Kubota V2403 Engine Guide: Problems, Cat C2.4 Crossover, and Replacement Options
07/21/2026
The classic sign of bad 6.0 Powerstroke injectors is stiction: a hard cold start followed by a rough, smoky idle that smooths out once the engine warms up. Add a dead miss, buck and surge, low power, and injector or FICM codes, and you have the 6.0L’s most common fuel complaint. This guide covers the symptoms, the critical 9/22/03 build-date split that decides which injector you need, and how the high-pressure oil pump (HPOP) can cause a no-start that looks exactly like bad injectors.
Why 6.0 injectors stick (“stiction”)
The 6.0L uses Bosch G2.8 HEUI injectors with an internal spool valve. Like the 7.3, they are fired by high-pressure engine oil. Over time and heat cycles the oil inside the injector varnishes, the spool valve sticks, and the injector is slow to respond — worst when everything is cold and the oil is thick. That is why the tell-tale 6.0 symptom is a hard cold start with a rough, hazy idle that clears as it warms. Contaminated or overdue oil accelerates it, which is why a strict oil-change discipline is the cheapest injector insurance on a 6.0.
Symptoms of failing 6.0 injectors
- Cold-start stiction — hard start, rough smoky idle cold, smooths out warm.
- Dead miss on one or more cylinders.
- Buck, surge, and low power, especially under light load.
- White smoke at idle from an unburned or partially firing cylinder.
- Injector or FICM codes; a cylinder that fails contribution testing.
These overlap with FICM, oil-pressure, and glow-plug issues — work the general diesel injector failure symptoms and cold-start checklists first so you replace the right thing.
The 9/22/03 split: which 6.0 injector do you need?
This is the one that trips people up. Ford revised the 6.0 injector partway through 2003, and the two are not interchangeable. Match by the build date on your door sticker:
| Alliant Power P/N | Build Date | Years |
|---|---|---|
| AP60900 | Built before 9/22/2003 | 2003–2004 (early) |
| AP60901 | Built on/after 9/22/2003 | 2003–2010 |
When it’s the HPOP, not the injectors
Because the G2.8 injectors are HEUI, a high-pressure oil problem can crank-no-start or run poorly exactly like bad injectors. Suspect the HPOP, IPR, or the notorious STC fitting when the truck won’t build injection control pressure (ICP) on cranking, has a long hot crank, or drops power with a pressure fault rather than a per-cylinder miss. If it can’t make oil pressure, injectors won’t fix it.
Why buy from Valley Fuel Injection
We have rebuilt and calibrated diesel fuel systems since 1993, we are Bosch-authorized, and we ship genuine Alliant Power 6.0 injectors and HPOPs nationwide with free UPS Ground to the lower 48. Tell us your build date and we will confirm the correct AP60900 or AP60901 set before you order — no guessing, no wrong-part returns. Browse all Ford Powerstroke injectors or call us with your VIN and build date.
Frequently asked questions
What are the symptoms of bad 6.0 Powerstroke injectors?
Cold-start stiction (hard start and a rough, smoky idle that clears once warm), a dead miss on one or more cylinders, buck and surge, low power, and injector or FICM codes. The 6.0 G2.8 injector uses a spool valve that sticks when the oil in it varnishes, which is why the classic symptom is worst on a cold start and improves as the engine warms.
What is the 9/22/03 injector change on the 6.0?
Ford revised the 6.0 injector during the 2003 model year. Trucks built before 9/22/2003 use the AP60900 injector; trucks built on or after 9/22/2003, through 2010, use the AP60901. Check the build date on the door sticker before ordering, because the two are not interchangeable.
Can a bad HPOP cause a 6.0 no-start?
Yes. The 6.0 injectors are HEUI, fired by high-pressure engine oil. If the HPOP, IPR, or the STC fitting cannot build or hold high-pressure oil, the truck will crank and not start, or start hard and run with low power. If you have low ICP on cranking, look at the high-pressure oil system before condemning injectors.
Should 6.0 injectors be replaced as a set?
For a stiction or age-related failure, yes, replace all eight as a set so the truck runs evenly and you are not back in the valley covers in six months. We sell 6.0 G2.8 injectors as reman sets of eight and as singles for a single failed hole.
