Fuel tank problems

[AllGreen70RT]

During the Woodward Cruise I was reminded of a problem or two I need to fix, I ran out of gas. The gas gauge which is working properly (grounded sending unit wire to confirm) was reading 3/8 of tank when I ran out of gas. Sounds like a sending unit problem. Any suggestions how to test it? When the tank is full the gauge reads about 3/4 of a tank which leads to the second issue. When I got to a gas station to fill it up, I could only put in 10 gallons. Its a stock tank which I believe holds 18 gallons. The only thing I can think of that would cause this is a plugged vent line. Does that sound correct? What else would only allow me to put in 10 galloons?

Thnaks in advance

[4Cruizn]

I think you need to bend the float down alittle bit to get it to the E position when empty.  As for only allowing 10 gallons in . . .   

[Chryco Psycho]

the gauge may be reading correctly , if the pick up tube is bent up off the bottom of the tank it can easily run out before the tanks is empty , the tank holds 16 gallons on an E body , 18 gal on most B bodys

[AllGreen70RT]

A bent pick-up tube could explain the gauge reading 3/8 of a tank and why I can only put 10 gallons. Though the tank sounded empty when I tapped on it. It doesn't explain why the gauge read about 3/4 when the tank is full. Could that be a problem with the float?

[falcon50flier]

sounds like either the wrong sender is in the tank or there is a combination of float arm + grounding, or another compound problem. If you can get it up in the air with the fuel level low enough to pull the sender, you can troubleshoot directly.

[AllGreen70RT]

I'm beginning to wonder if it has the correct sending unit. Seems strange that I could have two different problems with the sending unit. Looks like my next step is to pull it out.

[4Cruizn]

Easy to do . . if you need anythign, let me know!   

[Chryco Psycho]

I guess ineeded to make it more clear , yes you need to pul the sender & take a look at it

[MEK-Dangerfield]

Here's my guess...   

  If the problem isn't the incorrect sending unit, then the one that is in there now might have twisted some during installation. What I mean is, it might have rotated counter-clockwise some, so the pick-up tube isn't sitting at the bottom of the tank.


  Mike

[AllGreen70RT]

Here's my guess...   

  If the problem isn't the incorrect sending unit, then the one that is in there now might have twisted some during installation. What I mean is, it might have rotated counter-clockwise some, so the pick-up tube isn't sitting at the bottom of the tank.


  Mike

I should be able to determine that by crawling under the car and looking at it. If the fuel line exiting the sending unit is not horizontal to the ground that should indicate its rotated. Does that sound like a fair assumption?

[4Cruizn]

There is a tab on the sending unit usually so you can't install them wrong . . . I think you should pull the tank and then the sending unit for a good inspection.  I may have an old one 5/16 laying around since I upgraded to 3/8.   

[MEK-Dangerfield]

Yes,

  Here is a pic of mine. It kind of goes along with what you said.


  Mike

[AllGreen70RT]

Just took a look at the sending unit, the orientation is the same as yours MEK. The fuel line is at a slight upward angle. 4C is probably correct about the tab.

Hey 4C if you could find that sending unit I could compare it mine and see I have the wrong one.

[4Cruizn]

Just took a look at the sending unit, the orientation is the same as yours MEK. The fuel line is at a slight upward angle. 4C is probably correct about the tab.

Hey 4C if you could find that sending unit I could compare it mine and see I have the wrong one.

I'lll look tomorrow!   

[ShelbyDogg]

Pull the retaining ring off and rotate the whole unit back and forth, you'll hear the sock hitting the bottom of the tank. There is that alignment tab on it so it sounds like it's bent like everyone says. Just slide it out and take a look at it. While it is out, you can work the float to see if the guage deflects from full to empty.  BE CAREFUL around the gas tank.

Rob