Help!!! Cummins isx 500

First thing i would check is fuel pressure on DYNO (under load) at Cummins , as for bypass Davco and no more air in lines let me tell you a very strange thing , i had the same problem and i replaced not one but TWO davco in 2 weeks and all the 3 when bypassed resulted "no air in lines" ??? , strange crap , 3 DAVCO , two new and a old one can not be all bad , this issue will happen also when the "pickup fuel pump" is bypassed , no more air on lines ,...so they also changed the pickup fuel pump to fix this,....guess what , same problem even with the new pump !,...AFTER THIS I GAVE UP ON THIS ISSUE AND I DRIVE LIKE THIS ,...some guy told me that maybe a bad injector can push CO2 back in the lines ,..who knows.

At the end your issue can be just a bad DAVCO ! , but if you replace one and have same problem just don't listen to Cummins and replace the "pickup fuel pump" because you will not solve nothing.

The " FUEL SHOT-OFF SOLENOID" will restrict some 40% of fuel pressure and will drop boost to 20 downhill and when the truck decelerates , lots of black smoke when this happen, issue is intermittent .

 

The timing and metering Actuators on the IFSM can cause alot of grief however they are pretty expensive to replace all 4 .. They should also be doing a water monometer test to see if the injectors are faulty and pumping air in they system.

The turbo actuator should also be checked for range of motion/leaks and opening pressure.. also have a close look at the comp. and impeller wheels on the turbo for damage.check for any binding on the VGT shaft when its hot and cold.

It is very posible that the ecm could be causing issues as mentioned above..As well as Engine base timing..Make sure the latest and greatest calibration file is installed

Wouldnt be too concerned about head gasket unless you are pressureizing or burning coolant.

Excessive Black smoke is usually an egr valve on this engine,turbos fail very regularly moreso on 2007 engines and up though. Boost pressure/temp sensor and exhaust gas pressure sensors and pigtail are the most common sensor issues.

Charging system and Grounds have to be Pristine as well.

Hope this helps.. good luck , i know it can be frustrating and expensive...

Cheers

 

I have a used vgt turbo and actuator 40,000 50,000 miles on it sell both for 2,000 call 513 464 0404 Thanks RC moving on.



ALSO HAVE A PITTSBURG POWER BOX COST NEW 2,400 SELL FOR 1,500 FIRM THANKS RC MOVING ON.
THE BOX WILL GIVE YOUR TRUCK POWER .IF YOUR TRUCK IS AS SICK AS MINE WAS THIS BOX WILL INCREASE YOUR PULLING ON A LONG HILL TEN MILES PER HOUR. AND INCREASE YOUR FUEL MILEAGE.

 

I didnt see if u changed the turbo or if u fixed the issue.. but i had the same problem once my boss spent over 4k on everything else he found out the turbo was going out also my truck was doing the same thing as yours