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THEFERMANATOR
June 10th, 2009, 02:44 PM
How does the fuel pump control circuit work inside of an 01 LB7 ECM? I am hooking up a lift pump and was wanting to know if this circuit could be used to control it or if there is a table in EFILIVE I can use to set it up? I am currently building my project and doing the wiring and was deciding wether to keep my oil pressure switch to turn on my lift pump or to use the ECM.
chevydieselsmoker
June 11th, 2009, 07:18 AM
there isnt a fuel pump function available to us in the ecm. you could use the dsp output though if you plan to run a dsp tune
THEFERMANATOR
June 12th, 2009, 04:13 PM
I know my ECM has one in it that was used for the transfer pump if it had dual tanks, didn't know if this circuit could be converted or not to power a lift pump for the engine instead of the transfer pump that pumped fuel from the rear tank to the front tank.
Zorganov
August 8th, 2013, 01:55 PM
Wondering how you made out with this?

GM data says the transfer pump turns on when the rear tank level is higher than the front by a certain amount, and once the front is higher by a certain amount, the pump is disabled again. In effect averaging the fuel level between the two. The fuel gauge does operate on a combined signal of the two tanks.

I'm trying to use this same circuit to use the pump as designed but so far no luck with rescaling the secondary sensor with EFI Live. My next step is physically wiring in a potentiometer into the circuit and watching the data. I have successfully engaged the pump with EFI Live scan tool, but so far no other progress.
THEFERMANATOR
August 8th, 2013, 02:59 PM
I ended up using a 6.5 oil pressure sensor as it is a 3 wire. 1 wire for the gauge, and the other 2 were for the fuel pump. So mine runs when the engine is running. The 01-02 trucks can use the 6.5 diesel sending unit and use it to power the fuel pump relay. I know most just wire it to run when the key is on.
Zorganov
August 9th, 2013, 12:00 AM
Don't mean to hijack your thread here, but do you know any more about the transfer pump circuit, do I need a different OS to make it work? or is the logic all in place, it just needs to see the secondary sending unit value?
THEFERMANATOR
August 9th, 2013, 05:13 AM
Don't mean to hijack your thread here, but do you know any more about the transfer pump circuit, do I need a different OS to make it work? or is the logic all in place, it just needs to see the secondary sending unit value?
You have to run a cab and chassis fuel system in the ECM to make it work. Also it must see 2 working level units or else it will default the gauge to empty and not trigger the transfer pump.