Fuel Gage Woes
 

I have searched here and on the Chevelle website, and looked at a number of youtube videos on the subject......and I'm still unclear on the problem I have.

The problem: all of a sudden, the gas gauge on my 69 Chevelle (which had been working only half-assed accurately) went to WAY past full and stayed there. Did some tests based on reading past threads and looking at youtube videos, and best guess was that the sending unit went bad. So, I dropped the gas tank and pulled the sending unit out. Using an ohm meter on the sending unit, I find that at the low point of the float (i.e., empty tank) it reads 10 -15 ohms. Moving the float to the high point (full tank), it reads 120 - 125 ohms. When I take the sending unit and hook it up in the trunk of the car with the tan wire (from the gauge) connected to the sending unit and the ground wire from the sending unit to a good ground in the trunk, moving the float on the sending unit through its full range of motion (with the ignition switch on) has no effect on the pointer on the gauge....it stays WAY past full. When I completely disconnect the sending unit, and just ground the tan wire from the gauge, with the ignition on, the gauge moves perfectly to the 'E' mark. Unground the gauge with the ignition on and it returns to WAY past full.

Any ideas?

Bill is that sender new? Perhaps Rick will chime in....did Rick replace that sender?

Dan

No, sender certainly appears to be original. Someone has had the tank out of the car before, with resulting damage to both ground wire and gauge wire....both poorly repaired. No insulating material between tank and trunk floor either, although you can definitely see evidence on the tank that it was there originally.

Well that rules out a bad new repop sender.....very typical what you are describing. I assume you cleaned the ground and installed a new star washer.

Dan

Sender is definitely not a repop, as it says "AC Made in USA" on top. The end on the ground wire has 'teeth' on the opening for the screw, so it needs no star washer....and yes, it's a good ground.

I never had any problems with the gas gauge, and never had the tank out.
Check the plug-in of the rear harness where it meets the intermediate harness and all other connections to make sure nothing is corroded or loose.

This will take a few lengths of wire -- but bypass all the OE wire connections in the car ... run new wire from gauge to sending unit. Also, make sure there is voltage at the gauge. Good luck!! TAZ

If you need to have the original sending unit rebuilt, John Wolf & Co. Inc. in Willoughby, Oh. is your man!! They do excellent work. They just rebuilt my original sending unit for my Impala.

Rich

Definitely voltage at the gauge, since it moves as I described above. And there should be no issue with the tan wire from the gauge to the sending unit, since when I ground that wire back in the trunk, the gauge moves from past full all the way to empty. If there was a break in that wire, I would think that would result in no movement of the gauge.

Rich, thanks for the lead on a rebuild if that's what ends up being necessary.

The problem with the sending units is usually it looses contact where the wire hooks on to the sending unit. Check continuity from the stud where the sending wire hooks up to the sending unit itself. The connection where it goes from one side of the sending unit to the other side goes bad. You can t6ake it apart and clean it