Oil pressure is everything for a 7.3L. One of the most common questions we get asked is related to how to test the High Pressure Oil Pump (HPOP) on a 7.3L Powerstroke. We say related to, because the high pressure oil system isn’t composed of just the HPOP. There’s more that comes into play to give the 7.3 the oil it needs. Insufficient high-pressure oil related codes most commonly come from a contaminated ICP (Injection Control Pressure) sensor, however, failed injector O-rings, low-pressure oil supply issues, HPOP failures, or even internal bypass regulators, amongst other factors, can come into play. Again, those are rare, and ICP contamination is hands down the most common. For this discussion, we’ll focus mostly on testing the HPOP.

How It Works: To understand how to test the system, we need to quickly discuss how it works.
The LPOP (Low Pressure Oil Pump) takes a supply of oil directly from the pan and sends it to, amongst other things, the HPOP. The HPOP then pressurizes the oil to between 500 and 3000 psi during normal operation. The amount of pressure needed is decided by the powertrain control module (PCM) and controlled by the injection pressure regulator (IPR) valve. The IPR valve keeps oil pressure as demanded by bleeding off pressure back into the pan or by closing up and sending it to the injectors. The valve simply moderates the oil volume needed to maintain that desired pressure. Once the injectors are done with the oil, they vent it from the top of each injector, under the valve covers, and onto the rockers. From there the oil returns to the pan to repeat the cycle.

Testing: There’s a couple ways to test the HPOP but they all involve watching Injection Control Pressure, or ICP. First, with a scan tool.

Scan Tool: While there are many different tests that can be done with a scanner, this specific test will give you a decent idea of how the system overall is working, and if it’s able to keep up with demand. We’ll cover how to test the HPOP on it’s own, without any other factors, next.
First, you’ll need a good scan tool; not all will show sensor readouts in real-time, which is what we need here. We prefer to use AutoEnginuity (found here: LINK) or Forscan. Whichever scanner you use, the first step is plugging the scanner into the OBD2 port under the dash. Next open your scanners live data viewing section and look for the ICP sensor readout (ICP is how we watch the pressure the HPOP is sending to your injectors). Then select DC% (IPR Duty Cycle Percentage) to monitor what the PCM is requesting. Then, it’s time to start the truck and go for a drive. Find yourself a road where you can run wide-open throttle for ten seconds or so. While watching ICP on the scanner, floor the accelerator. ICP will first spike and then start to drop off as it loses the ability to maintain peak pressure. This drop is normal, what we’re looking for is where it settles. As we said, the HPOP can make as high as 3000 psi under normal operation, but you only need to maintain around 2400 at WOT for the engine to run correctly.

Mechanical Gauge: This is the only way to test the HPOP on its own to determine if you have a bad HPOP or if it is something else in the High Pressure Oil system. For this test we’ll tap a mechanical gauge directly into the high pressure oil system. We’ll be using our HPOP Test Gauge found here LINK. We will also need an STC Quick Connect Male Cap (found here: LINK) to deadhead the system. More on this in a bit.
With the engine turned off, disconnect your HPOP lines from the heads. You’ll need a specialty tool to remove the HPOP lines, which can be found here: LINK. Once one line is removed, install the HPOP gauge on one line, and the STC Quick Connect Male Cap on the other line. The cap will eliminate any oil leaking from that line and is necessary to “deadhead” the system. Deadheading the system means the pump will make pressure, but it won’t go anywhere, allowing us to monitor peak pressure. After this is done, it’s time to take the IPR valve out of the picture. Remove the IPR and replace it with our HPOP IPR Block Off Test Tool (found here: LINK). The pump is now completely disconnected from the system other than the LPOP supply to it. Now, onto testing.
Have someone crank the engine over while you watch the gauge from under the hood. In this test, we’re not looking for pressure readings after it settles like we did with the scanner; we’re looking for a consistent pressure output. The 7.3L’s HPOP, when the engine is running, supplies between 500 and 3000 psi, as we noted before; however, it is capable of 4000 psi when deadheaded. The volume it puts out simply won’t keep up with its max pressure of 4000 psi when the injectors are running, which is completely normal. But, even though the pump is designed to make 4000 psi, 4000 psi is not common to see when doing this test.
So, if you’re seeing around 2000 psi or more, your HPOP is very likely in excellent condition, and any issues you have would be from somewhere else in the system. The most likely culprit being the IPR valve, but not necessarily because it has failed. It’s more likely just contaminated and needs to be cleaned.

Side note: To test whether the HPOP is receiving a sufficient supply of oil from the LPOP, a gauge can be installed on top of the HPOP reservoir via its fill port to monitor pressure. Above 7 psi at idle will show as normal on your dash gauge cluster; however, 12 psi is the Ford spec for normal operation.

***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.