[TR] Thanks & follow-up - Spit bodied GT6 fuel gage issues

[DAVID MASSEY]

Thinking out loud - I don't have a variable DC voltage device.  If I were to plug a DC output transformer (wall-wart, have plenty of those) into an AC variac (have) I should be able to dial in a desired DC output voltage - yes?   
 This will not work.  The wall-warts (plug-in DC power supplies) are voltage regulated and will put out a constant voltage over a range of input voltage.  Once you drop below a minimum it will just shut off.
If you can find 100 ohm variable resistor you can simulate the tank sending unit and test the gauge that way using a plug-in power supply.
It occurred to me recently that you could swap the fuel and temp gauges but I see you are way ahead of me.  Following up you can connect the fuel gauge to the temp sender and take a test drive and see if the fuel gauge reads in a manner similar to what you would expect from the temp gauge.
 
Dave 


 
 
-----Original Message-----
From: aribert neumann <aribertn at gmail.com>
To: triumphs at autox.team.net
Sent: Wed, Oct 12, 2022 10:05 pm
Subject: [TR] Thanks & follow-up - Spit bodied GT6 fuel gage issues

First thanks to Dave & Dave for the guess and confirmation that 67 ohm is in the ball park for the sending unit.  
Joel - thank you for the very informative fuel/temp gauge calibration sheet.  Looking closely at my Smiths gauges, there are double dots at the low, the midpoint and high - slight graphic variation but easy enough to work with.   I swapped the leads from the fuel to the temp gauge and now the temp gauge reads beyond full scale - that was a surprise!  Leads me to believe that I do not have a gauge problem.   I was going to double check the voltage at the gauge and sending unit. I did not realise that I did not have an analog voltmeter at home (could have brought one home from my workshop garage today).   It is starting to look like a wiring or voltage supply problem (even though the water temp gauge reads normal).
Thinking out loud - I don't have a variable DC voltage device.  If I were to plug a DC output transformer (wall-wart, have plenty of those) into an AC variac (have) I should be able to dial in a desired DC output voltage - yes?   

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