Do you need Ammeter /Fuel gauge to start car

[Hayden]

I removed by faulty Ammeter/Fuel gauge.  Ammeter was fine but the fuel gauge never worked.  I changed out the fuel tank float and checked the wiring first, its the fuel gauge.  I removed the gauge reconnected battery, car won't start, no power at all.   Do you need the ammeter connected? Couldn't fine any topics on how to bench test a fuel gauge.

[zKars]

As long as you joined the ring terminals that were on the ammeter posts, then everything should work just fine. 

If you left them separated (and insulated I hope!) then ain’t nothing going do much of anything. 

Edited October 17, 2021 by zKars

[SteveJ]

You have to be careful bench testing the fuel gauge. From the positive wire going through the gauge, there are two paths. One goes to ground, and the other goes through the fuel gauge sending unit and then to ground. Some people don't ground the first path and ruin the gauge.

Power for most of your circuits goes from the battery to the ammeter and then down to the various circuits. (The brake light circuit is a notable exception.) If the wires at the ammeter are not going through the ammeter or not connected to each other, you're not going anywhere. As @zKars warned, if not using an ammeter, you have to insulate the connection between the two wires well, or you may end up with a smoking pile of rubble.

[Dave WM]

the assumption is you have a ammeter with an internal shunt. Later models like my 75 used as external shunt, in which case no need for an ammeter connection to complete the circuit.

[SteveJ]

26 minutes ago, Dave WM said:

the assumption is you have a ammeter with an internal shunt. Later models like my 75 used as external shunt, in which case no need for an ammeter connection to complete the circuit.

He said the car won't start without the ammeter. That says it is not one that relies upon a shunt.

[Dave WM]

Or there is something else that went wrong at the same time, I don't like to assume. I think a model year would be helpful.

[Hayden]

Good to know, I should have mentioned the year.   My car is a early 1973 240z.  I started the car then turned it off and disconnected the battery to remove the gauge.