Fuel Gauge Issues

[MickeyD]

Hello all,

An issue cropped up on my dad's 2003 Suburban yesterday that I'd like some help with diagnosing. He filled it at a gas station, then after that, the fuel gauge has decided to point every which way. The gauge was pointing around the 5 o'clock position (way past full), then back some, then even further to the 7 o'clock position. Basically, it's not stuck one way, but rather, it decides to point in seemingly random directions.

From the bit of reading I've done, I suspect the culprit is the stepper motor for the gauge in the cluster. I know the sending unit can also cause the gauge to read incorrect or to get stuck, but because of the erratic behavior of the gauge, and the fact that I believe the sending unit was replaced as part of some maintenance a few years back, I don't think this is it.

Oddly enough, it seems that the gauge for the oil pressure is also acting up. It seems to peg at maximum pressure. I know this may be a separate issue (we haven't had to replace the sender or the screen under it yet), but I thought I'd add it. I suppose a grounding issue on the cluster or the fuel level sender could also be the culprit.

What I'm asking is 1) is this a common issue and 2) what is the common mode of failure? It's not a problem for me to replace the stepper motor if that's the issue (I'm an electrical engineer, easy repair). But if it's common for the sender to fail causing this, that's a little less fun to fix.

Thanks for the input!

 

[TollKeeper]

Stepper motors are extremely common. You can check local listings for a local rebuilder, or try eBay.

I got a local rebuilder last year. He charged 120 to put all new stepper motors, and replace any burnt bulbs. For an additional 30, I could have done a custom color LED bulb replacement.

 

[Fless]

There should not be a filter screen underneath the oil pressure sender in an NBS. EDIT: what does the oil pressure gauge do when you turn the key to run, without starting the engine?

If you do the stepper motor, do Dad a favor and do them all. For a quality kit that has the best stepper motors and replacement dash lights (you know, check and fix those while you're in there...) you'll spend about $25-$30. Once you have opened up the cluster, they're all the same work.

 

[MickeyD]

Hey, thanks for the input!

It's good to know this is a common issue. Think I'll just replace them and be done with it.

And about the filter screen for the sender, that's good to know. I'm used to my NNBS, so I didn't know about the NBS not having one. The oil pressure gauge hangs our around 80 PSI with the car off and with the key to the run position, then it wiggles past 80 PSI when running. There's no DTC codes relating to these issues.

Think I'll search around, then order a set of servos and do them all.

 

[Fless]

I've had good results with Dr. Speedometer kits, they have a few different ones. I don't use the solder they provide.

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[bigdog9191999]

i have had a couple of these trucks now in the 02/03 range act up on a full tank, after it comes down off full it reads accurate. my guess is the sending unit is off the charts when full and when it comes down it acts normal.. mine has done this for years reliably.


we also separately have the oil pressure pegged all the time ( the needle does a normal sweep at key on then pegs out, indicating a bad pressure switch. )



so although it would not hurt to have the cluster done, it may not be the issue either. i would watch the miles and run some fuel out first and see what the gauge does. you should know within a couple hundred miles (mine is usually in about the first 60-80 after a fill)

 

[treehan77]

You can also hook up a cheap scan tool and see what it says the fuel % remaining is. If you know it’s full or empty or half or whatever, and THAT reads differently, it’s not the gauge.

 

[rockola1971]

Check your miles left on tank in the driver information center of your cluster. If it is correctly reading then your sending unit is ok and its your stepper motor.

These instrument clusters are notorious for throwing up on themselves. Whether it be stepper motor failure and/or silver migration on the rear of the circuit board (Instrument CLuster PCB).

 

[MickeyD]

Hi,

Thanks for the input all.

I wound up just replacing the stepper motors (and a few burnt out light bulbs) and the issue is resolved. No apparent issue with the sender or anything in the tank.