X15 2250SN fault code 1911

[Kenworth509]

Hey guys I’ve got a X15 2250SN with a fault code 1911, engine is no deleted or any modifications with calterm.
I’ve done extensive testing of fuel components and still no luck, the rail pressure fluctuates at idle from 9500psi-5900psi while command pressure is 7200psi. Once you shut it off it will maintain rail pressure but it’s up from anywhere from 8500psi to 10500psi while command is still 7200psi.
When driving in high rpm the rail pressure gets to 42000psi and you back off the throttle and the rail will just hold that high pressure anywhere between 27000psi to 42000psi while command is right down around 7200psi
I’ve inspected all fuel pump components and even ran another fuel pump head and actuator and still faults, no air is present in the system when hot or cold, replaced rail pressure sensor, rail relief valve.
I’ve done a fuel pump performance test all ok at 175ml over 30 seconds cranking at 130rpm.
I’ve done an injector return flow test and over the 60 seconds only 40ml is measured. Quickserve only list a maximum injector return flow and nothing about minimum.
It also passed an injector performance test but I’m starting to think there is an issue with the injectors possibly.
I’ve also swapped ECMs and tried different cummins calibrations just to cancel out the electrical side of things, engine harness is fine as well with pin out testing all ok.

If anyone has any handy info or can help let me know Thankyou.

[tree98]

This code doesn't appear to be associated with the X15 so I'm assuming you have a cm2250?? Not sure what you mean by "SN"

Anyway, according to quickserve that 1911 code is triggered when the ECM sees the fuel rail pressure relief valve is open but no fuel pump actuator circuit error is present.

The following is copied directly from quickserve

***********Purging air through the fuel system can cause a pressure overshoot, therefore causing Fault Code 1911 to log. A few bubbles exiting the line during the air in fuel test is expected. A foamy appearance is an indication of a leak that allows air to enter, a severe inlet restriction that causes cavitation, or a system that is not yet primed. If fuel inlet restriction is not excessive, the source of air entry should be isolated to one of the following: Suction fuel lines, OEM fuel lines, suction-side fuel filter assemblies, or stand-pipe(s) in the fuel tank(s).

Sustained periods of very low pressure under load followed by pressure recovery overshoot. This can be caused by high restriction due to plugged filters (Fault Code 559).

A tampered fuel pressure sensor that reads low, a biased pressure sensor, or a poor electrical connection.

If an intermittent electrical circuit problem with the fuel pump actuator circuit exists, it is possible for Fault Code 1911 to become active, then inactive, during normal engine operation. ECM Fault Code 2311 is designed to detect electrical circuit issues with the actuator. Therefore, it is only necessary to inspect for bad connectors or harness issues for Fault Code 1911 if no other fault codes exist. A fuel pump actuator with excessive leakage will result in high rail fuel pressures at idle or light load.

Other conditions include ECM wiring harness issues such as poor grounds, battery voltage spikes, electrical noise, low alternator output, and large disturbances of battery voltage, as when jump-starting the vehicle.

The fuel rail pressure sensor should also be checked. When checking the fuel rail pressure sensor accuracy, make sure the high-pressure fuel rail is not pressurized. The fuel pump, high-pressure fuel lines, and fuel rail contain very high-pressure fuel. Do not loosen any fittings while the engine is operating. Wait at least 10 minutes after shutting down the engine before loosening any fittings in the high-pressure fuel system to allow pressure to decrease to a lower level. There could be a significant amount of time waiting on the rail to depressurize to zero on some engines. In such cases, it may be necessary to manually relieve the pressure from the high-pressure fuel rail.**********

You say you've checked all these things but you must have missed something.

[Rawze]

(03-04-2023 )Kenworth509 Wrote:  Hey guys I’ve got a X15 2250SN with a fault code 1911, engine is no deleted or any modifications with calterm.
I’ve done extensive testing of fuel components and still no luck, the rail pressure fluctuates at idle from 9500psi-5900psi while command pressure is 7200psi. Once you shut it off it will maintain rail pressure but it’s up from anywhere from 8500psi to 10500psi while command is still 7200psi.
When driving in high rpm the rail pressure gets to 42000psi and you back off the throttle and the rail will just hold that high pressure anywhere between 27000psi to 42000psi while command is right down around 7200psi
...

There is only one way to test the fuel rail for leaks.. and it is not at 7200 psi.. or at idle pressures. Many of the internal fuel system leaks will not show up at this low of pressures.

It has to be done exactly like this video shows ... at 29,000+ psi..


https://www.bitchute.com/video/LyC8kZ1FKdd4/

[Kenworth509]

Thankyou for your replies, yes it’s a cm2250sn, it’s the Aussie cm2250. I have access to quickserve and have gone through all fuel system diagnostic tests, yes I have done the high rail pressure leak test as per quickserve and your video Rawze.
There are no internal fuel leaks, this is why it has stumped me on this one.
I have all the cummins fuel system testing tooling for these XPI systems.

[Rawze]

(03-05-2023 )Kenworth509 Wrote:  Thankyou for your replies, yes it’s a cm2250sn, it’s the Aussie cm2250. I have access to quickserve and have gone through all fuel system diagnostic tests, yes I have done the high rail pressure leak test as per quickserve and your video Rawze.
There are no internal fuel leaks, this is why it has stumped me on this one.
I have all the cummins fuel system testing tooling for these XPI systems.

Then the next test is to see how much fuel is going back to the return lines. I think cummins has a test for this to see if there is too much being returned. I think that fault is associated with that if
I am not mistaken.

[Kenworth509]

On quickserve cummins only give a maximum spec of 200ml of 60 seconds for injector return measured from the return block.
This test is carried out with insite using the high pressure fuel leakage test and then you take the measurement. I’ve always had a constant injector return flow from previous jobs.
But this engine is returning only 30-40ml of the 60 second time period witch has me thinking it isn’t enough.
I’m installing a new X15 this week coming into another truck so once it’s installed I will do some return testing on that and compare.

When you drive this truck with the faulting fuel system and it becomes active you loose the pedal as described in quickserve because the ecm has put the fue actuator in reset, and you watch the fuel rail pressure disappear as the relief valve is working correctly. You then shut the engine off and you can hear the relief manually reset.

[Rawze]

Sounds to me like it is getting air in the fuel somewhere then.. if all else is checking out good and you replaced so many things.



Also Check the inside bottom of the fuel tanks to see if there is a layer of coolant or water down in the bottom, below the fuel, with a bright flashlight.

[Kenworth509]

Well that’s what it seems but I’ve checked for air while the engine is cold and at operating temp and it’s a solid stream of fuel with no air present at all.
I will check that out when I get back to it in a weeks time. I have checked the filters and no coolant seems be be present in them either.
Il let you know once get back to it and check it out mate.

[Rawze]

Maybe also try pulling the manifold away from the head a bit by removing all (only) the manifold stand-off's from the bolts + loosen everything up a bit .. so that there is a tiny gap to the head ... and then crank it after letting it sit over night to cool off. See if one of the cylinders is spitting fuel (or oil) and wet stacking at first crank.