7 replies to this topic

[MatBat]

Hi there,

I have a 1996 Spi equinox and I'm trying to install a 52mm fuel gauge as I have a custom dash.

So far I have tried one supposedly from a Robin Reliant (this one gracefully sweeps up to the full mark even though my tank is half empty)

and an "AC Made in England" brand one supposedly working off a Mini off with the numbers 7228165H58 (this one does nothing, zip)

So before I get cross at eBay sellers am I doing something drastically wrong?

All I ask is to know when my car is going to run dry!!


Many thanks in advance

[dklawson]

I have no way of giving specific advice on the gauges on a car as late as 1996. However, there are some basic things you can do.

In the boot you should find two wires connected to the tank sending unit. Mark them for position and disconnect them. Hook a multimeter to the two terminals on the tank and set the meter to read Ohms. Use a bent coat hanger or other heavy, stiff wire to fashion a hook like a fireplace poker. Use that through the gas tank filler neck to lift the float ALL the way up to the top of its travel, then push it all the way down until it's at the bottom of travel. Record the resistance values at both extremes.

On cars from late 1964 on (presumably including yours but I don't know for sure) you will get NOMINAL values close to 240 Ohms = Empty, to 30 Ohms = Full. If that's what you find, gauges from cars like later MGBs, MG-Midgets, and most Triumphs will work. I can't comment on Reliants.

The sending unit should have a black wire on it for an earth connection. The other wire should be green/black and that goes off to the fuel gauge. The remaining gauge terminal MUST (repeat: must, must, must) be supplied with 10V. That's 10 volts, not full battery voltage. On original installations using the 52mm gauges this is handled by a separate component called a voltage stabilizer. (Use search on this board. There have been many threads on the topic including one earlier this month). IF you have hooked the gauge DIRECTLY to your car's 12 V supply and NOT used a voltage stabilizer, the gauge IS going to read high... as much as 40% too high.

Let us know what you measure and how you've wired things up so far.

[phil hill]

<snip> The sending unit should have a black wire on it for an earth connection. The other wire should be green/black and that goes off to the fuel gauge. The remaining gauge terminal MUST (repeat: must, must, must) be supplied with 10V. That's 10 volts, not full battery voltage. On original installations using the 52mm gauges this is handled by a separate component called a voltage stabilizer. (Use search on this board. There have been many threads on the topic including one earlier this month). IF you have hooked the gauge DIRECTLY to your car's 12 V supply and NOT used a voltage stabilizer, the gauge IS going to read high... as much as 40% too high.

Let us know what you measure and how you've wired things up so far.
</snip>

Having fitted an early smiths type fuel gauge on a mini I'd say for certain you need a separate Voltage Regulator as Doug describes.

The later cars don't have a Voltage Stabliser on the gauge pack, and so far as I know the tank sender units have never changed, so the later gauges must be different and rely on full voltage rather than 10v from the stabliser as per the earlier cars.

Anyway, the long and the short of it is you need a voltage stabliser for this type of gauge to work correctly.

Phil.

[daemonchild]

<snip> The sending unit should have a black wire on it for an earth connection. The other wire should be green/black and that goes off to the fuel gauge. The remaining gauge terminal MUST (repeat: must, must, must) be supplied with 10V. That's 10 volts, not full battery voltage. On original installations using the 52mm gauges this is handled by a separate component called a voltage stabilizer. (Use search on this board. There have been many threads on the topic including one earlier this month). IF you have hooked the gauge DIRECTLY to your car's 12 V supply and NOT used a voltage stabilizer, the gauge IS going to read high... as much as 40% too high.

Let us know what you measure and how you've wired things up so far.
</snip>

Having fitted an early smiths type fuel gauge on a mini I'd say for certain you need a separate Voltage Regulator as Doug describes.

The later cars don't have a Voltage Stabliser on the gauge pack, and so far as I know the tank sender units have never changed, so the later gauges must be different and rely on full voltage rather than 10v from the stabliser as per the earlier cars.

Anyway, the long and the short of it is you need a voltage stabliser for this type of gauge to work correctly.

Phil.

Personally, I'd get the right bits and then mock it up in the boot of the car with some pieces of chop block.
Easy access to battery, good earth and the tank sender.
When I know i've got a working config, I'd transplant it to the dash.

If it didn't work then, I'd suspect the electrics between the sender and the gauge.

ps. Yep. I know, no fuses.. (use an inline one??)

Edited by daemonchild, 20 February 2009 - 02:21 PM.

[MatBat]

Many thanks, I was just running 12V so I'll get a regulator to make it 10v, will I have damaged the gauge putting 12v though it?

Many thanks again!

[dklawson]

12V through the gauge for a short time will not damage it. 12V for a long time can overheat the internal resistance wires and shorten the life of the gauge.

Voltage stabilizers are available from many sources. If you start a new thread asking about buying one, a couple of people on the board can sell you a homemade, solid-state one for very little money. The advantage of the solid-state one is that they are inexpensive, easy to conceal, and are not mounting position sensitive. The Smiths electro-mechanical ones MUST be mounted the correct way to work accurately.

[Jupitus]

Yup - Solid state stabilisers from me for £5 posted

[Jupitus]

Actually, having posted this I knew I had to order some new bits for making these up, and I think I might actually be making a slight loss, so after this one (if required) the price is going up to £6 posted, FYI. Sorry