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Welcome to the 3500HD.com forum created October 2009

Author Topic: Fuel Transfer  (Read 1023 times)

Rey

  • Single Axle Driver
  • *
  • Posts: 9
Fuel Transfer
« on: December 15, 2016, 09:23:29 PM »
Ok.....last Friday, December 9, I filled up both tanks on my truck.  It took 34 Gallons.... 16 gallons in the front tank, 18 in the rear tank. $80 total ..... I have been driving it for a week now and the trip is at 160 miles and the fuel gauge is at 3/4 tank.... My question is.. When exactly does the rear pump start transferring the fuel to the front tank......  First time I fill up the tanks since I got the truck ( a month ago) 

ED-NY

  • Administrator
  • 3500HD Hero
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  • Age: 67
  • Location: Champlain, NY
Re: Fuel Transfer
« Reply #1 on: December 15, 2016, 09:41:56 PM »
I'm sure someone will jump in to answer...but what year is the truck..that might make a difference.

RPF207

  • 3500HD Driver
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  • Age: 29
  • Location: Maine
Re: Fuel Transfer
« Reply #2 on: December 15, 2016, 09:48:17 PM »
From what I've read, the rear tank just pumps into the front tank keeping them at equal levels. Levels as in 1/4, 1/2, full, whatever it may be. Not equal levels as in gallons because the two tank are not both the same size. So if your fuel gauge reads 1/2, they are both at half.
1999 chevy HD 4x4 135.5" 6.5 nv4500 bw4470 Dana 70 HP 10 lug front

Due to recent budget cuts the light at the end of the tunnel has been turned off

Rey

  • Single Axle Driver
  • *
  • Posts: 9
Re: Fuel Transfer
« Reply #3 on: December 16, 2016, 09:47:20 PM »
HMMMM.... Well right now it is about to get to half.... I'd say it's at 9/16.... but the trip now reads 185..... I was hoping to get at least 400 miles from my two full tanks !!! Last time I was at empty, and filled up 10 Gallons in the front tank... was like $23.... any way it got me 130 from the 10 Gallons.... so if that is 13mpg... that would put me at 442 miles with 34 gallons....

any thoughts...

2000 Chevy 3500HD 6.5 Diesel

GM Guy

  • 3500HD Driver
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  • Age: 27
  • Location: NW. KS to S. ID
  • manual transmission 2wd enthusiast
Re: Fuel Transfer
« Reply #4 on: December 22, 2016, 02:20:13 AM »
total system capacity IIRC is 40 gallons, 22 front 18 rear.

The way I understand it, the balance module kicks on the rear tank every time the front sending unit falls below that of the rear, and continues till empty.

as far as mpg, we usually got 10-12 mpg under load with dad's 92 HD 6.5L 5spd. is yours auto or 5spd? auto will hurt mpgs some. We never got to try it out empty for mpgs, allways had a load on it. :)

Rey

  • Single Axle Driver
  • *
  • Posts: 9
Re: Fuel Transfer
« Reply #5 on: December 26, 2016, 03:15:13 PM »
Ok.... So I just came from the gas station close to home and here is what I found....

My fuel gauge was on the red with only 295 miles on the trip.

So I start fueling the front tank and after five gallons... THE NOZZLE STOPS !!!

I press the nozzle again and again it stops !!!

Then I start Refueling the rear tank..... Took 16 Gallons before it tripped again ....

Is it feeding off the rear tank only ????   anyone else's doing this as well ???   

GM Guy

  • 3500HD Driver
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  • Age: 27
  • Location: NW. KS to S. ID
  • manual transmission 2wd enthusiast
Re: Fuel Transfer
« Reply #6 on: January 02, 2017, 02:20:24 AM »
Rey, it is operating somewhat normally, all the business of fuel suction and return is done off the front tank, so it is allways "running on the front tank" there is no switching between tanks. The rear tank is a slave unit that all it does is pump fuel from the back tank into the front tank.

I am curious why the guage is reading wrong though. might pack a jug with you till you can figure it out. :)

As far as the mpgs, the best thing that can be done is maintenance. keep the whole system happy and healthy and she will do as good as she can.

 


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