Fuel Gauge Issue

[Flyinace2000]

Still trying to get all my wiring back to 100% post restoration.  Got a strange issue with the fuel gauge.  If the engine is off and key is on, the gauge works. I can manually move the arm in the tank and i can watch the gauge move up and down.  If I start the engine the fuel gauge is pegged at full after about 1-2 seconds of the engine running.

More info:
https://goo.gl/photos/Y3wLVKFFNWnBnP4UA

Taking resistance readings with my electric meter (set to 2k) the readings were
Full tank (float near top): 0.03
1/2 Tank: 0.250

Voltage readings in line with the green wire and the sending unit were as follows
Ignition On / Engine Off: 9.62V
Engine Running: 13.49V

[MiniDave]

Do you have the newer style sender? I'm told there is some incompatibility with these and the volt stabilized gauges. One thing you might try is to run a separate 12v wire to the + side of the gauge, instead of having it run off the lower voltage post stabilizer.

I'm not responsible if you do this and it burns up the gauge!  ;D

I installed one of these newer senders in a car this week and the gauge does exactly the same thing, but I didn't get a chance to sort it out.

Edit: after looking at your pic...

Wait a minute, yours is wired differently - mine only had the hot wire and the ground......I'm not sure what the white wire is for on yours......need to look at a wiring diagram first.

[Flyinace2000]

Do you have the newer style sender? I'm told there is some incompatibility with these and the volt stabilized gauges. One thing you might try is to run a separate 12v wire to the + side of the gauge, instead of having it run off the lower voltage post stabilizer.

I'm not responsible if you do this and it burns up the gauge!  ;D

I installed one of these newer senders in a car this week and the gauge does exactly the same thing, but I didn't get a chance to sort it out.

Edit: after looking at your pic...

Wait a minute, yours is wired differently - mine only had the hot wire and the ground......I'm not sure what the white wire is for on yours......need to look at a wiring diagram first.

I forgot to mention that I have a 73 Innocenti Mini 1001.  The white wire goes to the low level warning light.

Here is a link to a wiring diagram that is mostly the same as my car (i have a difference dash)
https://dl.dropboxusercontent.com/u/2987482/Innocenti/wire-inno%20Model%20(1).pdf

One more bit of info, when i turn the car on the "GEN" light stays on (like its not making enough power right away), but after a quick blip of the throttle the light goes off and at the same time the fuel gauge pegs at full.

[MiniDave]

That's normal for the gen light (do you have an alternator?)

[Flyinace2000]

Yup, alternator and negative ground

[Flyinace2000]

Here is what the sending unit looks like (via Ebay)

[Flyinace2000]

Got it fixed.  The wiring diagrams all show the 12V ignition lead to go to the fuel gauge first and then the temp gauge.  But on my car it has to be reversed. 12V to the temp gauge then a Y split that goes to the fuel gauge and low level light.  Not sure why, but once i did that everything works.

[MiniDave]

Excellent! Hope that fixes my friend's car too then.....