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​What Does a High Pressure Oil Pump Do?

Oct 5th 2021

engine fuel injection nozzle

A high pressure oil pump (HPOP) is a crucial part of the Powerstroke engine. Just like the name implies, it is a high pressure pump that sends oil to other parts of the engine, which provides lubrication. Older versions of the Powerstroke engine utilized what’s known as a HEUI system, which stands for a hydraulically activated, electronically controlled, unit injector fuel system. This technology is considered outdated by today’s standards, but many vehicles on the road still use this process.

The HPOP helps the HEUI system do its job in more ways than one. Learn more about high pressure oil pumps and how they keep your engine running.

Using a High Pressure Oil Pump

Unlike conventional pump systems, the HPOP doesn’t create pressure through traditional means. Pressure is based on how much oil the pump is sending through the pistons. Many HPOPs have seven pistons as part of a swashplate-style pump. The location and functionality of the pump depend on the manufacturer.

For example, the Bosch high-pressure oil pump is gear driven and works with a 7.3L Powerstroke engine. It is externally mounted to the front cover at the front of the lifter valley. The drive gear isn’t timed to the cam or the pump.

However, a Siemens high-pressure oil pump sits in the crankcase at the rear of the 6.0L Powerstroke engine. It’s timed to the engine itself.

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The HPOP works in tandem with other components. It’s a part of a closed-loop injection control system that involves the Powertrain control module, injection pressure regulator, and the injection control pressure sensor.

The PCM is calibrated based on programmable inputs. It controls the injection pressure regulator, which regulates the amount of oil coming through the high pressure oil pump, usually with a range of 500 to 4,000 PSI. As the HPOP releases oil into the pistons, the injection control pressure sensor monitors the flow. It will then signal back to the PCM to make sure everything is working correctly.

car engine

The Injector Firing Process

When the injectors are getting ready to fire, the electronic solenoid gets energized by the injector drive module (IDM). This pulls the poppet valve off its seat, which closes the oil drain pathway, making way for high-pressure oil.

The oil will then transfer its pressure through the poppet valve, located on top of the intensifier piston. The intensifier piston has seven times more surface area than the plunger, which means high-pressure oil with 3,000 PSI injection control pressure will convert to 21,000 PSI of fuel injection pressure as it enters the combustion chamber. After market injectors with large plungers can help reduce the multiplying force of the intensifier piston.

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The high-pressure oil on the intensifier piston will then force the plunger down, which raises the nozzle needle. The fuel is then pressurized in the plunger cavity. The nozzle is then opened, sending fuel into the combustion chamber. The nozzle is similar to other nozzles except that it uses a check ball to seal the plunger during the downstroke, which prevents fuel from leaking out.

As the intensifier piston and plunger stroke downward, the void at the top of the injector is filled with high-pressure oil that’s been waiting in the oil rails. The injection pressure regulator valve and HPOP move the oil once the pistons have fired.

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high pressure oil pump

Problems with the HPOP

If the high-pressure oil pump isn’t working properly, you may notice a burning smell under the hood. Oil may also be leaking out of your exhaust, creating what looks like blue smoke.

The HPOP is designed to last forever but it will lose its power over time. If you notice some of these problems or the engine is starting, there may also be a problem with the IPR valve.

Keep these tips in mind as you get more comfortable working on or with your high-pressure oil pump. Every driver should be familiar with this crucial component and how it feeds high pressure oil to other parts of the engine.

If you need a new high-pressure oil pump or IPR valve, replace them before the problem gets any worse.

Image Credits:

MR.TEERASAK KHEMNGERN/Shutterstock.com