X15 2250SN fault code 1911

[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.