Bodacious Diesel |16051 W 4th AveGoldenCO80401 | (303) 808-1563
Bodacious Diesel
16051 W 4th Ave
GoldenCO 80401
 (303) 808-1563
Powered by: Renown Review Marketing

Fuel Injectors Failure and Diagnosis

Fuel Injectors Failure and Diagnosis

Diesel fuel injectors fail for many reasons, and some of those reasons are not always easily diagnosed. Even when you are able to hook a scan tool up to electronic injectors, you may have trouble diagnosing them — and that is because even electronic injectors could mechanically fail. While the scanner won't find a mechanical failure, it will tell you which cylinder is having issues. Sometimes an injector is just worn out, it may have a crack or it may even have injector stiction. When you keep up the maintenance on your diesel trucks, you have fewer problems with the injectors, but because of the moving parts, they will still wear out.


If a fuel injector is leaking, the engine may be hard to start, or your scanner will pick up low-pressure codes on the common rail. Injector leaks may be due to leaking cross-feed tubes on Cummins engines, worn fuel injector ball seats, incorrect nozzle needle clearance, a blown internal high-pressure seal or cracked nozzle body.

Improper Injection

The injection may be excessive, not enough or not happening at all. Indicators vary:

  • You may notice the exhaust smoking at idle, the engine running poorly or may hear banging if you have an excess injection. Balance rates may be high, the cylinder contribution test may show high, the exhaust gas temperature may be excessive or the engine may be damaged because of the excessive heat during rich conditions if the injector rate is too high.

Even when you are able to hook a scan tool up to electronic injectors, you may have trouble diagnosing them – and that is because even electronic injectors could mechanically fail.

  • If you are not getting any injection, the diagnostic could show high balance rates, low cylinder contribution and ECM fault codes.

  • If the engine is getting the injection, but the rate is incorrect, the engine will run rough and you will see a large variation in the temperature from cylinder to cylinder.

You may have worn injector ball seats, worn nozzle seats, debris holding the injector open or a cracked nozzle if the engine is getting too much fuel. If you are not getting any fuel, something could be blocking the injector nozzle or the armature or the nozzle needle is stuck. The stator could be bad, which is rare. This could also be a sign of a loss of compression in the cylinder or another mechanical problem.

With incorrect nozzle rates, you could have a poor nozzle flow balance or the nozzle needle lift is not correct. Additionally, you may have a partially plugged nozzle.

Preventing Problems

To prevent these problems, make sure the fuel filter is changed at the proper intervals, don't use portable construction fuel tanks, keep the entire fuel system lean and buy diesel fuel from reliable sources.

You should also avoid tuning the system so much that it increases the rail pressure and injector pulse widths. Never remove the pressure limiting devices from the fuel system. If you do have to replace any of the injector components, use the proper brand. Using aftermarket or remanufactured parts may cause the above issues. Ensure that the replacement parts do not have metal burrs.

Contact Bodacious Diesel

If you are having problems with the fuel injection in your truck, contact us at Bodacious Diesel to schedule an appointment for diagnosis and repair.

Does your diesel need repaired? Let us help! Contact us