Gauge Problems

[december2017]

I have contacted you before regarding my 1970 MGB, and you have been very helpful. My problem this time are the fuel and temperature gauges. They float, the fuel gauge from empty to the true reading and the temp from normal to cold and back. The car is running great and no problem with over heating. I would appreciate your thoughts.

Brian Bebelman
Catelgar, British Columbia

[Art]

The first step I would advise would be to check all the connections to the gauges, particularly the ground, which may be common to both.

They do loosen up and it's a fairly common problem. It's tight getting to the backs of the gauges, but it might remedy your issue.

Hope that helps.
Safety Fast!
Art Isaacs

Editor's Note:  The problem was solved by tightening a loose voltage stabilizer.

[september2018]

This was posted in Dec. 2017, 10 months ago and has over 700 "reads".  Tells me instruments are a topic of interest.  I just got my ol' 1974 B back and have trouble with the gas gauge not registering, so I installed a new sending unit.  Simple, and the float in the old sender had gas in it. Thought I had solved the problem, but the gauge still wouldn't register.  Removing the new sending unit I found gas in the NEW plastic float. There is a small crack on the shoulder of the groove where it fits in the wire arm.  I manually operated the arm of the sending unit,  the new gauge registered no more than a half tank. Too much resistance in the wire between the gauge and the sending unit?  I will try a new connector.   Ordered a new brass float, but why doesn't the sending unit allow the new gauge to register full?  With about 6 gallons of gas it registers a quarter.  Now I am thinking it may have one of those new, larger tanks!  When I re-reinstall with the new float, I will fill it up and see how much it takes and what it registers, and measure the volts from the voltage stabilizer to see if it is putting out a full 10 Vts.  But the speedometer is wildly optimistic!  At 65 MPH per a GPS, the speedo registers 80 MPH!  The speedo is not connected to the voltage stabilizer.  Must I send the speedo out for calibration?

Replaced  leaking plastic float #2 with a brass one, tightened the connector, and its registering about the amount of gas it should, at over 1/2 tank. (I checked voltage to the fuel gauge and its just over 9.9 volts.) Fixed for now!  Lesson, don't trust those plastic floats.   Speedo is still overly optimistic.