2018 GMC Sierra Wont read fuel rail pressure sensor signal

Hello, I have a 2018 GMC Sierra 5.3 engine code C Gas with a 8 speed transmission. Check engine light and engine power reduced are turned on. Scanner shows 1 code, P228C, which says fuel pressure regulator 1 exceeds control limit - pressure too low. When i chech the live data you can see that the sensor does show pressure on the fuel rail, but the voltage on it remains at 0. This sensor also detects the fuel rail temperature and that is at -40. Truck turns on and idles but has little to no power. I checked the wiring and everything has continuity. I replaced the fuel rail pressure sensor, the high pressure fuel pump and the ecm and it does the same thing. The sensor is a 3 wire sensor. Both the ground and the 5v reference are good, but when it comes to the signal, the wire remains at almost 5v and the scanner shows it has 0v. Even with the sensor unplugged the scanner still shows the same 0v on the sensor and the pressure ready raises to 98,000 i believe. I cant remember the exact pressure but it rises a lot. Also the scanner says that the fuel rail pressure sensor hasn't been learned and thay learning is disabIed. I would appreciate any help with this issue, thanks!

The fuel rail pressure sensor transmits fuel pressure and temperature information by serial data using the Society of Automotive Engineers (SAE) J2716 Single Edge Nibble Transmission (SENT) protocol. The fuel rail pressure sensor internal microprocessor allows 4 separate sensor outputs from one 3 wire sensor. The ECM supplies the fuel rail pressure sensor with a 5 V reference circuit, a low reference circuit, and an asynchronous signal/serial data circuit. The asynchronous signal means communication is only going from the fuel rail pressure sensor to the ECM. The ECM decodes the serial data signal into separate voltages which are displayed on a scan tool as the voltage inputs from the Fuel Temperature Sensor, Fuel Rail Pressure Sensor and Fuel Rail Pressure Sensor 2.

Identifix testing procedure states the signal wire should have 5 volts with it disconnected.
Service info says an open, shorted to ground or shorted to voltage signal wire will show 95,058 PSI.  It also says the high pressure system is protected by a relief valve in the pump that prevents the pressure from exceeding 21.5 MPa (3,118 PSI). It stands to reason the pressure is not really going that high otherwise the pump relief valve would be screaming at you.

The fact that this PSI value changes when you unplug it and you don't have any codes for this fuel rail pressure/temperature sensor kinda makes me want to look away from it but it doesn't hurt to check it anyway.

Is the 361 PSI reporting vs the commanded 928 PSI real? Check this value in generic obd2, kill the low psi fuel pump and watch the engine die - does the 361 PSI drop down? I believe there's a command to depressurize the high side pressure as well you can use.

See static.nhtsa.gov/odi/tsbs/2019/MC-10162136-9999.pdf

A quick test to see if the fuel pressure sensor is the concern:

• Engine must be cold! 
• Set up GDS/MDI
• Navigate to Fuel System Depressurize
• Engine at idle – depressurize fuel system
• Fuel pressure sensor value should drop to Zero and engine will stall
• Suspect sensors will not drop to zero but rather the engine will stall and the sensor will still read 30-40 PSI

Note : If the engine is warm/hot heat will expand the fuel in the system causing the pressure to stay up. The engine will continue to run much longer and the sensor value will not go to zero.

You don't mention you have timing codes and service info says this pump runs off a 3 lobed cam so timing is important for this "internal solenoid-controlled valve." Was the cam lobe checked for damage? 

Thanks for your help! I did check the cam and the roller for the pump and they are both good. The timing on the engine is also good. I depresurized the system as you said and the fuel rail pressure sensor drops the pressure from wherever it is, to about 29psi and engine dies. When i was doind this test pressure was about 900psi but pluctuated quite a bit from 800-900. Also while doing this, temperature remained at -40 and voltage at 0v

If the fuel rail pressure is not to the computers liking at 25% Fuel Pressure Regulator High Control Circuit Command at 562 RPM and the cam and roller for the pump is good, is there a possibility of a leak on the high pressure fuel side? The difference between rail pressure desired and actual is 567 PSI. Could the high pressure fuel be leaking into the oil? How are your fuel trims at idle?

There is another test described in service info called the "Fuel System Pressure Test" which does the following: "This device control is used to charge the fuel rail on a high pressure direct injection system before completing the assembly of the engine in order to check for fuel leaks. This feature will allow the technician to inspect the fuel system for leaks after servicing the fuel system or after any other service procedure that required disconnection or removal of fuel system components. The starter relay is commanded on to crank the engine. Spark (SIDI) and fuel injection are inhibited to prevent the engine from starting. The high pressure fuel pump/regulator(s) are controlled to ensure maximum fuel system pressure is achieved while the engine is cranking and fuel pressure maintained after the engine stops rotating ."

We havent ran the truck a lot and we keep reseting everything after we do something to it so right now everything is as 0. Also the truck has long tube heaters without cats. I will see if the fuel system has any leaks. But almost everything is new. Ill check of the injectors are leaking, do you think that a fuel leak would cause the data from the sensor not to show? I will check the injectors since thats the only part of the high pressure system that hasnt been replaced

Christian9000 wrote:

 do you think that a fuel leak would cause the data from the sensor not to show?
 

I don't know why the fuel temperature is showing -40 degrees F because then it wouldn't run the P228C check if that was true.
 


Keeping it simple, the high pressure pump can't produce the high pressure or there's a leak somewhere.

I was checking all the vehicle data while it was idling and i found a O2 sensor that does the same thing as the fuel rail pressure sensor. It displays data but doesnt shoe voltage. Do you know how both sensors are calibrated before initial start if engine? I read that the FRPS is calibrated every key cycle. So I was wondering what takes care of the calibration. I know its the ECM but what gives it that command, or what wires are the ones that power that action?

I'm inclined to agree with ferris48 about the high pressure fuel pump. The ECM asked for a specific amount of pressure and didn't get it. What's the highest fuel rail pressure you can get out of the pump while commanding it with the scan tool? What brand of fuel pump did you install?

About the fuel rail pressure sensor and temperature voltages - those PIDs may be invalid. From service info regarding the B310 Fuel Pressure Temperature Sensor:

The control module uses the fuel rail pressure sensor to constantly adjust the high pressure fuel pump's feed rate so that the ideal pressure is permanently maintained in the high pressure section (between the high pressure fuel pump and the injectors) by means of a closed loop control. The fuel rail pressure sensor transmits fuel pressure and temperature information via serial data to the control module K20. The sensor's internal microprocessor allows 4 separate sensor outputs from one 3 wire sensor.

In other words, the sensor doesn't generate a normal analog sensor signal, therefore there's no voltage value to display.

It doesn't help that previous versions of the L83 engine actually DID have a fuel rail pressure sensor with two analog outputs. Your Snap-On scanner may be incorrectly displaying those PIDs because it uses the same PID list for both versions.

I attached some pictures, with some information. When i accelerate it for a little while and let it idle i can adjust the pressure to whatever i set it to, but if i just turn it on and idle it it will just remain at 350 more or less. After a while of idling after accelerating pressure drops down back to 300. After i accelerate it for a little while, i can adjust the pressure for about a minute. If i keep accelerating it and adjust it, i can reach almost 2,000 psi before it drops down to 350ish. We are currently in our 4th pump from Orreylis. I checked the injectors as well and they dont seem to be leaking. I added pressure to the injectors and they held pressure. I dont smell any gas on the oil either

Christian9000 wrote:

We are currently in our 4th pump from Orreylis.
 

Now I'm inclined to check the low pressure side. Check for fuel volume and verify with a gauge. This problem is present at idle, so no need to drive it around with a gauge on the window I think.

I just checked it and it is as the sensor reads, pressure does not drop past 70, and when i accelerate, pressure rises to about 80ish psi. Also since the last testing i did, the pressure does not want to go above 800psi. Pressure will go to 800psi and drop down in less that a second to 300. Even if i accelerate like i was doing before, pressure stays at 300ish. In addition, the last test before this happened, i was commandind the pressure to be at 2400 psi( only ever reached about 2000psi never any higher) i started hearing a wine, kind of like a supercharger wine, and then a pop. Pressure hasnt gone up since. My guess it that i blew the pump, furthermore, now there is a slight ticking sound on the top end. I hear it under the intake. Im going to remove it once again and check. Either the pump when out and something happened to the spring, or the roller for the pump when out. Im hoping thats the issue.

Christian9000 wrote:

We are currently in our 4th pump from Orreylis.

...

 i was commandind the pressure to be at 2400 psi( only ever reached about 2000psi never any higher) i started hearing a wine, kind of like a supercharger wine, and then a pop. Pressure hasnt gone up since. My guess it that i blew the pump, furthermore, now there is a slight ticking sound on the top end. I hear it under the intake. Im going to remove it once again and check.
 

Time for an OE pump. GM's are never quite happy with aftermarket for one reason or another, in my experience. If the intake is coming back off again, you might as well make certain that the fifth pump is solid.

I was able to get the pressure to keep at what is desired, but it still doesnt read the fuel rail temperature or the voltage. It keeps saying that the fuel rail pressure sensor learn is inactive. Any ideas on what it could be?

Christian9000 wrote:

it still doesnt read the fuel rail temperature or the voltage. It keeps saying that the fuel rail pressure sensor learn is inactive. Any ideas on what it could be?
 

If the computer's not throwing a code about the temp don't worry about it. Fuel rail sensor R&R makes no mention of a learn procedure, so I'd ignore that learn pid showing inactive too.

Did you install a new pump?

We actually swap out the engine, we tore it down a little because the engine started clicking under the intake. Upon further inspection thay camshaft was damaged and the high pressure fuel pump roller had ceased. It was a little stranger since we had already taken it out and inspected the part. A new longblock had been replaced about 6 months ago so it had warranty. Its running great now, that was our only concern