Gas gauge does not go all the way to FULL

[92rrrandall]

Not the end of the world but 1981TR8 gas gauge does not go all the way to FULL. Recently had to fix leaks in gas tank, so I installed a new sending unit for the gas gauge at the same time. New sender had no effect on how the guage on how the dash reads.

Randall

[john]

have to only agree with this one both mine never say completly full

[8 whole cylinders worth of punch to ram the world through the windshield and out the rear view mirror. Car & Driver]
1981 Grinnall TR7 v8
1981 Black FHC
1979 & 1980 Black Premium FHC(laid to rest) Sorry


John

[Wayne S]

Nor mine .......

<b>2.0 Litre DHC Grinnall
Red 4.0 Litre V8 DHC Grinnall (with huuuuuge arches...!)</b>

[FI Spyder]

Our gauges work on the basis of a potentiometer (variable resistor) effecting the volts/amps going to the gauge. That means any resistance introduced into the circuit by way of corrosion (white corrosion, rust, dirt) will effect the way the gauge reads. To get a correct reading on any gauge this extraineous resistance must be eliminated. Every place the the wiring has a connection in the circuit, were it is attached to a spade connector, where the connector is screwed or pushed onto the guage or sender can introduce resistance into the circuit the the gauge will not read as it should. If this is the case, changing the senders and gauges will not fix the problem unless the act of changing them is what makes a clean connection.

My gas gauge reads full when full but it does use a different sender than carb TR7.




TR7 Spider - 1978 Spifire - 1976 Spitfire - 1988 Tercel 4X4 - Kali on Integra - 1991 Integra

[PeterTR7V8]

My fuel gauge is the same. I'm thinking that the float tether is too long & is not allowing the contact arm to go all the way to the top of the resister matrix. I could bend it but then it would still read 1/4 full when it was empty. I'm assuming that the float arm is hitting the tank ceiling & restricting the angle it can point upwards when full.


Never say die. At least not while you're still breathing.

[jclay (RIP 2018)]

Mine used to go to 3/4 and stop. When I installed the Odd LED lights, I replaced the gauge with a new one. Now it works great!

jclay

[url="http://web.mac.com/jclaythompson/iWeb/Site/Welcome.html"]My Triumph Site[/url], [url="http://web.mac.com/jclaythompson/iWeb/Technical/Intro.html"]Technical Stuff[/url], [url="http://homepage.mac.com/WebObjects/FileSharing.woa/53/wo/HJMTK8gsojtwKleP.1/0.2.1.2.26.31.97.0.35.0.1.1.1?user=jclaythompson&fpath=Triumph_Articles&templatefn=FileSharing4.html"]Download Page[/url]

[bottomtop]

There's a thing I bought that looks like a texta and is called a "de-oxit pen" I used that on the dash printed circuit board on all bits that made contact with other bits (technical language I know). It certainly made the dash lights brighter, I wonder if might help make electric gagues work better too if they have contact points there (I don't remember if they do). I was worried to use normal spray on contact cleaner because I didn't know if it would corrode the printed circuit so i was careful to use the pen only on the metal contact points.

[92rrrandall]

Thanks for replys. Interesting to see that many others are having the same "problem".

I did thoroughly clean all the connections when the new sender was installed...and there was no difference at all in the way the fuel gage reads. So I now assume problem is in the dash.

Also just looked it up in the shop manual. That has a good description of how the gauge works. There is a "calibration resistor" inside the gauge which might could be changed to give the correct reading. Not having much luck finding a new fuel guage.

Randall

[MickeyR]

Randall -

Is the needle movement "symmetrical"? That is, when it's fully left, is the distance equal to fully right? You'll have to move it gently with your finger (or better, a toothpick) to check. Mine was off a bit, so I "persuaded" it, and now it "appears" more accurate.

Mind you, I don't depend on the gauge. Learned THAT lesson long ago! I fill up based on mileage, and rarely go much past 220 or so.

Mickey

[Odd]

My fuel gauge just barely makes it to the 4/4 position,
and in just a few (~80km/50miles? or so) reach the 3/4 position. On comparison the distance driven from 1/4 down
to 0/4 is way longer, say 150-200km. I've chalked all of this up to the potentiometer winding in the sender not being
correctly designed to give a linear (and thus symmetrical) behaviour of the gauge. Something I have to live with...

I drive the car, keeping a casual eye on the fuel gauge, and when it reaches ~1/4 I start to keep an eye open for
the low fuel light lighting up. When the light <u>lights up constantly</u> it's time to drive into a service station within the
next 30-40km. And fill it up, full of course! Filling it to the full then usually is 45 to 50 litres. I've never been able to get
the full stated 55 litres into my tank btw. I once (to test how it feels and when it dies out of fuel starvation) drove
it seriously coughing into a service station (and with the efi pump sounding like it was rather 'unwell' and struggling)
and couldn't squeeze more than 51 litres into the tank. I guess the US type emission/evaporation equipment is
limiting how high up I can fill the tank <u>and</u> the efi surge pot etc aren't allowing me to empty the tank fully.


<font color="red"><b>My two 1980 Wedges...</b></font id="red">

[Underdog]

Mine also reads 3/4 when full. I've just become used to it. FWIW.

Jim Underwood
72 MGB BRG
80 TR8 Persian Aqua
If women don't find you handsome, they should at least find you handy.

[Rich in Vancouver]

Mine goes to about 7/8 with a new replacement sender. Bending the needle may be the way to go as I am not about to pull the sender again as it isn't leaking and I don't want to tempt fate!

Cheers,
Rich

1975 TR7 ACL764U

[chan]

I'm with Mickey on this problem. My first 7 had the same problem and i spoke to Simon at S&S and he told me the trick of moving the needle on the guage. You can actually feel the point where the needle stops but it just needs a little nudge past that point and it should work a treat.

Colin

[92rrrandall]

All of a sudden I have the opposite problem. The gauge goes almost to full, when full. But now 1/4 means empty. As in stranded in the middle of nowhere 300 miles from home empty.

I have verified this with several fill-ups. My gauge changed the way it measures over the course of one day. Must be the float because the low fuel light does not come on at 1/4, but the light does work.

Randall