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9 Symptoms To Detect a Weak Fuel Pump on a 7.3 Powerstroke

Fuel pumps deliver a steady supply of fuel to keep your engine alive. A weak or failing fuel pump can ruin the performance of your truck by crippling acceleration and stalling your car. Fortunately, telling if your fuel pump is failing is easy if you have a keen eye and ear.

Symptoms to detect a weak fuel pump on a 7.3 Powerstroke include a hard start, rough idle, and no start; an engine that stalls or fails to accelerate; erratic revving at high RPM; excessive vibrations; and engine power outages or check engine light. 

A physical examination might reveal that it is faulty. If not repaired, this problem could lead to total engine failure. This article explores nine common 7.3 Powerstroke fuel pump failure symptoms, possible causes, and fixes to a failing fuel pump.

1. Hard Start or No Start

Reviews from 7.3 Powerstroke engine users show that when the fuel pump starts failing, you will experience hard starts or no starts when you try to crank your engine.

A leaking or clogged fuel pump starves the engine of enough fuel, and this creates starting challenges. You can crank the engine several times, but it will not start. 

A weak pump loses pressure and starves the engine of adequate diesel. At start, an engine requires a lot of fuel, which a weak fuel pump cannot deliver. You may hear a sputtering sound while starting your 7.3 Powerstroke with a hard start. 

The video below further explores the no-start issue in the 7.3 Powerstroke diesel engine.

2. Rough Idling and Misfiring

After a hard start, your 7.3 Powerstroke engine can idle roughly if the fuel pump does not generate adequate pressure. Your engine will sound erratic, and you may also experience popping and sneezing sounds as it backfires. 

Low fuel pressure will lead to a poor air-fuel mixture and weak combustion. This weak combustion is felt as misfires on idling and acceleration.

3. Low Performance and Hesitation During Acceleration

A 7.3 Powerstroke engine with a weak fuel pump will hesitate to accelerate, and the throttle will feel less responsive.

Your engine will sputter under heavy acceleration due to low oil pressure, and your vehicle will jerk under load and slug while going uphill. 

The jerking and sputtering will increase as RPMs increase. The acceleration may smooth out for a few moments then it freezes again.

This cycle will repeat itself over on low revs. Once you cross a certain RPM, the engine may stall. Generally, your throttle will feel less responsive than normal.

4. Engine Stalls

If your engine stalls at idle, low speed, or even high speed, you may need to check your fuel pressure. A weak fuel pump causes fluctuations in fuel delivery to the nozzles and cylinders, stalling the engine. 

When fuel pressure drops too low, the engine is starved of fuel and seizes. Stalling can be particularly dangerous when driving on the highway.

The chances of being rear-ended when your car stalls on the highway are high. Stalling can also lead to loss of steering control and brakes as the hydraulics pump seize the moment the engine stalls. 

I recommend getting your fuel pump checked and your car diagnosed after a few stalls to minimize the chances of accidents.

5. Surges and Sputters at High RPM

One of the most effective ways of detecting a faulty fuel pump is revving your 7.3 Powerstroke engine to high revs between 2800-3000 RPM.

This is the peak torque and horsepower range for the engine. If there are any issues with the engine, they will be easily detected here. 

A weak fuel pump will not maintain the required pressure, and first, your engine will have difficulties getting to 2800 rpm.

Once it gets to this RPM range, you will notice that it coughs and sputters intermittently. This coughing, coupled with misfires, will result in a chaotic engine roar. The engine will gain and lose RPM, and the Rev counter will be erratic. 

If you are driving on the highway, you will find your truck surging and jerking on these high RPMs. The engine sputters and vehicle surges are warning signs that, if not sorted, might culminate in the engine dying.

6. Periodic Power Outages

Another symptom of a weak fuel pump on 7.3 Powerstroke engine is periodic power outages. Your truck may abruptly lose power, and the engine will freeze. The dashboard may display the low fuel sign, and the engine may fail to gain acceleration. 

After switching off the truck and then cranking it after a while, it may regain power and then lose it after moments of driving. These power outages will likely increase in frequency as the fuel pump deteriorates.

Eventually, as the fuel pump gives in, the engine will stall completely until the fuel pump issue is addressed.

7. Excessive Vibrations

The misfires and surges in power can cause massive engine vibrations. Incorrect combustion in the engine chambers due to the fuel pump not delivering adequate fuel will lead to rough engine operations.

You will notice vibrations that were not evident before, especially when accelerating harshly.

8. Whining Fuel Pump Noise

The fuel pump can be found on the driver’s side frame rail in post-1999 Powerstroke trucks. When the fuel pump starts failing, you will notice a whining noise that sounds like your pump is trying to compress air.

The noise may sound like a guggle as the pump nears total failure. This whining noise is a sign of a weak, failing fuel pump. 

You can confirm if the pump is failing using a simple test. You need a diesel can with a significant amount of diesel and a short fuel line.

Follow the following steps: 

  1. Disconnect the fuel line from the back of the fuel pump that connects it to the truck’s diesel tank. 
  2. Dip your short fuel hose into your diesel can and ensure it is in contact with the diesel.
  3. Turn your key and see if your pump is as noisy as when it is pulling from the main tank.

If it is not as noisy when pulling from the can, then there is some restriction within the fuel lines, straining your pump. If the pump is still noisy when pulling from the diesel can, it is faulty.

The whining noise of a faulty pump will be easy to detect and get louder as the pump deteriorates.

9. Check the Engine Light 

This symptom comes last because this light can be triggered by many other factors. This dreaded light tells the motorist that something is wrong with their motor and is about to cause them money. 

A faulty fuel pump distorts your engine’s air-fuel mixture. A faulty air-fuel mixture will cause misfires, which will be detected by the Engine Control Module (ECM), which will trigger the check engine light. 

You will need a digital diagnostics scanner to read ECM fault codes and establish what is wrong. The fuel pressure sensor will also easily detect fuel pressure loss and send signals to the ECM. Typically, fuel-related issues detected by the fuel pressure sensor will trigger the P0190 fault code

Misfires due to poor air-fuel mixture might have other causes. You will need to conduct advanced diagnostics to determine the specific trigger for this problem, which may require a physical inspection of the fuel pump.

Common Causes of 7.3 Powerstroke Pump Failure

The following are common causes of 7.3 Powerstroke engine pump failure:

  • Clogged fuel filter. The fuel filter cleans the fuel that enters the engine. This filter accumulates dirt over time and must be changed at intervals. When it gets clogged, it creates a restriction that can drive your fuel pump into a slow, agonizing death.
  • Clogged fuel pump. The pump itself can accumulate dirt, including diesel particulates. This dirt chokes your fuel pump leading to its subsequent failure.
  • Bad fuel lines. Fuel lines span several meters connecting the tank and injection system. These lines run under your truck’s floor, and you should check these regularly to ensure they are intact. Compression of fuel lines can restrict fuel flow and strain your fuel pump.
  • Defective fuel pressure regulator. Fuel pressure regulators control the fuel pressure within your vehicle. A faulty regulator can build up too much pressure within the system, straining your fuel pump.
  • Freezing winter conditions. This freezes your fuel pump, leading to imminent failure until the pump is unfrozen.
  • Electrical faults. Faults within your truck’s electrical system can also destroy your fuel pump since it is powered by an electrical current.

Detecting a Faulty Fuel Pump

The best way to detect a faulty fuel pump is to measure the fuel pressure using a fuel pressure gauge. These are available in the market, but you will find them in most garages. A physical inspection of all fuel system components should follow a low fuel pressure reading.