Diagnosing issues with the 7.3L or 6.0L Powerstroke engines is not necessarily easy. Teaching you how to be a diagnostic pro is not realistically possible through this one article (that takes years of experience); however, we can help you get yourself on the right path by sharing some tips we've learned over the years.

The biggest tip: collect as much data as you can. Before you post a question on Facebook or give your favorite shop a call, collect some data first so that those who are trying to help you have all the data they need. Whether you’re asking for help or not, data is your best friend and without it all you’ll be doing is throwing darts, hoping one of the darts (aka new parts) you throw at the truck hits the bullseye and fixes the problem. You’ll save a ton of money if you approach the issue with all the information possible.

Data Collection: First and foremost, get yourself a quality scanner that’s compatible with your platform, like AutoEnginuity for example. Simple scanners, like those you’ll commonly find at AutoZone (and other large auto parts retailers), will likely not be able to read all the codes in a 7.3 or 6.0 PCM.
Once you have a good scanner, regardless of the issue, collect all the trouble codes and write them down. A quick note regarding codes, if you had a check engine light on, but it went off, you still have a code in your system. If you can’t see it with your scanner, that scanner is likely not the right one for your platform.

Once you’ve checked the codes, do some data logging. If the truck runs well enough to drive it safely, go for a drive and do your best to duplicate the concern/problem your truck is having. Watch and record things like ICP, IPR duty cycle, and turbo vane position. Exactly which items you’ll need to watch depends on what the issue is, the prior mentioned are the most commonly used parameters for diagnosis.

Check the fuel pressure. This is NOT something that can be checked with a scanner for any 7.3 or 6.0 and is a very important piece of info to have. You’ll need to tap into the fuel system with a mechanical or digital gauge. On a 7.3, this is most commonly done by removing a plug just above the fuel bowl heater on the backside of the fuel bowl. For a 6.0L, it’s in a similar location on the fuel filter housing, but it’s on the bottom portion, and it points toward the driver's side fender. Remove the plug from your fuel bowl, attach the gauge, and test. We have these gauges available as well as any adapter you’ll need; the link is at the end of this article.

For a 7.3L, 60-70 psi is normal fuel pressure. For a 6.0L, it’s 45-60 psi. Outside poor running issues, low fuel pressure on either engine will cause injector damage.

 

Some Common Items Worth Sharing

Lack of power and boost. A very common issue for 6.0L owners. This issue is most commonly caused by vane issues within the turbocharger itself. The 6.0L turbocharger has variable vanes that adjust based on the PCM’s demand for boost. For various reasons, these vanes stick.

The second most common reason for underperforming turbos is EGR related and is very often overlooked. The Exhaust Gas Recirculation (EGR) system reintroduces exhaust into the intake for emissions reasons. The EGR valve lives in a very dirty environment and can stick open. When it does, it leaks exhaust pressure back into the intake preventing the turbo from creating boost.

For 7.3 owners, lack of boost is often due to up pipe exhaust leaks. When leaking the up pipes will leave dark soot deposits on the firewall that are easily visible when looking down behind the engine from the engine bay.

Dirty IPR Valve. It is extremely common for rough running issues to be related to a dirty IPR valve, for both the 7.3 and 6.0. These valves don't fail often, more commonly they're just dirty. Cleaning your IPR valve screen should always be high on the list of things to do.  

 

Helpful links:

Forums are your best friend. Nowadays we tend to look at Facebook groups as the go to, and those groups are definitely helpful, but the forums take it to a whole new level. Forums like those linked below include full diagnostic trees (step-by-step diag plans), wiring diagrams, oil path diagrams, images of problem areas, and really all the diagrams and images you could need for any problem.

6.0L Fuel Pressure Testing: https://www.ford-trucks.com/forums/1163747-how-can-i-test-fuel-pressure-on-a-6-0l-diesel.html

7.3L Fuel Pressure Testing: https://www.powerstroke.org/threads/testing-fuel-pressure-on-7-3.1253450/

Every 7.3 issue you could think of explained: https://www.ford-trucks.com/forums/1592056-1999-2003-ford-super-duty-and-excursion-7-3l-psd-tech-folder.html

A list of all codes for 7.3 trucks: https://www.ford-trucks.com/forums/834986-7-3-l-trouble-codes.html

A list of all codes for 6.0 trucks: https://www.powerstroke.org/threads/6-0-trouble-codes-list.123983/

The 6.0L Powerstroke Technical Manual (aka the 6.0L Bible). These links are often removed so we’ll do our best to keep this one updated: http://www.backglass.org/duncan/ps60_manual/

 

Some helpful parts and tools:

AutoEnginuity Ford Enhanced Scanner: https://www.riffraffdiesel.com/autoenginuity-total-ford-enhanced-bundle/

Fuel Pressure Gauge: https://www.riffraffdiesel.com/fuel-pressure-0-100-psi-ev2/

Miscellaneous 7.3 Tools and Related Parts: https://www.riffraffdiesel.com/tools-misc-99-03/?page=1

Miscellaneous 6.0 Tools and Related Parts: https://www.riffraffdiesel.com/tools-misc-03-07/

***Disclaimer: The information provided on this blog is for informational purposes only. We share our knowledge and experience, but we are not liable for any damages, injuries, or losses that may occur as a result of using this information. Situations are rarely cut and dry in the automotive world. Your situation will likely be somewhat different than what we describe here.  Use your best judgment and always consult a qualified professional for automotive repairs and modifications. Your safety is your responsibility.