Is it something that can be fixed easily or replace the pump assembly? Is the punp accessable by cutting a hole from the inside?

 

It can be the sender unit in the tank but it can also be a number of other things like the gauge, power, ground, wiring, the class 2 serial data bus etc. You could get clever to narrow it down by say inserting a resistor of a mid tank value in the sender circuit to see if the gauge remains stable depending on your wiring and soldering skills.

I saw a post here years ago where a member cut a removable section out of the rear passenger floor to gain access to the pump unit. Be careful, sparks and gasoline are involved. My Toyota has this and it’s priceless. Blazers unfortunately, not so much.

George

 

Found the thread:

https://blazerforum.com/forum/2nd-ge...replace-92490/

George