Posted by Zach Cantrell on 1/26/2023 to
We want to share with you some of the common issues and failures we see with the
7.3 Powerstroke injectors after many years of rebuilding, and working on them.
First, we need to know how a Hydraulic Electronic Unit Injector (HEUI) works. To
keep it simple and without overcomplicating things, let's break it down as follows,
the electronic, oil, and the fuel side. The solenoid (electronic), when energized acts
like a magnet and pulls up the armature plate and allowing oil to go past the poppet
valve (oil side) and apply oil pressure to the intensifier piston and plunger. Once the
pressure is applied, it pressurizes the fuel until it overcomes the nozzle spring
pressure, it allows the pintle in the nozzle (fuel side) to lift and fuel can then spray
from the nozzle. Once the electrical current has been removed from the solenoid it
allows the poppet to close. The high pressure is then relieved from the fuel cavity
allowing the pintle to close and stop fuel flow out of the nozzle. The fuel cavity is
then refilled by your fuel pump.
Now that we have a basic understanding of all the moving parts and how they all
work, let's move to the common issues and failures. Let's start with the most
common issue we hear about, which is stiction. We have all heard the term stiction,
but maybe you don’t know what it means. Hot Shot’s Secret explains it best.
“Stiction is the sticky, gummy residue of burnt oil on moving engine parts that
cause dragging friction”. Have you ever had a 7.3 or 6.0 Powerstroke that was hard
to start when cold and even after started it was just really weak and slow to rev, but
after coming up to operating temp it starts to rev faster and run smoother? If so
that’s stiction. It will build up on the poppet and not allow it to move freely. This
usually happens when a lower quality oil and high oil temps meet. Throw all of that
on top of it being 10,000 miles since your last oil change and it’s a recipe for
stiction. Over time it is going to happen to any HEUI injector, but there are a few
things you can do to help combat it and keep your injectors healthy as long as
possible. Always use premium engine oil and change it at the manufacturer's
recommended service interval. We recommend Schaeffer’s 15w40 in the 7.3's and
follow that up with a quality Motorcraft oil filter.
Most of the other issues we see all involve the fuel side. Fuel contamination is a big
one, and the most common culprits are air, water, and trash. We have seen many
sets over the years come in with the complaint of white smoke. One of the most
common causes is the customer has gotten some dirty fuel and those particles and
debris have made their way past the fuel filter and into the injector/s. We usually
find that a piece of debris has gotten trapped between the pintle and the nozzle not
allowing it to close all the way. When that happens fuel is constantly dribbling into
the cylinder creating that white raw fuel smoke we all hate to see. Periodically we
get a set in that one or more nozzles have cracked or split. What we have found to
be the cause is a drop in fuel pressure or water in the fuel. When the nozzle spring
slams the pintle back shut it relies on the diesel fuel in the nozzle to cushion the
blow. When the diesel is replaced with air or water it does not provide an adequate
cushion for the pintle to seat back into the nozzle. This can also cause damage to
the pintle and nozzle seat allowing that same dreaded white smoke. Most of these
issues can be resolved by installing a fuel system with a quality water separator and
fuel filter.
Moving on to our last common issue, install error. Time and time again we get sets
of injectors sent back to us that have 1 or more blown copper sealing washers.
What causes this is the injector not being fully seated and torqued down in the cup.
When this happens the copper sealing washer cannot seal off the hot, sooty
compression gas from getting into the fuel side of the injector. Once that seal has
been compromised it will allow compression gas to aerate that bank of fuel
injectors, and allow that nasty soot and carbon to work its way into the fuel side of
the injector/s. If ran long enough with a blown copper it can damage the nozzle from
excessive heat, and soot contamination. If you do happen to have a blown copper
washer that is not something that is covered under warranty. So make sure you
have a quality shop install your injectors. If you have any questions regarding your
7.3 Powerstroke injectors feel free to give us a call. We are always available to chat
and have a knowledgeable staff that is here to help.