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Discussion Starter · #1 ·
Hey guys,

I can use some help. I have researched and learned so much online the last couple of months but I still can not figure out my issue.

I have a 2003 Suburban that has a LBZ installed in it. Everything is fine with the install with the exception of the dual tank tuning. This is where I can really use some help.

I had DuramaxTuner install a dual tank setup when I purchased EFI Jack DSP5 Tunes from them. Boy did the tunes make a huge difference in performance! Having the dual tank programming added, the dual tank function does not operated. I have went through all the wiring, fuel level sensors and the transfer pump, and everything checks out 100%. I checked the operation of the pump and fuel level sensors at the ECM; both fuel level sensors read at the ECM and I can manually run the transfer pump from the ECM as well. Even with everything appearing to be installed correctly the aux fuel tank gauge does not change the dash fuel reading when I manually change the aux tank float position nor does the dash gauge change when I unplug the rear sending unit. Also, I get no trouble codes for the dual tank setup not functioning. All this is telling me that the dual tank tune does not exist, right?

So I think it can be an issue with how DuramaxTuner installed the dual tank tune or an issue with my ECM. Is there anything else it could be? Bob/Jim at DuramaxTuner believes the dual tank tune is programmed correctly but it just does not add up.

I would appreciate any help on getting this resolved.

Thanks in advance.
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