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How Does a Defect In the Gasoline Direct Injection Pump Effect the Performance of Your Vehicle?

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Gasoline direct injection (GDI) pumps are found near the engine bay and supply accurate amounts of fuel straight to the combustion chamber. Compared to indirect injection pumps, using it is more efficient and it increases the power of your engine. During the recent years, many in the automotive industry are going for GDI because of its advantages in fuel economy and how it reduces emission levels. But what happens when the GDI pump fails?

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Since the fuel injector is responsible for supplying fuel to the engine of your vehicle when the fuel injection pump fails so does the engine. The performance of a fuel injection pump is closely related to the performance of the engine. When there is a fuel delivery issue, the vehicle will starve to death. The vehicle will stall. This is why fuel injection problems are one of the most critical engine problems that you have to deal with. It does not matter if you have encountered a defect in your GDI pump or not, knowing how it works, how it ties to the performance of the engine, and how GDI pumps are different from traditional gasoline-powered units will always come in handy.


Quick Overview of Gasoline Direct Engine Pumps

The automotive industry has been focusing on improved engine efficiency and fuel economy. This is one of the reasons high pressure gasoline direct injection pumps have become more popular. GDI pumps work this way: The gasoline is highly pressurized and distributed directly into the combustion chamber of each cylinder of the engine instead of the standard multi-point injection which gets the fuel into the cylinder port. When gasoline is injected at a high pressure straight into the combustion chamber, the air-fuel mix creates a spiraling motion and greater cooling in the engine’s combustion chamber resulting in higher compression for more efficiency and increase in power. Similarly, the injector inside the cylinder provides the engine more control over the amount of fuel and injection timings, thus saving more fuel. 


GDI also has its own set of disadvantages. The leaner mixture that GDI engines have results in more efficient fuel usage but contributes to much hotter engine operating temperatures compared to port fuel injection engines. Another concern for GDI engines is the intake valve gunk or the carbon build-up. While it is easy to manage remnants of oxidized fuel through regular maintenance, many car owners do not know the need for them to manage the build up until their check engine light turns on. Nonetheless, the benefits of using a GDI pump outweigh the unfavorable conditions it brings. Using GDI engines is also more environmentally friendly. 


Reasons Why a GDI Pump Fails


Now that you know how GDI pumps work and how they are closely related to the engine’s performance, it’s time to know what makes them fail so as to avoid the problem. As you already know, a defect in the GDI pump is a pressing car issue that significantly affects the performance of the engine. If you do not want to deal with it, then avoid doing these things:


  1. Wrong Engine Oil – To avoid premature wear on the camshaft and high-pressure fuel pump follower, your engine oil must meet OE specifications. Ask your engine oil supplier to confirm if an engine oil matches the OEM’s specifications. 
  2. Lack of Maintenance – The main culprit of GDI pumps is a lack of oil changes. When there is wear between the pump follower and the camshaft lobes, the pump is prevented from producing enough piston movement. When there is less pump movement, there is less pressure. Always check the lobes on the camshaft before the installation of a new fuel pump. An issue with lack of power may be improved, however it will never be entirely corrected. 
  3. Failed Temperature Sensors – A malfunctioning sensor cannot cause a pump to fail but it can misdiagnose a high-pressure fuel pump. Direct-injection systems do not only use pressure to locate the pump solenoid, in some cases they use temperature sensors. The information produced by these sensors makes the optimum combustion event, but these failed sensors can throw it off. This can cause fuel trims. If a sensor malfunctions or is generating readings beyond set parameters, the system will resort to a low-pressure safe mode to avoid system damage.
  4. Leaks – Because of the high pressure, a direct injector can experience leaks. When leaks happen while the engine is resting it will lead to severe carbon buildup and a rich fuel reading. A possible wear and a longer cranking cycle can also happen because of leaks. Good thing most systems have a specified resting pressure which is made to maintain a specific amount of pressure in the system while the engine is turned off. There is a scan tool that can monitor the values. There are tests for injector balance and leakdown usually included in an enhanced or factory scan tool. You can use these tests to detect a leaking pump. 
  5. Issues with old calibrations – In the feat to squeeze every bit of energy out of the fuel, every element in the system is performing in danger of driveability issues. Sometimes engineers get it wrong and only find out when the GDI system is in the market and people begin complaining. The pump pressures, pressure solenoid position and camshaft position have a direct relationship with each other. These three together with injector pulses can be calibrated for optimum performance and component life. If you are detecting a driveability problem on a direct-injection car or replacing a pump, make sure the ECU has the most recent calibration as the newer calibration can actually help in solving wear and driveability problems plus you may no longer need to replace the pump. 
  6. Fuel Pump Pressure Solenoid Fails – High-pressure GDI pumps utilize a solenoid in controlling pump pressure and volume. It is done by changing the stroke and/or port location. If the solenoid malfunctions, it goes to a low-pressure setting.
  7. Disregarding the Signs – Some of us like to drive with the check engine light on thinking that it will just go out when we put better fuel in the tank. But this is not the case. A GDI engine with high pressure pump problem will go into a low pressure mode and when this happens the in-tank pump will take control and the injector open time will increase. When the GDI is running, the injector precisely pulses the injector multiple times to come up with the best possible fuel/air mixture. However, when it goes to a low pressure mode, it becomes less precise. The vehicle can still start and run but the performance is reduced and the catalyst may be harmed. It can also cause engine wear. 


Signs of a Failing Gasoline Direct Injection Pump


It doesn’t take a mechanic to know when a GDI pump is failing. When it completely fails, you will be sitting waiting for a tow truck. So it is best if you know the red flags of a GDI pump that is about to go kaput. That way, you’ll be able to have it checked immediately before your car stalls because of a defective fuel pump. Here are some signs and symptoms of a failing fuel pump:


  1. Car is jerking or sputtering at high speeds. A common sign of a failing fuel pump is when your car sputters when driving at freeway speeds. If the fuel pump fails to deliver a smooth flow of fuel to the engine, the engine only ends up getting air when it was expecting to get fuel. This fuel flow interruption makes the engine skip several power strokes which causes the engine to jerk and sputter. When the malfunction is just beginning, the sputtering may only last for a minute or so and the engine gets back to normal. Some drivers may mistaken this as an issue with dirty gas, but with the fuel standards of today, it is more likely a failing pump issue. 
  2. You are losing power when accelerating. If you notice your vehicle losing power when you are trying to accelerate from a stop, chances are you have an issue with your fuel pump. Accelerating demands more fuel so your fuel pump is forced to work harder. When the pump is malfunctioning, it may not be able to keep up with the required fuel demand when accelerating which starves your engine of fuel as it attempts to accelerate. You may need to have your pump checked if your vehicle acts like it’s about to stall when you attempt to accelerate from a stop.
  3. You are losing power when towing a load or driving uphill. When your fuel pump is not functioning properly, it cannot keep up with the demands of driving activities that require more fuel such as towing a load and climbing a hill. These demanding conditions place an extra strain on your pump which causes weak elements to fail. This exposes the flaws of your defective pump. It fails to keep a steady flow of fuel to the engine which causes loss of power.
  4. Your engine surges. A fuel pump that is beginning to wear out has components that wear down at different rates. When the discrepancy gets big enough, it leads to inconsistent pressure in the fuel lines. In these conditions, you may find your car suddenly accelerating for a few moments even when you haven’t hit the gas pedal. This condition is called surging. 
  5. Your engine is not starting. If you overlook all of the other red flags of a failing fuel pump, it will eventually completely go down. Once your fuel pump dies, no fuel will be delivered to your engine, and when this happens you may hear spark plugs firing when you try starting your car but the engine won’t start. There could be other reasons for your engine not to start but you cannot rule out a failed fuel pump. To determine if the fuel pump has died, check the pressure in the fuel lines using a fuel pressure gauge. Your pump has completely failed if it reads zero. Another way is to check your car’s fuse box. A blown fuel pump is another sure sign of a dead pump.


What To Do When You Suspect Your Fuel Pump is Failing


If you’ve encountered any of the signs of a defective fuel pump, it is best to take your vehicle to an auto repair shop. The repair shop will perform a number of tests to determine the exact cause of the problem. Some of the indications of a bad pump can also be caused by other mechanical issues and by doing several tests they’ll be able to confirm whether it is indeed a pump issue or another issue. Typically, they’ll start by checking the vehicle’s electrical system particularly the fuses that regulate power to the fuel system. You are lucky if the issue is just a blown fuse since it is fairly common and is cheap to fix. If this is not the case, then they’ll proceed to checking the voltage of the pump itself using a multimeter. 


Maintenance Tips for Your GDI Engine


To make sure your vehicle’s engine is running smoothly, your GDI system should get a fuel service every 50,000 km. The mechanic will get rid of the intake manifold and clean the valves with the use of a pressurized cleaner. Other methods will be used if the carbon buildup is too much. 


You should not rely on your fuel service alone to keep the carbon build-up under control. You should also go for regular oil changes in between your fuel service appointments. Also, you should replace older spark plugs and add a fuel system cleaner. 


Most of the problems with GDI engine users are because they were not informed of the common issues a GDI engine has and the simple ways to mediate the problem like proper oil maintenance and change intervals. To make sure you get the most of using a GDI pump and avoid unnecessary stress of dealing with a failing GDI pump, then make sure to do these simple maintenance tips. 

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