What Causes Low Fuel Pressure In A Diesel Engine?

A defective regulator, a malfunctioning fuel pump, or fuel line issues are three of the most prevalent causes of low fuel pressure in heavy machinery.

What causes low fuel pressure in a diesel?

Question: I have a 2005 Ford F-150 with 97,000 miles on it and a 5.4-liter V-8 engine. The truck has recently had sporadic power outages. Although the check engine light was not illuminated, a gauge indicated low fuel pressure.

A new battery and two gasoline filters were installed (the first one was dirty). In addition, two tanks of gas containing fuel injector cleaning were circulated through the system. This hasn’t resolved the issue. Are there any Ford recalls that address this issue? Any recommendations you have for improving the issue would be greatly appreciated.

Answer: Your issue could be caused by a number of factors. Fuel pressure must be tested and verified before a solution can be found.

Your pickup has a no-return gasoline system, which is different from the return-based systems used on most cars before to 2000.

On older automobiles, the fuel pump delivered more fuel to the engine than was required. The pressure regulator on the engine kept the correct quantity and returned the rest to the tank. Emissions rules pushed carmakers to use no-return systems, which reduce vapors in the fuel tank.

Ford uses a fuel pressure sensor and a fuel pump driver module instead of a mechanical fuel pressure regulator, with the latter varying voltage to the fuel pump.

A filthy fuel filter, a weak pump, inappropriate tank venting, restricted fuel lines, a blocked pump inlet strainer, and defective electrical control are all common reasons of low fuel pressure. But first, consider a typical blunder. It’s simple to accomplish.

Corrosion is known to cause problems in the fuel pump driver module on Ford trucks from this era. Under the truck bed, near the spare tire, the portion is joined to a steel cross-member. The alloy metal housing of the module reacts with the steel mounting and can corrode to the point where the electronic parts inside are exposed to the elements, resulting in erratic functioning or complete failure. In regions where road salt is used, this is a much bigger issue. I’d consider removing the module for inspection and removing the spare tire. Replace it if it isn’t sealing properly. To prevent corrosion, the replacement item should include rubber grommet standoffs and other improvements. I’m not aware of a service notice or recall from Ford for this issue.

If your symptom persists, I propose checking fuel pressure with a scan tool during low- and high-load operation circumstances. A significant discrepancy indicates a faulty pump or a limitation. Also, check to see that the pump is receiving the proper voltage under all circumstances. The system could be operating erroneously due to a defective pressure sensor. It’s strange that the problem isn’t serious or long-lasting enough for the diagnostic system to detect and illuminate the check engine light. The filthy filter is signaling us to enter the tank for a visual assessment of impurities and the possibility of a clogged pickup strainer.

What are the symptoms of low fuel pressure?

Fuel Pressure Has Dropped Engine misfires, limited acceleration, rough idles, and engine stalls can all be caused by insufficient fuel pressure. If your car has been stalling and your check engine light has come on, you may have a fuel pump failure.

How do I know if my diesel pump is bad?

Is My Fuel Pump Failing? Here Are 8 Telltale Signs That It Is!

  • Noise from the fuel tank. You may hear a loud, whining sound coming from your gas tank if your fuel pump is damaged.

Can injectors cause low fuel pressure?

Low fuel pressure in the rail can be caused by a faulty fuel injector that is stuck open. Misfire codes on a single cylinder at the same time are a common indicator of this.

Can low fuel pressure cause no start?

The engine may not start or run correctly if the fuel pump does not deliver appropriate fuel pressure and volume to the engine. Hard starting, a harsh idle, misfiring, reluctance, and stalling are all symptoms of low fuel pressure. If the fuel pump malfunctions while driving, the engine will not start or will stop operating due to a lack of gasoline pressure.

Fuel injected engines are extremely sensitive to both fuel pressure and volume. Low pressure will make it difficult to start and drive. When the engine is under stress, accelerating aggressively, or cruising at highway speeds, a pump that can produce appropriate pressure but not enough volume may allow the engine to start and idle normally, but it may starve the engine for gasoline and cause a loss of power.

How do you tell if your fuel pump or fuel filter is bad?

Engine repairs can be pricey, and they might keep your car in the shop for a long time. Wouldn’t it be fantastic if you could do something simple and inexpensive to help safeguard your engine and keep it running smoothly? Wait! Yes, there is! Extra care should be used with the fuel filter.


  • You’re having trouble starting your car. If the problem is with the fuel filter, and it is not replaced promptly, your car may not start at all.
  • Misfire or a sluggish idle A clogged fuel filter may hinder the engine from receiving sufficient fuel.
  • The vehicle has stalled. Nobody likes to come to a complete halt in traffic! However, if you’re driving with a filter that’s beyond its prime, that’s exactly what could happen.
  • A component of the fuel system has failed. When trying to push fuel through a filthy fuel filter, electric fuel pumps can fail prematurely.
  • The gasoline pump is making a lot of noise. Sudden, odd noises may be your vehicle’s method of alerting you to a problem.


The gasoline system is monitored by sensors in many automobiles. When the Malfunction Indicator Lamp (MIL) or Check Engine Light illuminates, it indicates that a problem has been detected by the sensors.

These major issues could be solved with a simple, low-cost solution: changing the filter. Fuel filter maintenance should be done on a regular basis and in a timely manner to ensure consistent drivability. A clean filter lowers pollutants and protects your engine and fuel system from damage.


The filter should be changed every two years or 30,000 miles (whichever comes first), however this is a general recommendation. You may want to change your fuel filter more frequently if you drive a lot on unpaved roads or through highway construction, which can kick up a lot of dust and debris. The suggested interval for your specific vehicle should be found in your vehicle’s owner’s manual.

Don’t skip a planned maintenance check, but if you notice any of the five faulty fuel filter symptoms above, don’t hesitate to have a professional look at your car between appointments. When you visit one of Jiffy Lube’s 2,000 sites across North America, a qualified Jiffy Lube technician will:

  • Inquire about your driving style to see if it has an impact on your vehicle’s fuel system.
  • Replace the old gasoline filter with a new one that complies with or exceeds the manufacturer’s specifications.


The fuel filter isn’t the only one that works hard to keep your vehicle running smoothly. When you come to Jiffy Lube, the technician will visually verify the following items:

  • Air filter for the engine. The engine air filter, like the fuel filter, assists to trap debris in the fuel and protects the engine from airborne toxins.
  • Filter for transmission. The filter in your automatic transmission prevents dirt and debris from entering the hydraulic system.
  • Air filter for the cabin. The cabin air filter helps remove dust, pollen, and mold from the cabin, allowing you and your passengers to breathe easier.

If a replacement of any type is recommended, the Jiffy Lube expert will inform you, but no work will be done without your permission.


Preventive maintenance performed by a professional will help keep your car running as it should. Jiffy Lube specialists have undergone extensive training and only use high-quality materials. This is beneficial to you since it means your car, truck, minivan, or SUV will be ready to go and keep going when you need it most. It’s also excellent for your wallet, because little changes, such as changing your fuel filter, won’t escalate into costly repairs if spotted early.

Can a fuel pressure regulator cause low fuel pressure?

Fuel pressure loss can be caused by a defective fuel pressure regulator. As a result, performance issues such as hard starting, rough running, halting, and a lack of power may occur.

What happens when your fuel pressure sensor goes bad?

The ECU will not provide the correct amount of fuel to the engine if the fuel rail pressure sensor is damaged. It will be tough to start your vehicle as a result of this.

When this problem first develops, it will most likely take several attempts to start the engine. However, if the condition worsens, it will take more and more attempts to get started. It frequently starts and then shuts off. The engine will eventually stop starting.

How do you check a bad fuel pump?

  • Keep an ear out for the gasoline pump: Place your ear near the petrol tank and ask someone to turn the ignition key to “on.” If the gasoline pump is running properly, it should create an audible noise.
  • Whack the petrol tank with a rubber mallet: Have an assistance crank the engine while you whack the fuel tank. If the vehicle starts during this method, the electric motor inside the pump is most likely broken. Whacking the tank causes enough damage to the motor to get it going – but only for a short time.
  • Starter fluid should be used: Please be aware that this method has the potential to inflict personal injury as well as engine damage. Try it at your own risk, and make sure you have the necessary safety equipment on hand, such as a fire extinguisher. Wear your safety glasses at all times. On a diesel engine, do not use starter fluid.