[TR] TR4A - Fuel Level Inaccurate

[Jonas Payne]

Ask Nissonger what resistance range they rebuilt the gauge for, there
are two generally accepted ones as far as I know, the numbers escape me,
but I believe they are something like  0-90 and 0-230 Ohms,

Your gauge needs to match the sender.

Also - in my experience, the sending unit is not good "out of the box"
you need to approximate / calibrate the sender by bending the float arm
to approximate the correct level in the tank.


Jonas Payne
PBR
Cell:   (702) 358-5084


-----Original Message-----
From: triumphs-bounces at autox.team.net
[mailto:triumphs-bounces at autox.team.net] On Behalf Of G.D. Huggins
Sent: Monday, January 16, 2012 11:17 AM
To: triumphs at autox.team.net
Subject: [TR] TR4A - Fuel Level Inaccurate

Listers,

Just a little over 1000 miles on the car.  Having lots of fun driving
and working on my "punch list".
One of the items on this list is that my fuel level is being reported
inaccurately.

I am currently ruling out the gauge itself, having had it reconditioned
by Nisonger as part of the restoration project.
I suspect the issue lies with the brand new, Moss-bought sending unit.
I know the sending unit is basically an electric potentiometer, so the
gauge is reacting to the electric "strength" it gets from the sender, as
the potential changes with the float arms movement.

My troubleshooting idea is to hook up a multimeter and take measurements
at both the sending unit and at the gauge, while forcing the float lever
all the way "full" and "empty".
I should see identical amounts of voltage from both places.  If I don't,
then I know something is happening in the wires connecting the two.

If the measurements are the same, then I should check the "empty" and
"full"
voltages against some known standard, to determine if the sending unit
is working correctly.
If it is with the standard, then my gauge is shot.  If its not, then the
sending unit is bad.

If the gauge is off, it going back to Nisonger to get it right.
If its the sending unit, then I guess I'll have to replace it.

Does this troubleshooting logic sound correct?
Is there something else I should do?

Thanks in advance!



Cheers,

Guy D. Huggins
1965 Triumph TR4A
CTC 63569LO

Online project diary at http://www.genfiniti.com/triumph

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