SW Wings gauges testing

I have wired up the water and oil temperature gauges and the gauge readings are too low / non existent. Using a multimeter there is a 12V reading at the ignition to ground terminals but only 2.4V between the ignition to sender terminals with 9.6V at the sender to ground terminals.

The fuel gauge has 12V but 4.6V and 7.4V instead, the fuel gauge seems to work ok.

I changed the water temp sender, put on a second ground strap to the block but no joy.

Any ideas?

Thanks for helping.
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PS Car is a 32 5w with a flathead.

 

did you use any sealant on the threads before you screwed in the senders?

 

I put some PTFE tape on the water sender then took it off as I realised it was acting as an insulator.

No tape on them now.

 

I am trying to figure out what you are saying here:

The fuel gauge has 12V but 4.6V and 7.4V instead, the fuel gauge seems to work ok.

12 volts should be available at all of the gauges from a typical 12 volt gauge wire out of the fuse box. If these wires are "daisy chained" off each other, start disconnecting gauges one at a time to see if a bad gauge/sending unit is dragging everything down.
If you don't see a change in voltage, and the 12 volts is available with the gauges dis-connected, then this wire or fuse has a bad connection. Try applying 12 vdc directly to the gauges from another battery.

It sounds like the capacity of the wire is limited and the simple load of a single gauge is pulling the whole circuit down. This is usually caused by a bad connection, pinched or damaged wire.

You might even find as the fuel gauge moves and adds more resistance to the circuit, the other gauges may also be effected.

 

Good call. I have daisy chained them so that might be causing it.

Thanks!

 

Do you mean "pinched", like when your little brother bends the yard hose over, then you look into the end to see what's the matter? I didn't think electrons could be stopped-up like that.

 

The gauges read ohms, not volts. Make sure you are not using any sealant as that can affect the reading. SW also reccomends using 16 ga wire. Pretty heavy in my opinion, but that is what they reccomend. Are you using the senders that came with the gauges?
A quick test:
ground the oil pressure, it should peg high
the water temp when grounded should go down to zero.

Mark