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Ask Gm Tech (Cam) Your Own Question
Gm Tech (Cam)
Gm Tech (Cam), GMC Mechanic
Category: GMC
Satisfied Customers: 29534
Experience:  GM Grand Master Technician 2007. 14 year experience.
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GMC C5500: I have a 2006 c5500 flatbed 6.6 duramax allison

Resolved Question:

I have a 2006 c5500 flatbed 6.6 duramax allison auto that has an innaccurate fuel gauge.It operates till it gets to half tank than stays there.On more than one occassion i have run out of fuel.This is a dual tank system (25 gallon midship and 15 gallon rear tank from the factory) and when the front tank runs out there is still 9-10 gallons of fuel in the rear tank. i have already put a rail pump on the truck but did not correct the problem.

Country: United States
Make: GMC
Model: gmc c5500
Year: 2006
Engine: 6.6 duramax

Already Tried:
replaced rail fuel pump
Submitted: 5 years ago.
Category: GMC
Expert:  Gm Tech (Cam) replied 5 years ago.
Hello, I'm Cam. Please include all the details about your issue so I can accurately advise you. I cannot see your vehicle so please be detailed.
Did you check the rear level sensor for behing stuck?
Did you check the resistance?
IS the transfer pump working?
Customer: replied 5 years ago.
Hey Cam i'm Ray. I replaced the rail transfer pump about 4-5 months ago when this problem started but to no avail. As I posted the midship tank (25 gallon) runs dry and the rear tank (15 gallon) has about 9 gallons left in it when this happens(I know this because i've run out of fuel on a couple of occasions lol) I've done some research but it seems that what im hearing is it could be in the ecm. i have not physically checked the rear float being stuck because i figured if its working from full down to half the gauge wouldnt be stuck. (But ive been wrong plenty of times before just ask my x lol)
Expert:  Gm Tech (Cam) replied 5 years ago.
Right, and if it does not see the level in the rear tank it will not transfer.
These are common for float issues and I Suspect that is the case here.
Customer: replied 5 years ago.
Geat thanks,I'll check it.
Expert:  Gm Tech (Cam) replied 5 years ago.
Let me know how it goes.
Gm Tech (Cam) and other GMC Specialists are ready to help you
Customer: replied 5 years ago.
I will thanks