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Triumph TR6 - Electric gremlins.

Hi,

I need some help sorting out a problem.

The fuel gauge will indicate "half full" when the tank is in fact full. As the level drops it will indicate this below a half tank.
However I recently had to remove the speedometer to service it and lo and behold the fuel gauge then indicated a full tank.(TANK WAS FULL).The temp. gauge also read hot i.e. full deflection.
This probably has something to do with resistance but autoelectrics is something of a dark science to me.
Logically it appears that the fuel gauge does work and the problem is probably the sender unit in the tank.
However any suggestions would be helpful.

'73 TR's rule.

Regards, Neil Peniston.
Neil Peniston

Hi Neil,
My first guess since you are having trouble with the fuel and temp gauges is your voltage stabilizer as both are fed from it. Using a meter or a test bulb test the stabilizer on the light green wire, the voltage should be 12 volts and it will pulse.
If your temp gauge is always showing hot then that could be a short in the wire from the sending unit or the sending unit itself, it's located near the thermostat so unplug it and with the ignition on see if the gauge drops back to cold..if so then its the sending unit. If you short the wire you just unplugged against to ground ( against the block will be fine ) it will go to full hot that will tell you the gauge is good.
I assume the gauge moves to the cold position when the ignition is off? if not then the gauge is faulty.

The same theory applies to the fuel gauge but it might be a ground problem since it finally worked.




Charlie
Charlie B.

Hi Charlie,

Thanks for the reply.

The temp. gauge only shows hot when all the wires at the back of the speedo are disconected otherwise it works perfectly.
Both gauges return to zero when the ignition is off.
Neil Peniston

Neil
You kinda answered your own question.
Everything worked before you touched the spedo, now it does not...well acts differently than it should. It will not be the sending unit. Charlie is pointing you to your problem. Both the temp and fuel gauges are "voltage stabilizer" through the... yup you guessed it... the voltage stabilizer (VS). The VS is attached to the back of the spedo. The attached schematic image shows a 1973 VS. the only difference is pre '73 the output side of the VS (terminal I) was a light-green/green wire as compared to '73 to '76 it was a solid light-green wire. Very early I think had a ground wire terminal. Later, the Case of the VS is ground. Terminal B is obviously at 12V supply.
Make sure you have wired it up correctly and that the terminals are clean of corrosion. Dielectric grease is always helpful. Make sure it is screwed tightly to the spedo as this is ground. If I recall the spedo also has a ground (black) wire attached to it from the wring harness.
Rickc

Rick Crawford

Thanks for the info. Probably is a ground issue.
Neil Peniston

I had the sdame problem and replaced the VS with a modern electrical (semi-conductor) version from E Bay...and no problems since, I think it was about 7 dollars so a good investment (www.freewebs.com/classicstabalizers/)

bob
Bob Craske

This thread was discussed between 15/03/2008 and 22/03/2008

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