HEUI Fuel Injection Failure and Solution

• Engines prone to stiction issues are the PowerStroke 7.3 engine from 1994 to 2003, the 6.0 from 2003 to 2007, the Navistar T444E and especially the VT365 which was manufactured from 2003 to 2007.

• Q:What is stiction?• A:A conjunctive form of Static Friction

• As it relates to injectors, it is simply pistons which stick in their bore, to a level which retards the initial movement.

The Documented Problem

• The 6.0L runs the high pressure engine oil system much higher than it was in 7.3 L PowerStrokes

• “4000 psi” causes shearing of oil polymers reducing a 15W40 viscosity oil to a 30 weight in as little as 1,000 miles

• Can result in increased exposure to wear because of reduced lubrication protection

• Contains extreme high-pressure engine oil system

• High-pressured oil pump is used - HPOP

• Pump used to pressurize the fuel within the fuel injector for proper atomization and direct injection into the cylinders

6.0L Facts

• Fuel injector "spool valve" is trying to move back and forth inside the injector

• In a 6.0L this is achieved with two 48v coils on each end of the spool valve while trying to overcome anywhere from 500-4000 psi oil pressures being generated

• Spool valve bore needs to be contaminate free and unrestricted for proper fuel injector operation

• Carbon contaminates, Varnish build up, or Wear will cause the spool valve to stick, especially when the oil is cold & thicker and isn't flowing as easily, even with thinner grade oils

In Summary…

Fuel Management System

There are injector stiction issues on Ford 6.0L & 7.3L PowerStrokes with the HEUI fuel injection system. (Hydraulic Electronic Unit Injection)

What is HEUI fuel injection?

• An engine oil pressurized fuel injection system

• Uses crankcase motor oil to pressurize the fuel inside the fuel injector via a separate high-pressure oil pump within the engine.

• High-pressure oil pump puts out anywhere from 500-4000psi oil pressure 

•Very hard on any motor oil, synthetic or conventional

Questions

What are the symptoms of fuel injector stiction?

• Romping uneven engine idle

• Hard starting & Cylinder misfiring

• Unable to accelerate until the engine warms up

• Loss of performance means lower MPG

Questions

What causes fuel injector stiction?

An inability for the high-pressurized motor oil to flow correctly through the fuel injector

1. "stiction" comes from sticking spool valves inside the fuel injector’s high-pressure oil circuitry

2. The spool valve allows oil pressure in and out of the fuel injector

3. It is controlled by two 48v coils inside the injector and moves side to side back and forth.

4. When ON, it allows oil pressure to push the fuel into the cylinders.

5. When OFF, it bypasses the oil back to the crankcase.

Questions

What causes these spool valves to stick?

Worn spool valves and or engine oil contaminates within the spool valve bore or orifice and varnish build up

• Spool valve only moves 0.43mm in a 6.0L PowerStroke

• Less than a half a millimeter for high-pressurizedmotor oil to flow

Questions

What can be done about the spool valves sticking?

Add Archoil AR9100 into your motor oil

-This will liquefy all deposits in the fluid systemfree up contaminated injector spool valves

-Injector stiction symptoms completely disappear, even at -20F

-Normally happens shortly after application

-If spool valves are severely worn or injectors have worn fuel delivery pintles or nozzles, it usually indicates injector needs replacing

AR9100 has a high 90%+ success rate, but it also does much more.

Answer

For more information go toArchoil.com

Contributing Technician

Harry Johnson

Mercedes Benz USA master certified diagnostic technician

ASE master and L1 certified advanced engine performance specialist

WA State certified diesel emission specialist