07 Silverado aftermarket fuel system

[30thta436]

I am trying to get a 2007.5 Silverado running. This car has twin in tank pumps with -8 line. I deleted the factory fuel pressure sensor and am using an aftermarket fuel pressure regulator and return. The truck will start and run for a few seconds and then die. Truck is also setting DTCs:

0x7EB: P0192 - Fuel Rail Pressure Sensor A Circuit Low (Pending, Current)
0x7EB: P0231 - Fuel Pump Secondary Circuit Low (Pending, Current)

I think it's not seeing fuel pressure and cutting fuel. I can't turn off the DTCs, but is there a setting in HP Tuners where I can eliminate this? Possibly another way around this issue?

[mcfarlnd]

I am trying to get a 2007.5 Silverado running. This car has twin in tank pumps with -8 line. I deleted the factory fuel pressure sensor and am using an aftermarket fuel pressure regulator and return. The truck will start and run for a few seconds and then die. Truck is also setting DTCs:

0x7EB: P0192 - Fuel Rail Pressure Sensor A Circuit Low (Pending, Current)
0x7EB: P0231 - Fuel Pump Secondary Circuit Low (Pending, Current)

I think it's not seeing fuel pressure and cutting fuel. I can't turn off the DTCs, but is there a setting in HP Tuners where I can eliminate this? Possibly another way around this issue?

Did you do anything with the FSCM? Wiring to bypass it? I personally would keep the pressure sensor. Is there any reason why you removed it?

[30thta436]

I am getting my power for the pumps from the FSCM and grounds are just a chassis ground, the sensor was not removed for any reason in particular, other than I didn't calculate fittings for it when I was buying for the fuel system and I didn't think I would need it, but now I'm thinking the ECM needs to see fuel pressure to continue to deliver fuel, is this thought correct?

[mcfarlnd]

Well, depending how you have the pump wired, that could be an issue as well. If the FSCM is being used for power, it most likely will need the pressure sensor which is where the pressure sensor calibration is stored and I believe the DTC for it is too. If you get your power PRIOR to the FSCM, utilizing a relay. Then, remove the fuse for the FSCM and remove the FSCM codes in the ECM ("No error reported"). Essentially, in the end, you want to completely bypass the FSCM and not have any input from it. To remove codes in the FSCM, you will need the Beta version but, I haven't done exactly what you are stating and can't guarantee another issue will not arise. Most just completely remove the FSCM from the picture as stated above. My system still uses an FSCM to modulate the pressure with a single walboro 450.

[tomrog123]

Going to bump this. Don?t know which route to go either bypass the FSCM or use it. The simple way in my mind is to bypass, however with that arises another question? does the FSCM control the fuel gauge on the cluster? I?d like to keep factory gauges working. Could someone smarter than me dumb it down?? TIA

2010 Sierra Denali -8 feed, using factory feed as the return. Twin walbro 450?s for now, going to have one pump on a Hobbs switch. Basically what I?m asking is does the ecu still trigger the factory pump (via the fscm)?? I assume there will be a slew of codes to turn off just need a little guidance

[cmitchell17]

Going to bump this. Don?t know which route to go either bypass the FSCM or use it. The simple way in my mind is to bypass, however with that arises another question? does the FSCM control the fuel gauge on the cluster? I?d like to keep factory gauges working. Could someone smarter than me dumb it down?? TIA

2010 Sierra Denali -8 feed, using factory feed as the return. Twin walbro 450?s for now, going to have one pump on a Hobbs switch. Basically what I?m asking is does the ecu still trigger the factory pump (via the fscm)?? I assume there will be a slew of codes to turn off just need a little guidance

I think the only thing the ECU does is command a desired fuel rail pressure to the FPCM, then the FPCM does all the logic and feedback itself to get to that fuel pressure based on the demand and how much the injectors are being opened. But you will still have to have something to run the walbro pumps, but then I don't think you can use the FPCM because I don't think you can PWM the walbro pumps, but maybe you can not sure. You may be able to get the FPCM into a default fail safe mode to drive it though. There is also a option to tell, interestingly enough the FPCM itself, weather there is a FPCM or not, and also if there is a "fixed" or "variable" pump which I assume means a regular or PWM driven pump. But I would bet these probably have zero effect like 95% of the switches and tables and functions available to us.

It may be as simple as enabling one DTC in the FPCM to trigger which would maybe drive a fixed voltage signal so you can drive your pump.

It appears the ECM still controls fuel gauge stuff, since the tables for the fuel gauge are "ECM" tables.

I have a 2011 Denali L9H that I am trying to push the system to get more fuel from the stock pump. I currently have too many other issues as well haha, but there is just so little information out there its really surprising. It's like 99% of the stuff is for GMT-800s and people love to disable and delete things as well, so you don't have anyone trying to integrate things correctly, but its understandable with how finicky and frustrating these things can be.

[cmitchell17]

Wait, nevermind it looks like the FPCM fitted yes or no switch and the fuel pump fixed or variable switch are actually ECM tables. So maybe its just as easy as disabling that switch? It looks like there is still a ECM table with a min and max duty cycle and a base. I think the fuel pressure signal is wired to the ECM as well so it maybe might just be that easy, just switch the FPCM fitted switch to no, then turn the fuel pump to fixed, and probably 100% all the ECM duty cycle tables to be sure.

You wouldn't even have to buy extra credits to tune your FPCM. I can already pretty much tell you I have access to my FPCM and all the stuff in there hasn't done a thing to help me get more fuel unfortunately.

[tomrog123]

Thanks for the feedback! I?ll have to do some digging into my tune and find out. Everything your saying makes sense. Ive talked to some guys on other platforms that still use the fscm to control pressure off of one pump, my thing is I like to keep it simple (so I can fix it later &#128514

[BigTuner]

I tuned a car for someone where they deleted the FPCM and ran an return fuel system, it was a gen V but maybe you can find some of it helpful.

[cmitchell17]

Thanks for the feedback! I?ll have to do some digging into my tune and find out. Everything your saying makes sense. Ive talked to some guys on other platforms that still use the fscm to control pressure off of one pump, my thing is I like to keep it simple (so I can fix it later ��)

I feel like with what we have, there is room to push the stock stuff I just think everyone likes to just delete it all. I don't like to do it that way because it takes away the sleeperness of it and introduces all kinds of unwanted and POS car sounds and quirks that just make it look like a POS haha. I mean I understand why you deleted it probably out of frustration.

Unfortunately it may take flashing every combination of one and zero in the FPCM and ECM to figure it out.

These things (GEN IV and GEN IV control and fuel systems and E38s and FPCMs) have been out for getting close to almost 20 years now.