DD15 Bad Fuel Pump Symptoms - Here's Why It Can Fail

The DD15 is a top-of-the-line heavy-duty diesel engine that is simply impressive and powerful. By offering less complexity along with more durability, it is undoubtedly one of the most reliable diesel engines in the market. With great fuel efficiency and top-notch performance, the DD15 engine definitely has all the characteristics necessary for today's industry.  

Fuel supply problems highlights

• Level of importance:Very high
• Can you drive?Usually, no
• DIY inspection:Possible
• DIY repairs:Mostly,impossible
• Price of repair:$300 - $650
• Commonreasons:Fuel pump, fuel filter, fuel lines, EVAP system, electrical problems
• How to fix:Check the pump, verify it has power, check the fuelfilter

Bad Fuel Pump Symptoms

The fuel pump in your DD15 diesel engine is responsible for inserting fuel into the combustion chamber for the engine to run efficiently and smoothly. The electric pump inside the diesel fuel tank immediately begins to work when you start the engine. The fuel pump applies enough pressure to push the diesel fuel through the pipe to get the fuel flowing properly.      

Therefore, if the fuel pump reaches the point of failure and affects the engine, it will take much more than simple maintenance to get your DD15 engine back running again. You can test a diesel fuel pump with a fuel pressure gauge to double-check that the right pressure is being put out. It is common for shops to recommend replacing the fuel pump when the main problem is due to just the O-ring going bad.  

It is also good to remember that the DD15 fuel pump is lubricated by fuel. So without enough lubricity in the fuel, you will be left with a huge mess of metal shavings in the entire fuel system and probably end up spending a lot of money to clean up the mess and in repairs. So to avoid spending thousands on new parts and potential risks on the road, it is better to be familiar with the most common bad fuel pump symptoms that you may face with your DD15 diesel engine.

• Delayed Acceleration

Delayed acceleration is one of the most common symptoms alerting you that your vehicle may have a fuel pump issue. A bad fuel pump will cause acceleration hesitation and you will experience a delayed response when you step on the gas pedal. Facing such conditions can not only be annoying but also very dangerous on a busy road.  

With a failing fuel pump, it will not be able to provide the engine with enough fuel at the correct time. So when you step on the gas to accelerate, the engine of your vehicle will not be able to support your need promptly and cause a delay. If the fuel pump is not fixed quickly, the engine and other related parts will get damaged and begin to malfunction.    

• Sputtering Engine/Power Loss

The fuel pump not only pushes gas to the engine when you start your vehicle but also pumps gas to meet your desired speed on the road. So if the fuel pump fails to produce a continuous stream of gas to support that speed, the engine in your vehicle will sputter and may stall. A failing fuel pump will end up starving the engine of the necessary fuel and will cause the engine to sputter and suffer major damage.  

It can be possible that your engine may not sputter, but lose power under certain driving circumstances. With the fuel pump not being able to transfer enough fuel to the engine, it may not be able to handle going up steep hills or driving up steep inclines. Therefore, under such strenuous conditions, your vehicle will lose power without enough fuel to handle the pressure.  

• Surging Engine/Power

Remember, the engine requires the right amount of fuel at the correct time. Along with not being able to send enough fuel, a faulty fuel pump can also send too much fuel to the engine and cause sudden power surges. Sudden spikes and then drops in speed can be extremely dangerous while driving and should be properly diagnosed and fixed urgently.     

• Unusual Noisy Sounds

When the DD15 engine is turned on, the diesel fuel pump makes a low humming noise and it gradually fades away as the vehicle gets moving. However, a damaged fuel pump can make some unusual noisy sounds. Whining or squeaky sounds coming from your gas tank is a very common sign of a failing fuel pump and you should not ignore such symptoms.     

• Low Fuel Efficiency

Since a faulty fuel pump can push too much fuel into the engine, your vehicle will end up burning more gas than usual. If you notice any unusual gas mileage decrease with your vehicle, you should track between fill-ups to be sure that a low fuel efficiency issue exists. A gas mileage decrease is a common indicator that you may be dealing with a dying fuel pump.     

• Check Engine Light Coming On   

Although the check engine light can come on for numerous reasons, it is a general rule to assume that something is wrong with the engine. As a failing fuel pump is not able to supply sufficient fuel for the engine to run properly, it starts to develop major problems of its own. Therefore, if your check engine light suddenly comes on, it is better to perform a further diagnosis to make sure that the fuel pump is the main reason behind this issue.        

Here's Why the Fuel Pump Can Fail

As the fuel is sprayed from the high pressure through the diesel injectors, the DD15 engine can receive the required amount of fuel at the correct time it is needed. So if there is any fuel pump failure, the engine will not get the necessary fuel needed to continue functioning properly. While the fuel line pressure will be lost without a working fuel pump, the engine will not be able to fire up without the delivery of any fuel.

Low fuel level and contaminated fuel clogging up the fuel filter are two main reasons behind the fuel pump failing in your vehicle. No matter how durable or powerful the DD15 engine may be, your vehicle should never run out of fuel. With low fuel level, it prevents your vehicle from functioning as it should and puts an unnecessary amount of pressure and strain on the fuel pump.

The fuel in your vehicle is needed to flow through different parts of your vehicle to make everything run smoothly. However, if the fuel is contaminated, it cannot flow freely to certain parts and causes disastrous malfunctions. One of the most common forms of fuel contamination is having foreign particles within the diesel fuel.

Microscopic fragments containing metals, dirt, and grime can get into the fuel in your vehicle and become the reason for the majority of fuel-related problems. Heavily contaminated fuel will end up clogging up the fuel filter with particulates and other foreign materials. Once the fuel filter begins to clog, it puts more strain on the fuel pump to keep the continuous flow of fuel going to the engine.

The fuel filter is responsible for capturing foreign particles within the fuel before they can reach the engine. With the fuel filter being clogged up, the fuel cannot flow easily through the filter and therefore the correct amount of fuel fails to reach the engine. Also, the fuel pump has to work harder than it is designed to handle and eventually overheats and fails prematurely.  

Conclusion

The DD15 engine depends on the fuel pump to supply a precise amount of fuel at the right time for the engine to function properly without any glitches. Therefore, if you have a bad/faulty fuel pump and cannot provide the engine with the necessary amount of fuel, the DD15 engine in your vehicle will eventually fail. Fortunately, fuel pump issues leading ultimately to engine failure happen gradually and there are some easily detectable tell-tale signs to look out for.

If you are aware of the symptoms and main causes related to fuel pump failures, you will have the opportunity to take action before you're left with a bad fuel pump and a damaged engine. So, if you happen to notice any of the common symptoms mentioned above, it just might be the right time to get a new fuel pump. Just make sure you get the proper diagnosis and only replace the parts that are actually behind the main problem.