Fuel gauge just quit working? Says full all the time?

[brads70]

My fuel gauge now says full all the time? Any idea's?

[Chryco Psycho]

pull it out and take a look

[MEK-Dangerfield]

Either the gauge or the wire coming from the sending unit have somehow been shorted to ground.

EDIT:

If you have an Ohm meter, take the wire off the sending unit. Then measure the resistance between that wire peg on the sending unit, and ground(the ground strap). You should measure 15-75 ohms. If so, then the problem is in the wiring or the gauge itself.

[brads70]

Thanks Mike, I'll try that.
Neil I just filled the tank so I'll have to wait a bit. 

[brads70]

Either the gauge or the wire coming from the sending unit have somehow been shorted to ground.

EDIT:

If you have an Ohm meter, take the wire off the sending unit. Then measure the resistance between that wire peg on the sending unit, and ground(the ground strap). You should measure 15-75 ohms. If so, then the problem is in the wiring or the gauge itself.

I just measured it has 0  ohms. So I need a new sending unit?

[MEK-Dangerfield]

I just measured it has 0  ohms. So I need a new sending unit?

Brad,

  I was taking a shot in the dark there, but WOWSA!! You might be OK though...Stick with me here.   

The original sending units had a metal strap that connects to the peg your wire was connected to outside the sending unit. That metal strap might be making contact with the pick up tube, causing it to short out and read full all the time. That happened to me once.     The only other thing I can think of is the float is stuck all the way up, but I can't see how that would happen. I'm curious, have you messed with this sending unit at all?  The downer here is that you have to have less than 1/2 a tank of gas before you can remove the sending unit...otherwise the gas will pour into the ground.   


  Mike

 

[brads70]

Brad,

  I was taking a shot in the dark there, but WOWSA!! You might be OK though...Stick with me here.   

The original sending units had a metal strap that connects to the peg your wire was connected to outside the sending unit. That metal strap might be making contact with the pick up tube, causing it to short out and read full all the time. That happened to me once.     The only other thing I can think of is the float is stuck all the way up, but I can't see how that would happen. I'm curious, have you messed with this sending unit at all?  The downer here is that you have to have less than 1/2 a tank of gas before you can remove the sending unit...otherwise the gas will pour into the ground.   


  Mike

I didn't notice a wire there, just the push on plug to the threaded lug. I did notice a metal strap that is attached to the fuel out nipple to the fuel line ( over top of the rubber connector hose?) I just wiggled that to make sure is was making contact and turned on the key and noticed that the gauge moved from empty to full ( It is full) when I took out the key it slowly goes back to empty. Is this normal? 

[MEK-Dangerfield]

I didn't notice a wire there, just the push on plug to the threaded lug. I did notice a metal strap that is attached to the fuel out nipple to the fuel line ( over top of the rubber connector hose?) I just wiggled that to make sure is was making contact and turned on the key and noticed that the gauge moved from empty to full ( It is full) when I took out the key it slowly goes back to empty. Is this normal? 

The wire I mentioned was indeed what went on the threaded lug.

This sounds normal to me. So are you saying the gauge has always read full?

[brads70]

Mike, is this metal strap your refereing to on the inside ,meaning do I need to pull it out of the tank to see it? More tidbits of info to help diagnose....
I ran the tank out of gas when I was assembling everything, so I put a 5 gallon Jerry can into the tank and started it up ( this was the first time ever I had put gas in it) when I did the fuel gauge said half full? I thought hummm something is up because I'm sure this holds more than 10 gallons! 
When I got it on the road for the first time I drove to a station and put aproximatly another 10 gallons in ( sold in litres here...) and it said full. then after a bit of driving around town it went to half a tank. ( I was pretty heavy on the throttle , first time driving it and all!  ) So I filled it right up! Then I drove around to a few cruize nights and everywhere and anywhere, and the gauge still said full? Thats when I knew something was funky as I put another $ 60 in fuel in it  ( good stuff 94 octane)
I just tested the threaded lug again to ground and I got zero? Is that right?
I have to order a window hardware kit quickly from Dave so I'd like to know if I need a new sending unit too?
Thanks Brad

[tman]

I had the same problem where it read full all the time.  I replaced the sending unit and it worked like  charm. 

[MEK-Dangerfield]

Crap Brad,

  Yeah, this is sounding like a bad sending unit.   

The metal strip I speak of would be inside the tank. This strap was only on the original sending units. The repros got smart and used an insulated wire so things wouldn't short out. The fact that yours once read less than full tells me this is a bad sending unit. Apparently you have to be way low for the gauge to move less than full.

[brads70]

Ok Thanks Mike and tman !    I'll order a new one! Might as well go for a bigger one as mine was a 6 Cylinder car originally. Kill 2 birds with one stone. I 'll order it from Dave at Roseville, the ones he sells seem to have the least problems.
The spending WILL stop eventually right? 

[MEK-Dangerfield]

The spending WILL stop eventually right? 

 Sure....In another 10 years.   


Brad,

   I had NO clue what I was getting into when I bought my car. I knew basic stuff, but this thing died 1/4 mile after driving it the first time. Many fuel related problems and electrical issues, but I am better for it now. I'll just say it taught me. Any info I can pass on makes me feel good. I'll just say this...When you make your first long drive and don't have to call a tow truck, you will know you scored!!   


  Mike

[422STROKER]

Brad, You're pretty handy drive a bit and pull it out.  See if you can't adjust it?  I bought THE cheapest sending unit on ebay I could find, works fine.  I gave it a thorough workout on the bench making sure resistance values were near factory specs.  Seems good so far!

Tom

[brads70]

Brad, You're pretty handy drive a bit and pull it out.  See if you can't adjust it?  I bought THE cheapest sending unit on ebay I could find, works fine.  I gave it a thorough workout on the bench making sure resistance values were near factory specs.  Seems good so far!

Tom

Hi Tom!  
My drivers window sort of fell out. The plastic clips are worn that hold the window to the sliders. So I'm going to order a hardware kit anyhow so I might as well get a fuel sender kit too? I just know if I take this out without having another to put it something will go wrong it will leak and I'll be stuck!    mine has a 5\16 line also, and with my future plans that ain't gonna work.