30 replies to this topic

[micrawavewindow]

hi my temp gauge is always in the red and my fuel gauge is always off the chart when i have about atenner left in the tank it says full i think i need one of those stabailizer things

[stormintrooper]

hmmm no pressure eh?

[dklawson]

hi my temp gauge is always in the red and my fuel gauge is always off the chart when i have about atenner left in the tank it says full i think i need one of those stabailizer things

You may need a new voltage stabilizer... or not. They are electromechanical switching devices with internal contact points. If the stabilizer looses its earth connection (through its case) OR if the internal points stick closed, the stabilizer doesn't deliver 10V to the gauges but full charging system voltage. When the engine is running, that's close to 14V. At 14V your gauges will definitely read quite a bit higher than they should. However, if you have Smiths gauges, I would check and clean all the connections (including the mounting bracket) of your stabilizer before rushing out to buy a new one. New ones are not cheap and sometimes they are dead right out of the box.

[MiniMonty]

Re the fuel gauge, I remember reading (somewhere on this forum) that the float in the fuel tank which connects to the sender
unit often becomes "flooded" with age and clogged (therefore heavy) with crud. When the tank is full it will float (because even a
sodden float will have a touch more buoyancy when surrounded by the same liquid it is drenched in) but at a certain point the balance
tips and the weight of the float, arm and mechanism will cause it to sink quickly through the petrol in the tank.

This is why a lot of fuel guages read "full, full, full, EMPTY" with no gradation in between.
i.e. the float floats, floats, floats - then sinks like a stone because it's flooded, dirty and heavy.

Apparently it's pretty basic physics but I never listened at school so I have no clever answers.
But take a look in the cistern of your toilet to get the exact idea of how the fuel sender unit works.
(floating plastic ball connected to an arm gives feedback to another system - if the float is too heavy because
it's flooded or corrupted with rust, gunk or what have you the feedback is incorrect and the system fails).

But no jokes about toilets and floaters please

Try this LINK. before you start taking your clocks apart (they're really easy to break) !

Best wishes
Monty

[dklawson]

The sending floats do occasionally perforate and fill wholly or partially with gas. However, they don't float on a full tank and then suddenly sink. You are correct, it is physics, but there is no strange moment arm length or geometry changes that would mechanically, suddenly allow or cause the float to drop to the bottom of the tank after the level has dropped to a certain point. A float that is partially full of gas will typically present itself as a sending unit continually reading low (or empty) across its range.

The scenario of a normally dropping fuel gauge reading that suddenly drops to empty (full, a little less, a little less, empty) indicates a sending unit where there is a break in the internal resistance wires. Once the wiper inside the sending unit passes over the break, there is no longer a path to earth and the gauge stops responding (empty).

I have not seen a gauge that reads continually full, then suddenly empty. I can only speculate on what would cause that behavior.

[stormintrooper]

right folks...and DK...just got the chip and after iv had a cup of tea im going to whip my soldering iron out...test and take plenty of pictures of all the things that need doin and il make a new topic and request it be made a sticky one or whatever the correct term is

[stormintrooper]

Success! it has worked!

i will now upload all my pictures....and write down the process and post it in its own thread

unfortunately i have now been made aware that i either have a fuel leak or a dodgy sender

can anyone tell me roughly how much fuel hose goes between the tank to where it meets the metal pipe that bends around the front subframe?

[Mike92]

Alright guys update time!

Got the car back today, the garage did a thermostat and fitted another fuel sender unit, the garage said that the temperature gauge does indeed work its just that the engine runs a bit cold which is meant to be good.

However on the way back the fuel gauge did not move that much at all, probably as much as it did before.

So we know that its not the voltage stabaliser (there isn't one as it has NS gauges), we know its not the fuel sender as it has now had 3 and all have had the same reading, anyone got any ideas what could fix the fuel gauge problem?

Thanks,
Mike

Edited by PoweRMikE, 26 January 2010 - 05:09 PM.

[stormintrooper]

Check the FAQ section in interior..i made up a post that got posted by guess works about how to fix the NS gauges when the stabiliser dies, its a very simple little job and takes no more than 20 mins and will rule out gauge problems

[Mike92]

Check the FAQ section in interior..i made up a post that got posted by guess works about how to fix the NS gauges when the stabiliser dies, its a very simple little job and takes no more than 20 mins and will rule out gauge problems

Will do, thanks a lot mate

[dklawson]

Way to go Trooper! I'll be looking for the FAQ. It's good to know that the method worked and a fix is available to those who want to fix rather than replace their NS gauges !

[stormintrooper]

and it cost me...*drum roll* a sum total of £2 to fix

[MiniMonty]

Good stuff.
I love a happy ending !

[Jupitus]

Just a free bump and comment - I have been quite involved with working on stabilisers and mini wiring, and I read through Stormin's FAQ post (actually posted by Guessworks as a mod) and it's an excellent guide, in my view!

[Edmyatt]

I have a problem with my temp and fuel gauges on my 1984 mini. When i am sitting in traffic the the levels on the gauge seem to drop, when I get up to a decent speed they do up noticeably, by over a quarter. I though that its was just a dodgy reading from the fuel gauge and a sign that my car mini was over heating, but they change by such a drastic amount that Iam thinking it must be the gauges.
Any ideas on what part of the gauge system I should check first?
Thank you
Ed