Diesel Fuel Pump Failure Symptoms

It seems pretty vital for the diesel engine to have a functional fuel pump. In essence, a failed diesel fuel pump may cause some serious problems for the engine and the car’s overall performance. Thus, it seems pretty essential to tackle diesel fuel pump failure symptoms and fix the problem quickly.

The fuel delivery system of diesel engines supplies the required amount of diesel and at a precise pressure. Without such action, the vehicle would not function properly. If your car makes use of a diesel fuel pump, it would be best if you maintain it and ensures it remains in good condition.

Nevertheless, there are a plethora of reasons the diesel fuel pump would develop faults. One of such is the unavailability of sufficient fuel, which causes that car’s component to pump air. Another significant issue that could damage the fuel pump of diesel vehicles is engine breakdown.

Diesel Fuel Pump Failure Symptoms

The principle of the diesel fuel pump system is one thing that car owners should know. Kindly note that the diesel delivery system appears relatively easy. The fuel moves from the tank to the conveying metal pipe that supplies fuel to the engine.

Inside the diesel fuel tank lies the electric pump that starts working as you turn on the vehicle’s engine. It applies some pressure that pushes the diesel fuel through the pipe. The engine receives the exact amount of fuel and at the right time when the high pressure sprays the fuel through the diesel injectors.

In essence, if any problem arises that results in the diesel injector pump not pumping sufficient fuel, it could further lead to the engine knocking. With the frequent use of this car part, you may notice some issues with the diesel fuel delivery system occasionally.

With these in mind, you should take note of some common signs the car may exhibit when faced with diesel engine fuel pump problems.

diesel injector pump troubleshooting

Weird Sounds

When the fuel pump of cars with diesel engines goes bad, you may soon start hearing some unusual noisy sounds. This sign seems pretty common and it is different from the normal sound that fuel pumps make.

Remember, when you turn on the engine the diesel fuel pump gives off some sounds, which gradually goes away as the car moves. Nevertheless, a faulty diesel fuel pump would give off a squeaky sound, and such squealing would tell you that you should take the vehicle to a mechanic to fix the problem.

The Car Doesn’t Start

There are many reasons why your car won’t start, and one of them is a bad diesel fuel pump. This fuel pump failure symptom would make cranking the diesel engine takes a longer time. So, if you notice that the car wouldn’t come on when you push the button or turn the key, you should check the fuel pump.

Delayed Acceleration

The car may exhibit an acceleration hesitation even though that doesn’t occur on a normal day. It is pretty typical for vehicles to accelerate from “stop” without any problems. Thus, you can drive with more ease along a busy road with traffic.

Nevertheless, you may notice a delay when you step on the gas pedal due to a failing fuel pump. This issue seems pretty annoying, and drivers could be at risk if they can’t get the car to respond quickly. Kindly note that it could result in some further damages if not fixed quickly.

Engine Stalling

Have you ever noticed you’re a sudden engine stall in your driveway? Did you stop to check the diesel fuel pump? This symptom tells you that there may be something wrong with the fuel pump, and there is a need to fix it. Leaving the problem to linger for too long may be dangerous, as you may notice the car idling while you drive on the highway.

Engine Misfire

When a vehicle’s engine misfires, you would feel the effect within the car and also hear the sound. Without a doubt, such an issue may cause some serious damage to the engine. Since there is no sufficient supply of fuel to complete the combustion within the engine cylinders due to a bad fuel pump, the engine starts misfiring.

Wrong Fuel Pressure

Your car wouldn’t run well if it does not maintain good or correct fuel pressure. In essence, the wrong fuel pressure makes the vehicle malfunction and reduces its efficiency. If you notice possible issues with a reduced diesel fuel pressure, it could be due to a faulty fuel pump. Thus, it would help if you diagnose and fix the issue quickly.

Check Engine Light Goes On

It is a general rule for the check engine light to suddenly come on when there is an issue with the engine. This case remains persistent when it comes to a failing fuel pump. You would agree with me that the engine starts facing some problems if the fuel pump cannot supply sufficient fuel for its running.

Thus, the check light turns on and you can conduct a further diagnosis to be sure that the diesel fuel pump is responsible for this problem. You can further troubleshoot using the OBD system to help you solve this problem.

Diesel Fuel Injection Pump Calibration

You must have noticed some cars emitting black smoke from the exhaust pipe, right? Well, such a scenario may be due to a “wrong” diesel fuel pump timing and fuel atomization. Thus, the unburn particles from the combustion chambers forcefully through the vehicle’s exhaust.

Nevertheless, there is a way folks can correct the actions of the diesel fuel pump. This process involves the proper calculation before the correction takes place (calibration and trimming). The effective calibration of the diesel pump reveals whether or not the pump needs an overhaul.

Hence, some persons perform the test when they notice symptoms of a faulty diesel primer pump or diesel lift pump failure symptoms. Kindly note that the high-pressure diesel injection pumps can be calibrated using specialized test tools.

There are a few effective machines that test the diesel pump and help calibrate the fuel supply. With these apparatus, you can adjust the fuel volume and pressure for each diesel engine cylinder, and adjust the supply speed.

Leaving out further details, here are a few things you should know about the processes involved in this diesel injector pump troubleshooting.

  • Get your fuel pump test ready and mount the diesel pump on your test stand, and by now all test nozzles should be adjusted to the specified nozzle opening pressure. You can check this out on the pump stand manual.
  • Once done, there are a few details (pump delivery requirements) that you would see, and you have to set them as desired.
  • The first setting is for the fuel rack, and this signifies the distance that stands between the pump housing flywheel end and the fuel rack end. Kindly note that the fuel rack end should appear within 0.005 inches of the actual setting and you can use a depth of 2-inch.
  • Then work on the holder assembly and nozzle assembly numbers
  • Then, use a suitable calibrating oil and it should be within temperatures of 110 to 120 degrees F.
  • Kindly run a minimum stroke of 250 to help you achieve accurate calibration. You can increase it to 500 strokes if the pump delivers diesel fuel below 75cc.
  • If after the whole process you successfully achieved the desired diesel fuel delivery, it would help if you try to recheck the nozzle’s opening pressure. Get the nozzles changed or repaired if they don’t fall within the specified limits.

The Calibrating Stand

It is recommendable for folks to make use of calibrating stands with 10HP or more, and you should try to follow the manufacturer’s instructions when using the stand. Before you get started with the test, kindly ensure that the calibration stand is in good shape, and look out for lubrication and other common checks.

Again, it would help if you ensured that the pump crankshaft can rotate above 360 degrees before you mount on the calibration stand. This action would prove to be more helpful if there is a pump overhaul.

Final Words

One of the common concerns of most car owners is how to know if the diesel injection pump is bad and ways to get such an issue fixed. You might be wondering why this issue seems like a serious problem. Well, the fuel pump supplies the right amount of diesel and at the correct time to the engine.

Thus, if there are any diesel fuel pump failure symptoms, the engine would start receiving lesser amounts of diesel. In extreme cases, there would be no fuel supply and that could lead to engine knocking. Hence, it is pretty crucial to tackle such problems with great urgency.

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Hi There, I am R. Hasan Tito, a mechanic, and owner of this website. My friend and I created this website to share our knowledge, expertise, and experience with our fellow mechanics' community and car users. I am a specialist and certified automotive mechanic (Both Heavy Commercial and Private Cars). I have been working as a mechanic for over fifteen years. I worked for a long time at Global Rebound Automotive companies (Toyota, TATA, BMW, Nissan, TVs, and Others ) as a Mechanic and Mechanics Supervisor.

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