Hey guys, here's another thread that concerns weird things that a GMT900 series pickup does. After the addition of my new fuel system I have been battling my FPCM, and the boost referenced regulator.
I'm running a twin Walbro 255 in tank fuel pump setup, one fuel pump being powered off the trucks fuel pump circuit, the other connected to a Kenne Bell BAP, which is triggered off of a Hobbs switch set to 3 psi boost.
Problem is, the regulator is set to 58psi then boost referenced off the manifold.
The FPCM however only knows low flow, normal, and high flow conditions. So I set normal and low flow to 53psi as that's where it idles at with vacuum on the manifold, and 72psi for high flow as that's 14psi boost.
Problem is, at mid boost levels the FPCM is commanding 72psi fuel pressure but delivered fuel pressure due to the regulator is only 66psi or so as it will only be boosting 8 psi which trips a CEL of the fuel rail pressure sensor going haywire.
How in the hell do you get around this problem? Is there a way to just disable the FPCM and let the primary pump run at 12 volts all the time without the CEL being tripped? I can't disable it in the tune![]()