Faulty Fuel Guage

[kjm]

The guage on my car reads high so I bought a new sender unit at the National,thinking it was at fault, but no change when fitted.I then tried a second hand guage I had, this reads even higher, should a new guage solve the problem ? or is there anything else that can go wrong ?

[bmcecosse]

Gauge surely......... Battery voltage reversed polarity? Wrong type of gauge / tank sensor? Not wired through the 10 volt voltage stabiliser (later black face hot wire gauges ) ???

[beero]

You could trace the wire back from the sender and make sure all contacts are good. Any extra resistance in the wiring will put the reading out. Later cars had a voltage stabiliser to feed the gauge and that could be at fault.
The gauge is adjustable but shouldn't have gone out of adjustment unless it was removed and dismantled. Don't know how to adjust it accurately, someone else may have info on this.

[bufferzone]

The fuel gauge on my 67 read high (ran out of petrol with needle showing quarter tank left) so looking at the gauge I found a tiny slot at the back of it, and with a small screwdriver I adjusted the needle down to empty. fixed.

[kjm]

Thanks all, think I will try a new gauge, its for my daughters 65 car

[cheezy_munkey]

As BMC says, make sure you've got the right sender for the gauge. That was the problem with mine. A previous owner had fitted a sender that wasn't compatible with my speedo. Took lots of fiddling about and loads of posts on here before I discovered that that was the problem.

[bmcecosse]

A 'new' gauge is going to be costly - don't rush in to that till you have checked out all the other low cost/free possibilities! Not wired through the 10 volt supply is the most likely problem. It should be a black face gauge - a 'hot wire' instrument - when you switch on from cold it should slowly move across the face from left to right....... Does it?

[kjm]

yes it does move slowly from left to right when ignition is switched on,just keeps going as far as it can,way past full,it is the black one.Tom Roys stall didnt ask for year or colour of gauge when I bought the sender.

[MarkyB]

That sounds like a gauge expecting 10 volts getting 12 volts instead.

[bmcecosse]

As I said earlier - check it's wired through the 10V stabiliser!