The high-pressure oil pump, or HPOP, is the heart of the HEUI injection system on the 7.3L and 6.0L Power Stroke, generating the oil pressure that actually fires the injectors.
What it does
Unlike common-rail engines that use fuel pressure to fire injectors, HEUI engines use high-pressure oil. The HPOP builds that pressure, and the IPR regulates it. Without adequate HPOP output, the injectors cannot open properly and the engine will not start or run correctly.
Signs it is failing
- Hard starting, worse when hot
- Extended crank and rough running
- Low injection control pressure readings
- No-start when pressure cannot build
Replacement and what to know
A worn HPOP that cannot build volume is rebuilt or replaced. Because leaks elsewhere in the high-pressure oil system mimic a weak pump, diagnosis should confirm the pump is the actual cause by reading injection control pressure and checking for leaks at fittings and O-rings.
Frequently asked questions
What does an HPOP do?
It generates the high-pressure oil that fires the injectors on HEUI diesels like the 7.3L and 6.0L Power Stroke.
How is it different from a fuel pump?
It pressurizes oil, not fuel. The oil actuates the injectors; fuel is delivered separately.
What are signs of a failing HPOP?
Hard hot starts, long crank, low injection control pressure, and no-start when the pump cannot build pressure.
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