Strange Fuel Readings

[LouV]

I have a strange problem with my 2008 1500. I recently replaced the fuel pump due to a leaking rusty fuel line.

 

Before the change my usual average mpg on the gage was around 19.5 and the fuel required to fill the tank was pretty close to what the fuel usage was showing. After the change the average MPG is around 21 and the fuel needed to fill the tank is about 3 gallons more than that shown on the fuel used reading.

 

How is the average MPG and fuel used amount determined and how would changing a fuel pump affect that?

 

Thanks,

 

Lou

[Bob D]

Don't know why you changed fuel pump due to leaky fuel line, but...

Fuel leak = decreased mpg s?

No fuel leak = increased mpg s?

"Different" fuel gauge readings is normal when replacing fuel float (pump).

My gauge reads differently (full - empty) after pump change.

[LouV]

The fuel line is one piece with the fuel pump at the tank, Line was all rusted out, no way to run another line. It's a GM gotcha.

 

The fuel usage reading is computer generated from the flow to the engine. For some reason it has started reading incorrectly.

 

Lou