Fuel guage bounces?

[Matt69olds]

I seem to recall reading about a fix for this.

My wife drove the square for the first time yesterday. After getting out she asked what the deal was with the fuel gauge?

It does bounce, a lot! It’s been like that for as long as I can remember. It’s not unusual for it to bounce from 1/4 to past full just driving around turns. I understand these trucks didn’t have the most rock solid fuel gauges, but there is definitely lots of room for improvement.
BTW, the gauge is accurate. Meaning when you are sitting still, and it reads empty, it’s actually pretty close to empty.

 

[fast 99]

bump

Kind of curious on this one too. 85K20 tach cluster, small fuel gauge lower left. Thought of installing inline condenser, suspect bad gauge.

 

[TotalyHucked]

Well remember, the carb'd trucks never had any kind of baffle in the tank at all so there's ALOT of slosh going on when you get down past a half tank. Every non-baffled, carb'd vehicle I've ever driven has done that so I've never questioned if it could be improved lol

 

[squaredeal91]

Well remember, the carb'd trucks never had any kind of baffle in the tank at all so there's ALOT of slosh going on when you get down past a half tank. Every non-baffled, carb'd vehicle I've ever driven has done that so I've never questioned if it could be improved lol

So could a guy put in the efi baffled tank and run the old sending unit?

 

[squaredeal91]

My 78 fuel gauge does seem to move around more than my 91.
In the later squares I wonder if they used a diode like Ford to help steady it?

 

[SquareRoot]

So could a guy put in the efi baffled tank and run the old sending unit?

Yes but, I doubt it will fix the bouncing gauge. The baffle is nothing more than a tub that is spot welded to the bottom of the tank. It's only about 8 x 8 inches square and maybe 2-3 inches tall. Just enough for the electric pump to sit inside of. I think the arm of the float is actually bent such that it sits outside the baffle.

 

[GTX63]

Most of the squarebodies pre tbi had resistors on the back of the gauge and they can vary over time. In this case we are talking decades. I think the new replacement gauges have been updated and eliminated the resistor. Floats can also be like fishing bobbers. I replaced three (used) fuel gauges in an 85 K10 and they all acted differently. These third world fuel sending units are awful. It also took three units before I had one that functioned. Fortunately, I bench tested each one before installation.

 

[SquareRoot]

Or, you could step into the 21st century and add Dakota Digital Gauges? That will fix the bounce house issue...

 

[TotalyHucked]

Or, you could step into the 21st century and add Dakota Digital Gauges? That will fix the bounce house issue...

Exactly! My gauge is rock solid

 

[squaredeal91]

Or, you could step into the 21st century and add Dakota Digital Gauges? That will fix the bounce house issue...

I'll stay in the past lol

 

[fast 99]

Know the gauges bounce somewhat from open design of the tank. This gauge bounces rapidly from full to empty when driving with 1/2 tank. It is NOT normal. No way GM would have sold a new vehicle like that. Not opposed to replacing the gauge if that will fix it. Just asking if there is another possible fix or if a new gauge is needed.

 

[Grit dog]

Everything I’ve read is it needs a/the resistor or the resistor replaced on the back of the gauge. Used to have a link to buy the proper one. But then decided I don’t care. It reads right when you stop.
Blue truck does this. Bounces back n forth maybe 10-20 degrees whenever truck is in motion.
The 77 does not. It moves appropriately when going up/down hill hard cornering or accel or braking. Moves about 1/8 tank slowly depending which way the fuel is getting pushed in the tank.

 

[Grit dog]

Found the thread on here. Just posted to bring it to the top in the tech discussion forum.

 

[Matt69olds]

I wouldn’t be opposed to replacing the fuel gauge if it fixes the issue.

Since the truck was originally diesel powered, i swapped in a standard fuel gauge to replace the one that said “diesel fuel only”. I didn’t realize GM changed the coloring and font on the lettering until I was ready to bolt it in. I figured eventually I’d replace it with the correct part.

Thirty years later, I’ll “eventually” get to it.

 

[squaredeal91]

I posted in other thread too. Found these. According to spec they will work. But there physically different. Idk I'm not an electronic guy lol.