Fuel tank problems

[ShelbyDogg]

MEK,
What's that other wire for in your pic?  It's just kind of hanging there.

Rob

[MEK-Dangerfield]

Rob,

  At the time that pic was taken, I had an electric fuel pump mounted back by the tank. If you are referring to the wire going up thru the trunk... I don't know.  I believe it should go to a trunk light that has been removed. 


  Mike

[ShelbyDogg]

Yeah, that's the wire I see, right through the trunk floor.  The Trunk lights got their power off of the dome light plug. 

Where is the fuel return line?   
Rob

Sorry, I'm a converted EFI guy.   

[MEK-Dangerfield]

Rob,

  I made mine simple. No return fuel line. I have since gone back to a hi-volume mechanical fuel pump. Still no trunk light. 


   Mike

[AllGreen70RT]

Finally got around to pulling the sending unit out. The part number on the unit is 2983072. Can anyone tell me if this the correct sending unit? I rotated the unit and it sounds like the sock is contacting the bottom of the tank. In the empty position the bottom of the float is in-line with the bottom of the sock. So I don't think the float is bent. By moving the float I could not get gauge to go much above 1/2 a tank. Right now I'm thinking that I probably have the correct sending unit it may not be functioning properly. But way does the car seem to run out of gas when there is still 6-8 gallons in the tank?

[4Cruizn]

I do have a sending unit if you want to try a different one.  I don't have an answer for your last question . . . 

[AllGreen70RT]

I do have a sending unit if you want to try a different one.  I don't have an answer for your last question . . . 

Sure
I can compare the two units to see if their the same and see how the gauge works with your sending unit.
Thanks 4C

[4Cruizn]

Is your 3/8 or 5/16??  Mine is the later . . 

[AllGreen70RT]

Is your 3/8 or 5/16??  Mine is the later . . 

5/16"

[Chryco Psycho]

if it runs out with 1/2 tank of fuel it could be the pick up tube is not reaching the bottom but you think it is so the other possibility is if there is a pin hole in the pick up tube it may suck fuel until the pin hole is uncovered at which point it becomes much easier to suck up air than fuel

[4Cruizn]

We'll try a different pickup and see what happens!   

[AllGreen70RT]

Hey 4C thanks for dropping off the sending unit.
Well both units have the same part number and are nearly identical. So I don't have the wrong sending unit and it is not bent. I tested the sending unit from 4C (outside of the tank) and get the same result. It will not go above 5/8 of a tank when the float is in the full up position. If I ground the wire from the gauge, the gauge goes all the way to FULL. What am I missing?  :clueless:Any suggestions for my next step?

[ShelbyDogg]

Try the voltage limiter, on the back of the cluster that your 3 guages plug into.

[AllGreen70RT]

Try the voltage limiter, on the back of the cluster that your 3 guages plug into.

The instrument cluster including the voltage limiter were refurbished a couple months ago by Auto Instruments. Are you thinking the voltage limiter is reducing the voltage too much? If thats the case I will be p*ssed.

[ShelbyDogg]

When you grounded the sending unit return wire, did the guage just go to "F", or did it travel to it's right side limit?  The guages should be pegged to their limit. Same with the oil pressure and water temp. If those 2 others move all the way and the fuel guage doesn't, then it is the fuel guage. If all three have the same problem, then it is the voltage limiter.