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Diesel truck engines have occasional mechanical issues due to poor maintenance or faulty components. One major failure with diesel engines occurs in the fuel delivery system. One of the culprits can be fuel injectors.

We came across common fuel injector issues with a 2001 Chevy Silverado Duramax 6.6L (LB7, 2001-2004) turbo. The engine was overheating, had a rough idle and suffered from poor acceleration. The vehicle was taken to a shop for diagnosis. A fuel injector problem was quickly detected after an On Board Diagnostic (OBD) II diesel scanner was connected to the OBD II port under the dash.

Fuel injectors can fail due to clogging, poor flow rate, faulty spray pattern, leaking or electrical issues. To further detect the problem, all of the fuel injectors were removed and sent out to tested. After testing all eight injectors, five were determined to be bad. The five bad injectors were thoroughly cleaned, examined, rebuilt and then re-installed. Unfortunately, after driving the vehicle for a couple hundred miles, the injector housing started leaking fuel into the oil. Of course, this was disturbing for the owner after spending time and money trying to solve the problem.

1. To eliminate fuel leaking into the oil, it was decided to replace all of the OEM fuel injectors with new Bosch injectors.

1. To eliminate fuel leaking into the oil, it was decided to replace all of the OEM fuel injectors with new Bosch injectors.

2. After disconnecting the negative battery cable, the electrical connectors were removed from the main wiring harness, along with the electrical connector from the barometric sensor.

2. After disconnecting the negative battery cable, the electrical connectors were removed from the main wiring harness, along with the electrical connector from the barometric sensor.

3. The main fuel line (bottom larger) and return-line (top smaller) need to be disconnected from the bulkhead. A special tool is required here.

3. The main fuel line (bottom larger) and return-line (top smaller) need to be disconnected from the bulkhead. A special tool is required here.

To ensure proper detection, testing, repair and installation make sure you go to a certified professional diesel shop. Replacing injectors is best done by an experienced professional—let the buyer beware!

This Silverado was delivered to a very dependable diesel shop—Domestic Diesel in Chino, California—where John Ferguson and his crew examined the Duramax 6.6L fuel injection system. After pulling the oil dipstick, you could smell the diesel fuel in the oil. It was determined that to cure the fuel leaking into the oil it would be best to replace all eight, injectors with new Bosch (PN0986435502 #19) fuel injectors.

Follow along as Domestic Diesel’s Chris Greenberg properly removed and installed all-new Bosch fuel injectors. The results were immediate and the owner was ecstatic. DW

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4. A 19mm open wrench was used to loosen the fuel injection lines from the fuel rail and fuel injectors. The upper fitting on the line is done first.

4. A 19mm open wrench was used to loosen the fuel injection lines from the fuel rail and fuel injectors. The upper fitting on the line is done first.

5. After removing the fuel lines from the injectors and fuel rail, a 10mm socket was used to remove the top valve cover bolts from the bottom valve cover base.

5. After removing the fuel lines from the injectors and fuel rail, a 10mm socket was used to remove the top valve cover bolts from the bottom valve cover base.

6. The OEM bare fuel rail was then inspected for bad threads, debris or nicked seat surfaces.

7. The injector solenoid wires were removed using a 7mm socket.

7. The injector solenoid wires were removed using a 7mm socket.

8. A 5mm Allen socket was used to loosen and carefully remove the fuel return line.

8. A 5mm Allen socket was used to loosen and carefully remove the fuel return line.

9. A special Kent Moore (PNJ11639) injector-extracting tool was used to correctly unseat the injectors from their bores. This tool will eliminate damaging the injector during removal.

9. A special Kent Moore (PNJ11639) injector-extracting tool was used to correctly unseat the injectors from their bores. This tool will eliminate damaging the injector during removal.

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10/11. The Kent Moore injector-extracting tool was secured to the injector, which was loosened and then lifted out of the injector bore.

10/11. The Kent Moore injector-extracting tool was secured to the injector, which was loosened and then lifted out of the injector bore.

12. This image shows the old injector (left) and new Bosch injector (right). Quality is not always visible at first glance, but it’s seen in engine performance right away. Don’t skimp here; all replacement injectors are not the same, as this owner found out the first time around.

12. This image shows the old injector (left) and new Bosch injector (right). Quality is not always visible at first glance, but it’s seen in engine performance right away. Don’t skimp here; all replacement injectors are not the same, as this owner found out the first time around.

13. Before installing the new Bosch injectors, Greenberg applied grease to the nozzle copper seal washer and oil to the oil ring seal.

13. Before installing the new Bosch injectors, Greenberg applied grease to the nozzle copper seal washer and oil to the oil ring seal.

14. All new seals were also installed to the fuel return line.

14. All new seals were also installed to the fuel return line.

15. The fuel return line was carefully installed and secured using a 5mm Allen socket.

15. The fuel return line was carefully installed and secured using a 5mm Allen socket.

16. Before installing the bottom valve cover, the base rubber gasket was glued into position and allowed time to cure before being installed to the head surface.

16. Before installing the bottom valve cover, the base rubber gasket was glued into position and allowed time to cure before being installed to the head surface.

17. After aligning the bottom valve cover base, the bolts were then secured using a 10mm socket.

17. After aligning the bottom valve cover base, the bolts were then secured using a 10mm socket.

18. The injector solenoid harness wire leads were then connected to the solenoid terminal posts and secured using a 7mm socket.

18. The injector solenoid harness wire leads were then connected to the solenoid terminal posts and secured using a 7mm socket.

19. Greenberg carefully applied silicone to the upper valve cover mounting surface for a tight seal.

19. Greenberg carefully applied silicone to the upper valve cover mounting surface for a tight seal.

20. After the silicone was given some time to cure, the top valve cover was then aligned and secured using a 10mm socket.

20. After the silicone was given some time to cure, the top valve cover was then aligned and secured using a 10mm socket.

21. The appropriate injector fuel lines were carefully aligned and the fittings were then threaded first by hand to eliminate possible cross threading.

21. The appropriate injector fuel lines were carefully aligned and the fittings were then threaded first by hand to eliminate possible cross threading.

22. A 19mm open wrench was used to snug up and tighten the fuel line fittings. Always start tightening the fuel line from the injector side first, and then the fuel rail fittings.

22. A 19mm open wrench was used to snug up and tighten the fuel line fittings. Always start tightening the fuel line from the injector side first, and then the fuel rail fittings.

SOURCE:

Domestic Diesel

909.627.0500