Gas gauge

[John Morralee]

The car is a '63 BJ7 and undergone a complete restore after'rusting out'and standing idle since 1973 1)Gas gauge does not work. 2)There is a slight deflection of the needle when ingnition is switched on i.e current is arriving. 3)The sender in the tank shows a change of resistance when float is operated by hand.4) I understand the balanced coil principle of the gauge(sort of!). Is it worth taking it apart? Can they be repaired?

 

[Dave Russell]

Hi John,

I would suggest that you go here & look the situation over. Then you can decide what to do. Step through the sections by using the arrows at the bottom of the page. Although it is for an MG, the Healey gage is the same.
https://mgaguru.com/mgtech/electric/fg_01.htm
D

 

[Mac]

Be sure to take the sender unit out of the tank and make sure that the float does not have a leak. I had one that had filled up with gas and read empty. I, of course didn't figure that out, until, in my infinite wisdom, thought it was the guage. Took the guage apart, screwed that up pretty good and had to send it off for a rebuild. Finally took the float out, saw that it was filled with gas. Oh well, its just money, right? mac

 

[ThomP]

Dave

That page is a great find. We should ask Basil to build a page with technical links like that. I know Jim Warner has a page on his site, but why not in multiple places.

 

[RF Thom]

Check the gauge itself. Disconnect the power lead from the sender unit the gauge should read empty. Use a jumper and ground the wire that attaches to the sending unit - the gauge should read full. Also make sure the sending unit has a good ground. I just went through this with my daily driver. This time the fuel pump stopped - no go. As usual I had just filled it to the limit anticipating going to my daughters. I emptied the tank - not easy, dropped it down took the sending unit & pump out only to find when disconnecting thewire harness the ground terminal corroded away where the wire is inserted into it. Repaired it easily and put it all back together - most of a day waisted over a broken ground.

Regards, Bob

 

[Dave Russell]

<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by RF Thom:
Check the gauge itself. Disconnect the power lead from the sender unit the gauge should read empty. Use a jumper and ground the wire that attaches to the sending unit - the gauge should read full.
Regards, Bob<hr></blockquote>
Unlike most newer cars, the Healey & MG gages are backward from this. The sender should measure around 70 ohms at the full mark & nearly zero at empty. Lifting the wire should make the gage go above full. Grounding the wire should read empty.
D

 

[Stretch]

Also check for a good connection from the sending unit to the car body. The continuity within the sending unit to its own body and/or to the car's frame can be a problem. It often causes erratic gauge performance.

 

[John Morralee]

Gas gauge: thank you all,will get to work(will be happy to throw my 'gas tank dip switch'away!

 

[John Morralee]

that should be dip stick!

 

[John Morralee]

well I have done most of the reccommended procedures with no result!There is a distinct needle movement on switching on ignition (from stop to 'Empty'.12volts is at the gauge 7.5 at the sender.Float does not leak.Resistance changes as float moves (as well as I can read on a fluctuating digita V/meter)from .05 to 80 ohms.Suspect it is the gauge,will look inside it after.

 

[Johnny]

Well thanks for posting John, now my gauge doesn't work. I have a similar problem. The wiring tests good. The sending unit is new and tested okay. I suspect the gauge since I didn't replace or have rebuilt. The two green battery leads connect to "B" post, the tank lead connects to "T" (I left the car + ground). If I lift the tank lead nothing happens, gauge still on empty, (with battery applied). If I ground the "T" post the needle jumps to 1/4 tank. I'll probably send to Nissonger for repairs.