damn gauge

[the fall guy]

Hey guys....I was just wondering if you had the same problem with your gas gauge and how to fix it.(85 k5 ) When I fill my tank the gauge reads 3/4 tank...then 1/2 then3/4 again. It's all over the place. then when I first start it up it reads empty then after a while goes back up. I'm thinking it could be my gauge but could it be my sending unit (floats are out of whack) I know that if it reads full out than the sending unit is done but this one has got me confused thanks

 

[R72K5]

flaot could have a hole in it, or its the sender unit regulator wire winding bad

hell might even be a corroded connection at sender


good luck

 

[spearchucker]

float could have a hole in it ...

Isn't the float just a buoyant piece of styrofoam?
The sending unit isn't that compicated of a device, it's just a rheostat. Just make sure the little brass tab is making firm contact throughout it's travel. You can also check it with an ohmmeter. Should read 0 ohms at one extreme and 90 at the other.
First I'd also check to see if there's a short on the sending unit wire somewhere along the frame rail.

 

[dyeager535]

Does the gauge "bounce" when you drive over bumps and what not?

Went through that on mine recently: bouncing gauge is a gauge problem, incorrect readings are going to be sender. (as in never reading full)

Grounding the sending unit wire to the frame SHOULD peg the gauge out, which will test the gauge. Really need to pull the tank/sender to test the sending unit through the full sweep of the float arm.

There is a post about "fixing" the sending unit on the board, should be able to search and find it. It improved the accuracy of my fuel reading, but didn't completely solve it.

The sending unit float is a *styrofoam-like* material. If it wasn't bouyant, it would be consistently erroneous.

 

[goldwing2000]

Isn't the float just a buoyant piece of styrofoam?

The sending unit float is styrofoam. If it wasn't bouyant, it would be consistently erroneous.

Styrofoam melts in gasoline...

 

[dyeager535]

Well whatever it is, (I know styrofoam is buoyant, not sure what to call the material) it's bouyant, and looks/feels like styrofoam. Getting a hole punched in it probably wouldn't affect its operation. Post fixed.

I believe the implication was that the float was a brass float or something like that, when it is in actuality a bouyant material.

 

[goldwing2000]

Just giving you sh!t.

It's probably a urethane of some sort.

 

[4X4HIGH]

Actually, the float in my 89 blazer is a brass float and so was the one in my 76 blazer.

I'm not saying there aren't floats made of something else but mine were both brass.

 

[dyeager535]

I just looked at two Saturday out of a '91 V3500, both plastic.

Three TBI ones I have (87-91) all plastic.

One that came out of my '81 tank, plastic.

All GM A/G-body ('78-88) car ones I've ever seen (10+) plastic.

All later ones I see here are also plastic. (not that you can ever trust aftermarket)

Not trying to start anything either, it's just that I've had more sending units out of "newer" (meaning 70's-80's) GM vehicles than I can count and I've yet to see a brass one.

I'm surprised no one else has chimed in. Maybe we need a poll. lol.

If you've seen what you've seen, thats proof, right? Heck, I've never seen TBI fuel lines that didn't use threaded connections, but others have. Can't say they are liars.