new sending unit flutter

[wwheeler]

Wanting to know what direction to head concerning the fuel gauge fluttering. The fuel gauge was just recently rebuilt as part of the dash rebuild and has been working very well. No other instrument related issues. Sending unit (new tube style) was replaced about four years ago. The gauge flutters (1/8 tank variance at the max) when driving, sometimes idling but never flutters with just the pump on engine not running.

I checked the plug on the unit and looks good, no corrosion. With the sending unit still in the tank, there is resistance between #1 and #2 prongs and will fluctuate when jiggling the car back and forth. It is steady when not moving. I am leaning toward removing and trying to flushing the sending unit and also checking to see if the disc at the bottom is still there. If that doesn't work, maybe replace the sending unit??? The dash is totally assembled and would rather not tear it apart for testing unless absolutely necessary.

What do you think?

[waltklatt]

Wallace,
You mentioned the fuel gauge was rebuilt.
Might be that they left out the bottom 'maze' pattern plastic piece.
Take it apart to see that the pieces are all there and in the proper order.  The metal disc cap on he bottom should be flush against this maze plastic piece.
Reason for the maze is to slow the inrush and outrush of the fuel through the small pinholes, hence your fluctuating gauge needle.
Walter

[Tyler S]

I had the same issue and it turned out to be a loose pin in the electrical bulkhead (handshake) connector by your left knee. Give that a jiggle.
But your fluctuating resistance reading on the sending unit points twards a dirty sending unit.