The MGA Guru website is still active and has been updated since I was there
last: http://www.mgaguru.com/mgtech/electric/fg_06.htm
There is a ton of good information there, including how to calibrate your
fuel gauge. I don't know if anyone was ever able to get their gauge
calibrated properly following the instructions, but not me.
I can get the gauge to work just fine on the bench and measure correctly in
accordance with the procedure at the website, but when I put it back in the
car it's off again. The procedure assumes that 68 ohms is the maximum
resistance seen by the gauge. I tried measuring the circuit resistance seen
by the gauge in my car and using that instead of the 68 ohms, but again the
gauge will work accurately on the bench but not in the car. The funny thing
is, my gauge worked reasonably accurately for years, until I changed my fuel
tank. I went through several Moss sending unit replacements until I
reinstalled the original sending unit. Didn't matter, the gauge is still
way off.
The MGA gauge is Jaeger, not Smiths. Otherwise the two gauges look
identical inside and out.
Steve Byers
HBJ8L/36666
BJ8 Registry
Havelock, NC
-----Original Message-----
From: healeys-bounces+sbyers=ec.rr.com@autox.team.net
[mailto:healeys-bounces+sbyers=ec.rr.com@autox.team.net]On Behalf Of
Alan Seigrist
Sent: Wednesday, August 22, 2007 6:24 PM
To: Warthodson@aol.com
Cc: healeys@autox.team.net
Subject: Re: [Healeys] fuel gage/sending unit
Gary -
You're really not supposed to adjust the guage readings by playing with the
float arm. You adjust the guage by ... guess what .... adjusting the guage.
This is from an old MGB website (no longer on the web but I know how to get
to it) and the writer's sage advice is:
*Adjustment
*There are 2 slotted holes that allow adjustment of the gauges. Unless there
is a sever inaccuracy, it is not recommended that any attempt is made to
adjust gauges because the two adjustment slots do not work independently
from one another. Adjustment of the slot nearest the low end of the gauge
tends to adjust the full scale reading, while that nearest the high end
varies the minimum reading. It will be found however that getting the gauge
to read correctly at one end also has an effect on the other. Adjusting the
other end then causes the original adjustment to change. Gauges may be
checked and adjusted by applying current from a 10 volt d.c. source through
2 watt resistors or a variable resistor of value shown in the table below.
The approximate resistance required to be in series with the gauge to
produce a given needle position is:.
<http://web.archive.org/web/20050208010348/>
*Gauge Reading*
Min.
1/4
1/2
3/4
Max.
*Resistance ohms*
320
205
120
85
55
Although he says not to adjust it... I might recommend that while your tank
is empty you adjust the guage so that it reads just at empty. That way at
least you will always know if you are close to empty.
Regards,
Alan
'52 A90
'53 BN1
'64 BJ8
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