Fiat Dino Forum (FDF)

Happy holidays to all on the forum! Let's move on to a better 2021. My question is about the fuel tank sending unit, specifically on a 2.4 spider. The 2.4/2.0 coupes and 2.0 spiders may fall under this question as well, but I have not researched their specific wiring diagrams. The wiring diagram I have shows the two wires that attach to the sending unit, one controlling the low fuel indicator light and the other driving the gauge. The wiring diagram also shows the sending unit going to ground. All makes perfect sense. In my car I had to deal with some seepage at the tank so I removed the tank for repair & re-coating. All good. While the tank was out I renewed the rubber on the tank straps and body of the car to prevent any metal on metal contact and/or chafing. So..... the fuel tank is essentially isolated (electrically) from the car body. There is no ground wire that I am aware of from the tank or sender that would complete the fuel tank sending unit circuit. Easy problem to solve, but what has me scratching my head is what mechanism did the cars use from the factory to ensure the fuel tank sending unit is grounded so the gauge and warning light would be functional? It seems the all encompassing, Italian car electrical diagnosis applies here.... IAABG (It's Always A Bad Ground!) Just curious what the thoughts of others are on this issue.

Social distancing is best performed at 6000 rpm on a nice sunny day........

Hi, I just took the tank out to access the differential, and there is a ground wire that connects to one of the bolts that holds the tank straps. The ground for the fuel pump was also attached there (at least, on my 2400 coupé). The spider is likely different, but this could be a starting point for you.
Best wishes for the holidays and great motoring next year!
Dairo

Thanks for the reply. Likely a ground wire has gone missing somewhere along the line. Easy enough to add back in. Cheers
Charlie

Absolutely right. There is a ground wire attached to one of the small bolts of the fuel tank sending unit. By the way: 2.4 Liter has a fuel return line from the carbs and is therefore different than the (at least early) 2.0 Liter versions.

That's exactly what I wound up doing. A ground wire from one of the fuel sender mounting bolts to the body took care of it. Cheers.
Charlie