How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site.
    Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask ][\][iCk0411 Your Own Question
][\][iCk0411, Fleet Manager
Category: Medium and Heavy Trucks
Satisfied Customers: 69
Experience:  310T Red Seal- Truck and Coach Technician
Type Your Medium and Heavy Trucks Question Here...
][\][iCk0411 is online now
A new question is answered every 9 seconds

I have a isx cummins running very rough. Cummins Insite

Customer Question

I have a isx cummins running very rough. Cummins Insite shows cylinder number 3 to be over fueling. Truck has lots of black smoke. Have replaced all timing and metering solenoids also replaced number 3 injector with no change in performace
Submitted: 7 months ago.
Category: Medium and Heavy Trucks
Expert:  ][\][iCk0411 replied 7 months ago.

Welcome to Just Answer. My Name is ***** ***** I can help you today. I just wanted to start with some questions.

After all the work performed is the #3 over fuel happening as an active code?

Is there any other active or inactive codes?


Customer: replied 7 months ago.
No codes. Cummins Insite shows cylinder 3 over fueling while doing the cylinder performance test
Expert:  ][\][iCk0411 replied 7 months ago.

When you installed the injector, how did the valve assemblies seem? I'm assuming you did a valve adjustment once the injector was installed, did it need any adjustments out of the ordinary that would suggest hat there is a valve, or cam wear issue?

So it has the same symptoms as before the repairs are completed? Better, worse? Anything different between now and then?

Have you been able to physically identify that its only over-fueling in #3? I only ask because it everything else checks out and its still the only cylinder then I'm wondering if it is a faulty injector that was installed? I've seen numerous times some issues related to defective injectors.

Let me know your thoughts.

Customer: replied 7 months ago.
Valves were in adjustment. Also thought I may have gotten a faulty injector but I switched number 2 and 3 and over fuel condition stayed with cylinder 3. Cylinder performace test shows only number 3 to be over fueling
Expert:  ][\][iCk0411 replied 7 months ago.

Okay well that's great that the Fuel injector is ruled out for sure then. That tells me it could be two other things so I would recommend, if possible, to take a look inside that cylinder.

I use one of the small camera tools sold by any of the popular tool dealers. You can enter the cylinder easily through the intake manifold, that way you don't have to tear the motor down. I'm concerned that there could be something wrong in the cylinder that is causing that code such as damaged, leaking valves, or piston rings wiping oil into the cylinder? Should be easy to tell once inside the cylinder whether its wet with oil or fuel to confirm.

since you had the top end apart I am thinking you didn't see anything out of the ordinary when you had the top end apart like worn cams or valving? If the fuel isn't over fueling my thought is that could the control side of the injector be causing an over fuel?

If all this checks out and your confident its over-fueling then I would be looking to inspect the injector cup area for cracks. I'm not sure if your head would have a serviceable cup, but I have seen the heads crack before.

Let me know what your thoughts are and whether you have any other questions. This sounds like a bit of a tough issue so I hope I am lending some help.


Related Medium and Heavy Trucks Questions