99 Blazer 4.3 Voltec with the unstable Fuel Gauge.

[ruger17hmr]

Each instrument cluster gauge has its own individual stepper motor, in other words there is one for the speedo, tach, temp gauge, oil pressure, voltmeter, etc. Here is a seller on ebay for them with pictures of the actual stepper motors. GM Stepper Motor Kit | eBay

Thanks for the info. I did not know that.

 

[ruger17hmr]

It's the one connected to the fuel gauge. The stepper motor physically moves the needle. My bet is still on the sending unit, though.

The sending unit was my initial guess. And, I am leaning towards it at this moment.

 

[GTM]

I had a 94 S-10 Blazer. Dropping the tank isn't too bad. It probably took more time to siphon the gas than anything else.

 

[remauto1187]

The sending unit was my initial guess. And, I am leaning towards it at this moment.

"easiest" way to see whether the fuel level potentiometer or the instrument cluster fuel gauge stepper motor is the culprit is to put a voltmeter on the signal wire coming off the fuel pump module. Check for major voltage swings while vehicle is stationary. While you are there clean the snot out of the ground wire connection.

 

[ruger17hmr]

"easiest" way to see whether the fuel level potentiometer or the instrument cluster fuel gauge stepper motor is the culprit is to put a voltmeter on the signal wire coming off the fuel pump module. Check for major voltage swings while vehicle is stationary. While you are there clean the snot out of the ground wire connection.

So, do the major voltage swings indicate a faulty or normal Sending unit?

 

[metaldog]

1999 CHEVROLET BLAZER Fuel Pump

 

[Ronnie P]

Check out www.tristarrradiator.com They will explain why you're sending unit does that. They build new ones out of copper for 89 bucks

 

[ruger17hmr]

Check out www.tristarrradiator.com They will explain why you're sending unit does that. They build new ones out of copper for 89 bucks

It is really driving me crazy. The fuel gauge is now working most of time, but it does drift a little from the correct reading time to time. The needle does go back to the correct reading after the drifting. Only thing I did from the last posting was to fill up the gas tank with $10 worth of Gas.

What gives?

 

[remauto1187]

It is really driving me crazy. The fuel gauge is now working most of time, but it does drift a little from the correct reading time to time. The needle does go back to the correct reading after the drifting. Only thing I did from the last posting was to fill up the gas tank with $10 worth of Gas.

What gives?

Could be the stepper motor that drives the fuel gauge needle, potentiometer down in the tank with the fuel float attached to it, associated wiring (dirty connection), dirty ground connection (usually at the tank), dirty, loose connection behind the instrument cluster where the signal from the fuel level sender(potentiometer) comes in to cluster, or even noise coming off the alternator getting into the instrument cluster power supply. Feel like throwing parts at it? Or break it down and figure out where the noise is NOT. You will need a digital voltmeter.

 

[ruger17hmr]

Could be the stepper motor that drives the fuel gauge needle, potentiometer down in the tank with the fuel float attached to it, associated wiring (dirty connection), dirty ground connection (usually at the tank), dirty, loose connection behind the instrument cluster where the signal from the fuel level sender(potentiometer) comes in to cluster, or even noise coming off the alternator getting into the instrument cluster power supply. Feel like throwing parts at it? Or break it down and figure out where the noise is NOT. You will need a digital voltmeter.

I have never used Volt Meter in my life, but I will give it a go. Just have to locate a correct signal wire leading to the Fuel Module.
I will post the results.

 

[flhultra]

mine 99 blazer - gauge stop working then about 2 months later fuel pump went out.
(change it all out after the pump goes)

 

[ruger17hmr]

mine 99 blazer - gauge stop working then about 2 months later fuel pump went out.
(change it all out after the pump goes)

That is one way to confirm it, I suppose. LOL

 

[printcraft]

I have a 99 Tahoe with a fuel gauge that reads accurately but the needle is vibrating like a humming bird wing.

 

[remauto1187]

I have a 99 Tahoe with a fuel gauge that reads accurately but the needle is vibrating like a humming bird wing.

95% chance its the stepper motor that drives the needle. Its a common problem. My 99 GMC Sierra which has the same instrument cluster as your Tahoe USE TO have the same problem. I replaced the stepper motor for $5 and it took care of it. That Sierra has had 2 AC DELCO fuel pumps installed since the original died at 120K miles. Hey, the Sierra has 265K miles on it.

 

[printcraft]

95% chance its the stepper motor that drives the needle. Its a common problem. My 99 GMC Sierra which has the same instrument cluster as your Tahoe USE TO have the same problem. I replaced the stepper motor for $5 and it took care of it. That Sierra has had 2 AC DELCO fuel pumps installed since the original died at 120K miles. Hey, the Sierra has 265K miles on it.

Where can I get that particular motor, do I have to do a pick-a-part or are they available new?

I've got about 190K on the Tahoe.

 

[remauto1187]

Where can I get that particular motor, do I have to do a pick-a-part or are they available new?

I've got about 190K on the Tahoe.

You can get them off ebay. You will need to know which ones you have (all gauges, speedo, etc. use the same model stepper motor). The number is on the rear side of the stepper motor plastic housing. It will be something along the lines of X25.168. There are replacements that supersede the original part# that dont have the failure rate of the original GM part. Removing the instrument cluster takes 5mins or so. Being careful with the instrument cluster it takes 10mins or so to remove printed circuit board from the plastic instrument cluster housing to be able to read the part#'s of the motors. Here is a video on youtube to give you a general idea on replacing them and setting the new ones up to your old setting so the cluster wont need calibrated. GM Stepper Motor Replacement and Instrument Panel Disassembly - YouTube If you dont have experience in the correct way to solder you can destroy the delicate traces on the circuit board that lead to each stepper motor. There are 4 connections that have to be desoldered for EACH stepper motor that you replace. Dont use a soldering GUN! Use a 30/35w iron or an adjustable temp solder station. All kinds of videos on soldering on youtube as well. YOUR CLUSTER IS NOT SOMETHING YOU WANT TO PRACTICE SOLDERING SKILLS ON!!