The HEUI fuel injection system (Hydraulic Electronic Unit Injector) is different from electronic High-Pressure Common Rail system, Electronic Unit Injector system and Electronic Unit Pump system.
HEUI system is a hydraulically driven, electronically controlled fuel injection system developed by C-aterpillar and widely used in a variety of diesel engines.
To test HEUI injector, must need a professional HEUI Injector Test Bench.
| Maker | HEUI Injector Model |
| C-aterpillar | C7, C9, C-9, C3126, 3412E,3412A |
| ISUZU | TROOPER 4JX1 |
| NAVISTAR | DT466E |
| FORD | Ford G2.8 / Ford G2.9 |