Odd Fuel Gauge

[saabfast]

I know they tend to be on the 7 but, having finally fitted a working gauge last summer, I now find on starting after the winter layup that it registers but also very slowly cycles up and down continuously about 1/8 to 1/4 of a tank about the 1/4 full point (which I assume is the current tank contents).
Over the winter I have had the dash out to fit LED backlight bulbs and cleaned all the contacts. I have also fitted a 'new' alternator which gives a much better charge (just in case any of this is relevant). Can it be the voltage regulator (is this the small 'block' bracketed to the instrument perspex cover screw?), or are there any other ideas?

Alan
Saab 9000 Stg 1
'81 TR7 DHC

[Henk]

The block which you at referred is the relais for low fuel warning.
Never heared of a voltage regulator on a tr7.

Henk

1980 TR7 US Convertible
1978 Mini Clubman Estate

[Odd]

Alan,
the little block is a time delay unit for the low level warning light. It comprises an electrically heated contact point that starts to heat up and bend when the contacts in the tank sender unit are closed - but if this is just a short slosh the amount of heat isn't enough to close the lights contacts, for this a low level of longer duraton, typically several seconds, is needed. Saves us a blinking low level warning light...

PS
It's not an Odd gauge - possibly it's an odd gauge... [;)]

/Odd

[saabfast]

OK, apologies Odd, should have said 'Eratic fuel gauge'!
Its good to know what the 'block' is, I thought instrument clusters normally had a voltage regulator/stabiliser to allow for the variable charge/system voltage?
However, any ideas why the gauge should slowly go up and down continually?

Alan
Saab 9000 Stg 1
'81 TR7 DHC

[John Clancy]

My own gauge varies dependent on going uphill or downhill. Also when cornering the gauge can flutter a bit. It's all down to the ballcock in the tank floating around and can give the guage at least 1/8th of a tank difference in the reading.

<center><b>[url="http://www.triumphtr7.com/documents/sales/codenamebullet.asp"]Buy the story of the Triumph TR7/8 on DVD here[/url]</b></center>

[Odd]

<blockquote id="quote"><font size="1" face="Century Gothic, Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"> I thought instrument clusters normally had a voltage regulator/stabiliser to allow for the variable charge/system voltage? <hr height="1" noshade id="quote"></font id="quote"></blockquote id="quote"> Maybe so, but in the Wedge they used instruments with self stabilising coils that don't need a voltage
stabiliser. It's as accurate (or inaccurate!) at 14 volts as it is at 9.5 volts by virtue of the air core coils in
the instrument... Quite clever design actually...

[john 215]

Hi,
Worth checking the connection at the tank unit, these have a habit of corroding. Also make sure that you did'nt accidently damage the printed cicuit or leave the connection loose on the back of gauge.
Cheers John

LIVE LIFE A QUARTER OF A MILE AT A TIME!
1979 3.5 FHC(STATUS PENDING!!)

1982 2.0 DHC NOW A 4.6 WILL BE ON THE ROAD VERY SOON!
Read My Blog http://www.waringstowntr7s.co.uk/blogs/ ... hp/John215

[saabfast]

A little more peculiar today. I was running the engine to warm it for an oil change and watching the temp gauge. When I revved it the temp gauge suddenly dropped, with the fuel gauge following suit. When the throttle was released both went back to reading. I 'exercised' the spade connection on the temp sender and it all went back to normal, including the fuel gauge!
Don't you just love the challenges of Lucas/BL electrics (also had to sort the hazards on my sons Mini today).
I will check the sender connection on the tank tomorrow.

Alan
Saab 9000 Stg 1
'81 TR7 DHC

[Rich in Vancouver]

Bad Ground on the panel maybe?

Rich

1975 TR7 ACL764U

[FI Spyder]

Oxydation + dried grease + dirt + air polution + acid rain + electrolysis + water + salt + 30 or so years = lots of interesting problems. Clean them all.

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

[Odd]

I'd recommend a separate (heavy gauge, say 2.5 sq mm) wire connecing the essential earth points
on the rear of the cluster together - and then going to a good earthing point on the body.
Should relieve you of most earthing related problems at the instrument cluster.

[saabfast]

I was thinking the same Odd, just after I screwed it all back together. Too cold to go back today so will see how it performs when I put it back on the road next month.

Alan
Saab 9000 Stg 1
'81 TR7 DHC