LB7 Mileage

[EdHale]

I have a friend with a 2001 LB7 with just a little over 100,000 miles. It has all new, under warranty, injectors that have been installed for 4-5,000 miles. Recently his fuel sending unit failed. It would show fuel level from full to empty to full changing frequently when the tank was known full. It was determined the fuel sending unit was bad and it was replaced. Absolutely nothing else was done. The strange thing is his fuel mileage has increased noticeably since. What possibly could a new fuel sending unit have to do with increased economy? His mileage is all hand calculated. Here are the details:

2001 GMC Sierra SLT
VIN: 1GTHK23191F183751

Was averaging 14.5 to 15 MPG.
Had fuel guage sending unit (in tank) replaced due to guage always showing empty. No other work done at that time.

1st tank after: 15.8 MPG.
2nd tank after: 16.9 MPG.

2nd tank had approx 175 mile highway trip on it and also approx 20 mile trip pulling trailer with medium size John Deere tractor (with front end loader) on it.

Any ideas?

Thanks.

Ed

[Mark Rinker]

He is seeing normal error on calculating with too small sample sizes.

We keep spreadsheets on every truck over months and months of use, recording gallons of fuel consumed and miles driven.

IMO, the only accurate mileage average is one take with at least 5000 miles of experience...then you have a number that means something.

The error of 1mpg between tankfuls can be caused by the slope away from, or to, the pump where the fuel was pumped.

Sample size.

[EdHale]

I was wondering about that myself Mark, but I appreciate your input. I couldn't image any connection between the fuel sender and an increase in mileage, but what do I know?

I do know that by slowing down my 2006 LBZ is getting 21 mpg on the highway driving at a steady 65. Ed

[Mark Rinker]

An extra-large boat towed 350 miles over two lane Wisonsin highways 57, 54, and 10 today caused me to slow down to about 55mph - or 1900 rpms.

I was rewarded with nearly 10mpg for the loaded segment - usually I get 8 or 9, tops.

Speed not only kills - it drains your bank account, first!!! :D

[precision37]

Maybe the switch back to summer fuel at the pumps.