Fuel gauge problem?

[m3evo321]

Hi guys. 1967 post prod tourer. The fuel guage is reading about half a tank below what it should. ie when tank is full only reading half , when tank is half only reading empty. Also I have just fitted a temp guage which reads very low . Might the voltage regulator be at fault & how do I test it?

[Cam]

It's quite possible that the regulator is faulty. Measure the voltage coming from the regulator to your gauges with reference to earth and if it's much lower than around 12v then your regulator is duff.

[minor_hickup]

I had this, it was the fuel sender unit that was at fault. Only discovered this after 2 new reulators.

[Cam]

That's a possibility but I'd check the regulator first if the temp gauge also reads way too low as they should have the same feed (the regulator).

[Willie]

Take the lead from the sender unit and short it properly to chassis(earth)
NOT on the tank and if the reading becomes more accurate your tank is
not a good connection to the chassis.

[Packedup]

IIRC you should get system volts in, and 10v out of the stabiliser - Any less than 10v and it's probably that. As both guages are reading low then it's certainly the most likely culprit.

The handy thing with Minors having the stabiliser tucked away is you can get one of those slightly half finished looking solid state ones off Ebay for less than a tenner and not have it looking a bit naff

Of course, poor earths, or failing senders could also be the problem, so it's worth doing the sort out test to be sure, though most cars will benefit from a new stabiliser anyway after all these years...

[m3evo321]

I have an output from the stabilizer which is dramatically fluctuating between 2 & 8 volts so I guess I need a new one!

[Cam]

Sounds like it.

My '63 car doesn't have one and you can see the fuel guage get a slightly higher reading when driving as opposed to being stationary. It's not enough of a fluctuation to cause a problem though.