5 Symptoms To Detect Bad Injector Failure On 7.3 Powerstroke

Experiencing noise from the powerstroke? Turns out, the injector could go bad if it’s too old. It’s nothing new. This can beget a whole lot more problems, especially in a 7.3 powerstroke. So, what are the 7.3 powerstroke bad injector symptoms that suggest your next move? 

Well, for a 7.3 powerstroke bad injector, you will experience rough idles, misfire, no cold start, fuel efficiency low, and a heck lot more. Sometimes, if you do get it started, the runtime is just horrible. Oil leaks, hard starting, and decreased fuel economy are common as well.

7 Most Common symptoms of Bad Injector on 7.3 Powerstroke

7.3 Powerstroke Bad Injector Symptoms: (Easy Diagnosis)

There are quite a handful of problems that can happen due to a bad 7.3 Powerstroke injector. Let’s look at all of them: 

ProblemsPossible solutions
Misfire And Rough Idle1. Cleaning the injector
2. Sealing powerstroke leaks
3. Adding an O-ring to the injector
4. Replacing the injector
Horrible Running1.Cleaning the injector
2. Replacing the injector
3. Adding an O-ring to the injector
No Noise from the injector1. Replacing the valve
2. Replacing glow plug
3. Replacing under valve cover harness
Poor Engine Performance Have To Slip The Clutch1. Cleaning the injector
2. Replacing the injector
3. Adding an O-ring to the injector
Hard Starting1. Cleaning the injector
2. Sealing powerstroke leaks
3. Adding an O-ring to the injector
4. Replacing the injector
Decreased Fuel Economy1. Replacing the injector
2. Adding an O-ring to the injector

#1- Misfire And Rough Idle

In a diesel engine, you will need running fuel, air, and a proper firing for a good idle. If the cylinders are not firing correctly, the glow plug won’t start the engine, causing misfire, and rough idles. You can try cleaning the injectors and seal the leaks. However, in most cases you will need to replace the injector. 

#2- No Cold Start

We all know that injectors are responsible for delivering fuel to your engine. When the engine is cold, a bad or leaking injector can’t do its job properly. So, the engine won’t start. However, if you crank up the motor and heat it up, the truck may start just fine. 

#3- No Power/Low accelerating/ Low Torque 

You will notice that the truck isn’t accelerating as fast. On top of that, you will feel sluggish while riding uphills. Most probably it’s oil leaks, which an O-ring should fix.

#4- Horrible Running

Sometimes, the injectors can get clogged or damaged and they can’t deliver the proper amount of fuel to the entire engine. This leads to a horrible riding experience in any road type. You don’t specifically need to ride uphill terrain for this.

#5- Have To Slip The Clutch More

Alongside a poor engine performance, you need to slip the clutch for longer. What this means is, your engine isn’t getting enough power to turn the wheels. Jerking, stalling, and even difficulty in gears shift isn’t rare either.

#6- Hard Starting

If the injector problem isn’t too far fetched, then your truck will start, but the starting will be longer than usual. Generally, a regular injector cleaning will do the trick. But get an O-ring to fix the problem for good. 

On rare occasions, you will need to replace all the injectors, as you don’t know which one went bad. 

#7- Decreased Fuel Economy

When the injectors are not spraying properly, and the engine is not getting enough fuel, you may face a decrease in fuel economy. Your engine should run lean at this point. 

However, this root cause of the problem can also be a dirty air filter, broken glow plug, or even a faulty oxygen sensor. Don’t just blame it on the poor injector every damn time. 

How To Diagnose Which Injector Has Problem In A 7.3 Powerstroke

To diagnose which ignitor has the problem, you will need a diagnostic interface. Any regular interface will do the trick. You can try the BAFX OBDII as it’s highly accurate.

Now follow the steps below to diagnose a 7.3 Powerstroke bad injector:

  • First, you will need to download a software called the FORscan lite from the app store or play store. You can also google the app for your phone. 
  • Now, connect a diagnostic scanner device to the computer socket and start the engine. 
  • Let the idle run for a few minutes while monitoring the live data stream from the scanner. 
  • Pay close attention to the injector pulse width readings. You should see all of the injectors firing at a regular interval. 
  • If one of the injectors is not firing, or if the pulse width readings are erratic, then that injector is most likely the problem. 
  • You can also do a sound check. Bad injectors should sound more quiet than the good ones.

Watch this video to get all the steps correctly. Replacing the Fuel Injectors in a 7.3 Powerstroke Diesel | Ford F-250

How To Fix Or Replace A 7.3 Powerstroke Bad Injector?

Fixing a 7.3 powerstroke bad injector is fairly simple when you have some steady hands. So, let’s begin:

  • Disconnect the battery terminals, especially the negative ones. Plus, get the fuel lines separated as well. 
  • Now, unscrew the injector from the cylinder head and take the injector out. All you need is a screw driver for this. 
  • Clean out the injector bore in the cylinder head with a wire brush or a shim. This will ensure maximum cleaning from debris or dirt buildup. 
  • If you see leaks, get an O-ring to fix it in place with the injector. 
  • However, if the injector has gone wild, get a new injector and place it in place of the old one. Reconnect the battery terminals, and fuel lines. 
  • Finally, start the engine and inspect for any leaks. Seal any leaks and wallah. 

Pro-Tip: If you don’t have the right tools at hand, don’t attempt the fixing process, as you can break the valve or injector housing.

Bad Injector Symptoms related (FAQs)

Where Is The Injector Pump On A 7.3 Powerstroke?

The injector pump on a 7.3 powerstroke is located on the side of the engine near the top. It’s basically a black, rectangular box with a large hose attached to it. To access it, you need to disconnect the battery terminals and then the fuel lines first. 

How Often Do Diesel Injectors Need To Be Replaced?

Diesel injectors are designed to last anywhere from 150000 miles to 200000 miles of a diesel engine with proper maintenance. But there are also several factors that can cause them to fail prematurely like contamination from fuel, water or debris. If you ever find noise from the injectors, hard starting, poor idle, etc., get the injectors inspected and changed.

Why Is The Number 8 Injector On 7.3 Powerstroke Different?

The number 8 injector is different because it is the last one from the oil pump and so that fuel can reach it properly. So, to combat filling problems, misfire, and rough idle, the shape of the 8 inject had to be tweaked. After changing the shape, the 8 injector works flawlessly in any.

When To Replace 7.3 Injectors?

Whenever you notice a problem like no cold start, no power,  low fuel efficiency, sloppy acceleration, you will need to replace the 7.3 injector. Usually after every 150000 miles, the injector needs a replacement. 


The fuel injector is responsible for injecting fuel into the engine. So, if any of the injector goes bad, then the engine won’t get the right amount of fuel to function. 

In most cases, you will notice misfires, rough idle, and poor engine stability. Sometimes, your truck won’t even start when the engine is cold. 

You will need to diagnose the damaged injector and replace it pronto. For leaks and noise, you can try adding an O-ring to the injector. Hopefully, this fixes the problem. 

Here are other powerstroke related articles links you might like:

5 Symptoms To Detect  Bad Glow Plug Relay On 7.3 Powerstroke

8 Common Bad Fuel Filter Symptoms 6.0 Powerstroke (Easy Solution)

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Mahir Ahmed


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