How To Know It's Time To Replace Your Diesel Fuel Injectors

when to replace diesel fuel injectors

Diesel fuel injectors are responsible for turning fuel into tiny droplets that are easier for the engine to burn. When they fail, your car will run rough, accelerate slowly, and consume more fuel. There are several signs that indicate it's time to replace your diesel fuel injectors. These include a noticeable decrease in fuel efficiency, difficulty starting the engine, a persistent smell of fuel, and poor engine performance. While diesel fuel injectors typically last between 80,000 and 100,000 miles, they may need to be replaced earlier if any of these issues arise.

Characteristics Values
Average lifespan 80,000–100,000 miles
Signs of damage Lower fuel efficiency, difficulty starting, poor fuel economy, rough idling or low RPMs, engine vibration, engine misfires, engine not starting, foul smell from the engine or engine oil, increased engine emissions
Replacement cost $350–$850, with luxury vehicles costing up to $2,500

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Warning signs: rough idling, slow starts, engine vibration, check engine light

Warning signs that your diesel fuel injectors may need replacing include rough idling, slow starts, engine vibration, and the check engine light coming on.

Rough Idling

Rough idling is often what causes a car to vibrate. It indicates that the fuel and air provided to the engine are not mixing optimally. This can lead to poor performance, poor fuel economy, difficulty starting, and high or low RPMs. Rough idling can be caused by dirty fuel injectors, which become clogged by carbon deposits over time. This prevents the correct amount of fuel from being dispensed for combustion, resulting in poor performance and rough idling.

Slow Starts

If your vehicle is taking longer to start or is having trouble starting, especially when the tank is full, it could be a sign of a clogged or damaged injector.

Engine Vibration

Engine vibration can be caused by dirty or clogged fuel injectors, which interrupt the constant flow of fuel to the combustion chamber. This causes an uneven amount of fuel to be delivered with each engine cycle, resulting in the car vibrating or shaking while idling.

Check Engine Light

The check engine light coming on can indicate a range of issues, including problems with the fuel injectors. If the system fails and operates beyond predetermined parameters, the computer will produce a code that triggers the check engine light.

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Fuel injectors: lifespan, maintenance, replacement cost

Fuel injectors are responsible for pumping fuel through an electronically controlled opening that sprays the fuel into the cylinder, allowing the fuel to burn more efficiently and evenly. They are essential for your vehicle's engine performance and overall health.

Lifespan

Fuel injectors typically last between 50,000 to 100,000 miles in gasoline engines and 100,000 to 200,000 miles in diesel engines. However, their lifespan is not just determined by mileage or the type of vehicle but also by how well they are maintained. Regular maintenance, including cleaning every 25,000 to 30,000 miles, can greatly extend the life of fuel injectors.

Maintenance

To maintain fuel injectors, it is recommended to:

  • Use high-quality fuel that meets or exceeds manufacturer recommendations.
  • Regularly replace fuel filters (every 30,000 miles).
  • Conduct regular engine inspections to detect issues early.
  • Use additives designed for injector cleanliness to prevent the buildup of deposits.

Signs of Failing Fuel Injectors

It is important to be aware of the signs of failing fuel injectors to avoid larger engine problems. Some common symptoms include:

  • Lower fuel efficiency
  • Persistent smell of fuel
  • Difficulty starting the vehicle
  • Engine misfires and stalling
  • Lower RPMs

Replacement Cost

The cost of replacing fuel injectors can vary depending on the vehicle's year, make, and model, as well as the type and source of the replacement parts. For example, the cost of replacing all four fuel injectors on a 2019 Toyota Yaris was quoted at $2150+tax by one mechanic, while another source suggests that OEM injectors typically cost around $800. In some cases, cleaning the injectors manually or using a fuel injector cleaning solution may be a more cost-effective solution.

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Engine issues: clogged injectors, leaking injectors, damaged injectors

Clogged, leaking, or damaged injectors can cause significant engine issues. These problems can affect the entire vehicle and even lead to engine failure. It is important to know how to spot these issues and address them promptly to avoid further complications and costly repairs. Here are some common signs of injector problems:

Clogged Injectors

Clogged diesel fuel injectors can result in poor engine performance. This may manifest as difficulty starting the vehicle, rough idling, a lack of power when accelerating, or even stalling. The clogging prevents the injectors from providing the engine with the optimal amount of fuel it requires, leading to these performance issues.

Another indicator of clogged injectors is a sudden decrease in fuel economy. When injectors are clogged, they cannot meter fuel accurately, causing the engine to burn more fuel than necessary.

Additionally, clogged injectors can cause increased emissions and exhaust smoke. You may notice thick black or blue-colored smoke coming from your engine or exhaust. This occurs when the injectors fail to deliver the proper amount of fuel, leading to excess emissions.

A clogged injector may also trigger the check engine light on your dashboard. The vehicle's computer system monitors the fuel system, and if it detects that the injector is not delivering the right amount of fuel, it will illuminate the warning light.

Lastly, clogged injectors can cause engine misfires, knocking, or loud pinging sounds. When fuel isn't adequately atomized due to a clogged injector, the engine may struggle to complete the combustion process, resulting in these issues.

Leaking Injectors

Leaking fuel injectors are a serious issue as they pose a fire hazard and can cause severe engine damage. Some symptoms of leaking injectors include hard starting, especially when the engine is hot, increased fuel consumption, and a persistent fuel odour inside and around the car.

Leaking injectors can also lead to oil thinning, which can result in catastrophic engine failure. Additionally, leaks can cause hydro-lock, where excessive fuel accumulates on top of the piston, leading to potential engine lock and subsequent damage such as bent connecting rods, broken pistons, and blown head gaskets.

Damaged Injectors

Damaged injectors can also lead to lower fuel efficiency. This occurs when the proper amount of fuel does not enter the engine chambers under the right pressure, disrupting the optimal functioning of the vehicle.

Another sign of damaged injectors is difficulty in starting the vehicle, especially when the tank is full. This could be an indication of clogged or damaged injectors. Engine misfires may also occur due to damaged injectors, leading to potential stalling issues if left unaddressed.

Furthermore, damaged injectors can cause lower RPMs as the engine struggles to receive enough fuel. This can result in damaging stress on the engine as it is forced to work harder than usual.

If you suspect any of these issues, it is crucial to consult a mechanic as soon as possible to diagnose and address the problem.

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Fuel injector issues: high internal leakage, no injection, excessive injection, incorrect injection rate, incorrect injection timing

Fuel injectors are an electrical-mechanical device that opens and closes to allow fuel to enter the engine's combustion chamber. The on-board computer controls the fuel injector by sending out a signal in the form of a pulse. The length of the pulse determines the amount of fuel that enters the engine.

High Internal Leakage

Fuel injectors withstand a lot of heat and moisture, and this can eventually take its toll. A fuel leak could be a sign of a crack in the rubber seals or the fuel injector itself. A leaking fuel injector is a fire hazard and can cause severe and costly engine damage. It is important to identify and address the problem as soon as possible.

No Injection

If your vehicle won't start, it could be because the fuel injectors are not delivering fuel to the cylinders. When the ratio of air and fuel in the engine is off, the motor may not generate the combustion needed to operate.

Excessive Injection

If the check engine light is flashing or illuminated, it could mean that the fuel injector is supplying too much fuel to the engine. This will cause a decrease in overall engine performance and fuel economy.

Incorrect Injection Rate

If your vehicle is experiencing lower fuel efficiency, this could be a sign that the fuel injectors are not working properly. When the injection system is performing correctly, the proper amount of fuel enters each chamber under the right pressure and is atomized accordingly. If this process is disrupted, your vehicle does not have the fuel it needs to function properly, decreasing fuel efficiency.

Incorrect Injection Timing

Injection timing refers to the timing of when fuel is injected into the cylinder, which alters when the combustion takes place. Advancing the timing means moving the combustion up in time so that ignition happens earlier than originally set. Retarding the timing is the opposite, where ignition occurs after the specified time. Adjusting the injection timing can be done to create more power in the engine or to fix a smoking or lag problem.

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Fuel type: quality, additives, lubricity

The characteristics of diesel fuel can be improved through the use of additives, which can be added at the refinery, at the distribution terminal, or by the end user. Additives can be used to aid handling and distribution, improve fuel stability, protect engines and fuel systems, and influence the combustion process.

The most common type of diesel fuel is a specific fractional distillate of petroleum fuel oil, but alternatives that are not derived from petroleum, such as biodiesel, biomass-to-liquid (BTL), or gas-to-liquid (GTL) diesel, are increasingly being developed and adopted.

Diesel fuel quality has improved over the years due to stricter emission standards and preferential taxation policies implemented by governments. For example, the sulfur content in diesel fuel has been significantly reduced to meet ultra-low sulfur diesel (ULSD) standards. While this has led to a decrease in air pollution, it has also resulted in a reduction in the fuel's ability to lubricate the fuel injection equipment. To address this issue, lubricity additives are added to the fuel during the refining process or by the end user.

Lubricity is important because it helps protect the fuel injection system and high-pressure pumps from wear and tear. The fine tolerances of these components, measured in ten-thousandths of an inch, require proper lubrication to function effectively. If the fuel's lubricity is too low, it can lead to shortened service life and potential failure of fuel injectors and high-pressure pumps.

To ensure consistent quality, diesel fuel is standardized, with standards such as EN 590 in the European Union and ASTM D975 in the United States. These standards specify certain properties of the fuel, including cetane number, density, flashpoint, sulfur content, and biodiesel content.

The cetane number is a measure of the fuel's ignition quality, with higher cetane numbers indicating better ignition performance. Most diesel engines, especially high-speed diesels, benefit from higher-cetane fuel as it improves starting, reduces smoke, and enhances overall engine performance.

It is worth noting that the use of additives should be approached with caution. While some additives may have legitimate uses, such as de-icers for cold weather conditions, many aftermarket additives are aggressively marketed with exaggerated performance claims. Modern high-technology diesel engines typically do not require the use of aftermarket additives, as reputable marketers already include all the necessary additives in their fuel.

In summary, the quality of diesel fuel is crucial for the proper functioning and longevity of diesel engines. The use of additives can improve fuel characteristics, but it is important to select additives that are recommended or approved by engine manufacturers to avoid potential adverse effects on engine performance and warranties.

Frequently asked questions

There are several signs that indicate your diesel fuel injectors need to be replaced. These include:

- Engine vibration and rough idling

- Hesitant acceleration

- Check engine light is illuminated

- Reduced fuel economy

- Vehicle not starting

- Foul smell from the engine or engine oil

- Increased engine emissions

Diesel fuel injectors tend to be very reliable and can last between 80,000 to 100,000 miles. However, it is recommended to get them checked or replaced if your vehicle is nearing that mileage.

If the issue persists for long, it can cause significant damage and even disable your vehicle. Bad fuel injectors can lead to lower fuel efficiency, engine misfires, and lower RPMs.

When one injector fails, you have the option to replace just that injector or the full set. Replacing the full set is considered best practice since all the injectors experience similar wear and tear and are likely to have a similar lifespan. Additionally, it can save you money on labour costs in the long run.

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