this is my first post. yesterday I just bought a used 1996 s-10 blazer 4 dr automatic. when i bought it there was about 1/3 tank of fuel so i put about 40 liters in it the gauge then was showing 3/4. i had a 250 km drive home on the way the fuel gauge was working correct ( i think) but after awhile it started jumping a long way up pass the full mark. when i started it today it was showing about 1/3 tank of fuel and on the way to the garage to get it inspected for title transfer it ran out of gas but was still showing 1/3 tank. could this be the sending unit or the ground wire, the last owner said that there was a new fuel pump installed. thanks in advance for any help.

 

How long ago was the new pump installed? Sounds like classic sending unit failures.

*Moving to 2nd Gen Tech*

We are cleaning out the Gen Tech section to close it out in favor of keeping everything in the respective generational sections.

 

Definitely the sending unit is bad. These trucks are horrendous for this. Best thing to do is fill up every 200 miles to begin with (or 320km) and find out how much you've got left in the tank. Youdon't want to go below a quarter of a tank as the fuel is also the lube and coolant for the pump. I'm going to guess that you have a 19ish gallon tank as I have no idea if there is a difference between a 2dr and 4dr tank. When you get somewhat dialed in to where it take you about 15 gal or 60 litres to fill up you'll be right on target.

Yes, I spelt litres right!

Of course, you could always drop the tank and buy a new pump and sending unit and install them. My recommendation is to leave it be until you need a new fuel pump again. Could be a short time if the previous owner didn't use a GM pump.

 

i hope it's a gm noe. i don't know how long ago it was put in.