uel gauge gets stuck beyond full sometimes ??? 93 Maxima

Banker

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So the gauge is accurate sometimes, then jumps way past full as far as the needle will go (WAY past full). The car has a around 3/4 tank and the sending unit (float) is good. I can test the resistance at the harness that comes out of the fuel pump / sending unit and it reads 14.5 ohms which is consistent with the chart in my Alldata manual. here's the chart:

Full tank: 4-6 ohms
Half tank: 27-34 ohms
Empty tank: 78-85 ohms


when the gauge is functioning properly and I disconnect the harness the needle drops to empty as I suspect it's suppose to (is this correct?) when the needle is pinned, unplugging the harness has no effect. when the gauge is working I can jumper the pins on the gauge side of the harness with a paperclip (less than one ohm, which simulates a full tank) and watch the gauge go from 3/4 to full.


why i think the sending unit is working properly: even when the gauge is pinned at overfull, i can backprobe the harness and read 12ish ohms. or i can disconnect the harness (which should cause the needle to drop to zero but it stays stuck at pinned) and still get the correct 14.5 ohms.


even weirder, this gauge RANDOMLY goes from working to pinned overfull and randomly back regardless of heat or vibration or anything. I had the car key on, engine off and watched the needle pin at full. only thing that might affect it is cycling the key on and off cuz that's all we were doing. but hard to tell cuz its not easily reproducible either working to not working or the other way around. it does spend most time not working.

so this must be a wiring or gauge problem I guess… but why is this happening and which one is it? im just not an electrician and I don’t understand.

these are the analog gauges of course. all other gauges work. plz don’t say anything silly about "well my car reads a bit past the full line when I top it off" cuz that is not what's going on.
 

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