Thanks Kyle!! So my problem is the Fuel Level Sensor for sure?? I'll do a search and hopefully find the PN. They did quote me $150.00, give or take a buck or two. This was actually 3 different Chevy dealerships. Unfortunately, that particular part isn't available at Napa, Schucks, Auto Zone or Car Quest. They all sell the entire Pump Assembly/Module. This includes the pump, pressure sending unit and Fuel Level Sensor.

I am going to get a scan done at Auto Zone as soon as my girlfriend, who has the Blazer, gets off work. Auto Zone is telling me that their scan will only tell me codes if the Check Engine Light is on, which it isn't...and that their scan is only for Emissions problems. Hoping it's more indepth than that. I'll find out in a few hours.

 

Actually, it is one of three things. Wiring, sending unit, or gauge. Sending unit being the most popular problem.

 

Just to clarify, when you say sending unit, are you refering to the Pressure Sending Unit or what the dealer calls the Fuel Level Sensor? Gauge seems to work, as it does move...at least that tells me it's not frozen. Guess it doesn't actually mean it's working properly.

 

By sending unit, I mean fuel level sending unit. I guess it could be called a sensor as well, but for as long as I have been working on automobiles, it has been called a sending unit as it is all pretty much mechanical.

Basically, what happens if high sulfur content fuels are used for prolonged periods of time with out using a fuel system treatment (Chevron Techron Fuel System Treatment Plus or equivalent), the sulfur will buildup on the resistor grid and corrode the fine wires. You may still see somewhat correct fuel level readings at certain points during the course of using a tank of fuel, but there will be spots where it will be quite erratic.

One way to check to make sure that it is the sending unit and not a wire problem is to disconnect the return wire from the sending unit to the BCM. You would basically have to disconnect the harness at the tank and remove the proper wire from the connector, then reconnect it. If, after driving it around for a bit, the gauge still fluctuates, then you have a problem with either the gauge or the wire.

 

So in order to do this test, I'd still need to at least lower the tank to gain access to this wiring harness? Took the rig to Auto Zone, and no error codes at all came up. Sorry to keep bugging everyone about this. Just wanting to nail the problem down as soon as possible. I leave for an extended work trip Sunday morning and will be taking the Blazer. Guess I'll be relying on the trip odometer during this trip and attempt to get the problem fixed when I return.