for some reason I have these two problems with my truck!

When I am on the front tank gas gauge bounces around like a HDD Kid with lots of sugar, I know when I am low on gas on that thank when it goes to F and stays there.

Problem number 2.

My gas keeps going from front to rear at all times making it nearly impossible for me to get an accurate reading on my mpg any help I'd appreciate it!

 

look in the tech article stickyd at top I think it has a post there for the fuel running from one tank to another.

 

Is the needle constantly moving, or just when your on the gas?

The TSB involves installing a one way valve on the return line. Haven't done it to my truck, but doesn't seem to be a major job.

 

mostly when I get on the gas or when I have to come to a quick stop. what is the TSB all about?

 

You have 2 problems. The fuel level thing is a bad float or possibly a gauge if it happens the same on both tanks. Fuel transfer between tanks is due to broken check valves in the fuel sending unit inside the tank.

 

and in order for me to replace the fuel sending unit I will have to buy a new (in tank fuel pump?)

 

check Auto Parts Fast at RockAuto they will give you the answer to that question

 

The sending unit does come apart so if you can source another new/used you can replace just what's necessary.