I have 2000 chevy blazer with fuel gauge problems. I am already going to replace the fuel pump next month as soon as I get some cash. My fuel gauge has a habit of always reading full and occasionally empty at stops or even on some steady drives. My fuel pump has 153,000 miles on it and I'm replacing it as preventive maintenance. I know the most common cause for this problem is the sending unit, but could it be the wiring between the sending unit and the instrument cluster? Anyone with late model 2nd gen sending unit wiring problems?

BTW, I will be testing for wiring issues anyway while I'm doing the work around the fuel tank; I just want to know if anyone has had wiring issues.

 

Possibly the ground pack https://blazerforum.com/forum/2nd-ge...problem-42968/ (<--- read that) at the rear but a lot of us have an issue with the gauge reading all over the place.
It's fed by the sending unit as you said, in the tank & the pump cools by being immersed in gas. Let it run low (we all do duh) & it looses some cooling. Who'da thunk it, really.
They also read an average fuel level when in gear but read an actual level when in neutral or park. That being said, try putting it in neutral at a stop light or when nobody is behind you & see if the level jumps around. I know mine does when at a light just after a stop as it's reading the gas floating around in the tank.

 

Here is what it is doing:

 

Like I said in park or neutral it reads actual levels. That's why it bounces around. If you turn it to run & put it in gear does it still bounce around? In gear it reads an average so the gauge doesn't bounce around.

 

No, it holds steady at full only; every now and then it jumps to empty, only to jump back to full. The fuel gauge has been like this for over 5 years (back when it was still my mom's truck).

 

When you change the fuel pump check the wiring harness to the sending unit. Just trace the wire's down and check just to be sure, the new pump will come with a new harness for the pump, but not the sending unit? And like it's been said, they all do it a little.

 

The pump I'm getting is a Delco pump, comes with a new sending unit, my concern was how common are wiring issues? I know how to simulate a sending unit reading through resisters, it's pretty cool we have special variable resister tool at the school that can simulate any resistance you want. I am going built a cheap version for myself just for testing sending unit circuit.

 

Since it has high mileage on it. I'm going to recommend something to you that I just did on my 96 blazer. Put 10 gal of gas in and dump in a 20oz bottle of royal purple MAX CLEAN. i had the same problem and tried that. Half way thru that 10 gal. My gauge started working great. The sensor gets a buildup on it and causes erratic readings.
The max clean cleans everything in ur system. It's awesome. 16 bucks walmart. Worth a try.

 

You put what in your fuel tank?

 

Royal Purple Max Clean is a fuel system cleaner. Runs about $10