replenished, or after the fuel injection system has been repaired, or maintained.

Some vehicles require diagnostic equipment so that they can be bled correctly.

6. Performance modifications:

Some engine tuning modifications raise pump pressures and cause internal overheating, which can shorten its life. Also, certain cetane-boosting diesel fuel additives affect the diesel fuel's lubricating quality, which increases internal pump wear if not dosed correctly.

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