ISX running on one bank

[Rawze]

(07-07-2016 )manolumber Wrote:  Thanks for the quick replies guys, much appreciated.
Checking grounds is always a good suggestion. I`m assuming the rear bank grounds at the same location as the front bank? If that is the case, the rear bank is functioning properly so ground must be good, right?
Havnt checked fuel pressure but I would think the ECM would set a code if low enough to starve one bank? If the fuel pressure was low wouldnt that affect both banks? I will check today as that was one of the checks I planned to do. Operating pressure should be about 250 psi, correct?
Wholesale changing of parts is not something I ever do. Initially I swapped the front and rear actuators and the issue stayed in the front bank. I also did an injector check valve test, both via Insite and manually, on the front bank and all checked OK. But there is alot going on in those injectors so in spite of not picking something up visually on inspection it was decided to go ahead and replace them. The downtime for this employer is as important as the cost of replacement parts, a little different mindset than an owner/operator. I am more conservative re the cost and I pride myself in being a good mechanic but the bottom line is the employer is paying me and he owns the truck. I will hold on to the parts and use them for future troubleshooting/repair as we have quite a few of these ISX`s so the money will eventually be recovered.
If I use a DVOM at the fuel actuator connector on a good known engine the DVOM shows a steady 5 to 6 volts while running. I assume the ECM is firing the actuator so quickly it translates into what appears to be a constant reading. When I do the same check on the problem vehicle I get the same readings.
I`m very suspect of the wiring to the front fuel actuator as the ECM displays a code for same every once in a while. Perhaps the wiring is hanging on by a strand or two resulting in good continuity tests but cannot carry the current necessary to cycle the actuator? I`m considering bypassing the circuit with an overlay harness, only 2 wires from ECM to actuator.
By checking combustion gas in the fuel system I`m assuming you mean thru the injectors or cups? I did a "bubble test" at the actuator and there was no indication of air in the fuel circuit. Any idea how I could isolate the head/fuel block to check for a crack or obstruction?
Thanks again for the help and suggestions. This one has me chasing my tail!

The test I was referring to was this one...





sounds like you are on the right trail with it to say the least,.

So at the end of the day...

If the fuel pressure it idle is good (above 260psi if memory serves me right) and ...

If swapping all of the hard parts (all 3 injectors + timing actuator + metering actuator) to the other bank does NOT move the problem...

(Checking the ECM/coils) ...
PUT an o-scope on a tightly wound coil of small wire, (about 8 or so turns is all the is needed) round a small nail. Hold the end of it up against the center of each of the metering and timing actuators one at a time while engine is running. See the coils are firing, and how strong they are firing. You can see if one of the coils is not firing correctly or is weak, etc.

AND/OR Replacing the ecm with a known good one.. (certified OEM reman or from another truck that will run without the issue) and NOT an ecm from some used garbage non-oem shop ecm repair trash place... but myself, I would still do the coil check with an o-scope mentioned above just to be sure. The ecm is sometimes known to fail those coils sometimes, but throw no faults.. and not tell you that it is refusing to fire them. It is a known bug in the ecm software... and also WHY you cannot unplug and re-plug the actuators to test them.
here is some info on this: http://rawze.com/forums/showthread.php?t...4#pid41924

I.E.> it is confirmed 100% that it is not any of those components, then...

If the engine is not running on one of its banks (front 3 or back 3 in total) and it stays on that same bank with ALL the components changed... + ecm is confirmed to be firing the solenoids correctly (via an o-scope) ... then ...

.. then it is simply starving for fuel for one reason or another.

Could be the diaphragms on the back side of the IFSM.. or a clogged passageway in the IFSM or thru the head past the solenoids.. .. OR .. a cracked head, maybe a failed injector o-ring,.. etc... something ... and its loosing fuel pressure internal to the head.

.. keep us informed as to what you find. it will certainly help others on here in the end.