1958 fuel gauge sprite

[sim]

Been working on fuel tank and sorting out a problem with fuel gauge. I had the gas tank off and replaced the sending unit gasket which was leaking. I also cleaned the connection to the sending unit. After reinstalling I checked the gauge to see what it would read with an empty tank. It was just to the right of the empty mark. I then added some fuel and it read 1/4 tank. Added more fuel and it did not move . I then filled the tank and it still read 1/4 tank. So I have been driving it to see what it would read when the tank got close to empty. after a short trip today the gauge does not respond. I pulled the connector under the hood and the gauge did not go to full. I am guessing the gauge died. any other thoughts?

Thanks

 

[Jim_Gruber]

Your Float if Plastic has become a "Sunk". Replace the Float with a Metal One. Also take a look a thread posted by Leecreek on ahexp.com under thread posed about meeting Trevor Jessie by SaxMan. I now understand why my new tank only reads 3/4 full. Read the note and see if it applies to you. But betting you've got a "Sunk".

 

[sim]

I will do that However float in metal and not sunk. This is still the original one that came with the car. I have had this car since 1973

 

[sim]

I cannot not find that post, Can you please past the URL here
Thanks

 

[Jim_Gruber]

Jim Here is what my brother and I found after the run to Lake of the Ozarks. The gas cap was a fight to r+r. My brother installed a new gas tank in the late 80's Cap never fit easily after that. Well we measured down the fill up pipe at his house on the way back and I do not remember the numbers but the length of the fill up was just too short to get a hand hold on the cap. When I was getting ready to paint the Sprite in 2008 I removed the tank to cut and extend the Fill up tube. I cut it off about 1-1.5 inches above the tank to put on a hose. Looked and measured the stub left in the tank and it was over 2" long inside the tank. Since the fuel tank is not vented but the cap is I slotted the extension inside the tank just below the welded top with a cut off wheel on the Dremel. Now I am getting a fuller tank. Before the gas gauge started dropping rather quickly. Now moer 'back to normal'. My brother said they must have made the tank on a Friday or Monday. Just my experience here. YMMV He calculated by the numbers and said it gets a little more than a gallon and a quarter in the tank as the tank quits filling once the level gets to the fill tube.

Attached Thumbnails

 

[dklawson]

From post#1:
I pulled the connector under the hood and the gauge did not go to full. I am guessing the gauge died. any other thoughts?

From post#3:
I will do that However float in metal and not sunk. This is still the original one that came with the car. I have had this car since 1973

Can you see the float in the tank??? Float arms can also get "stuck" from deposits and rust. However, your post saying you removed wires and the gauge didn't change suggests this is not a sender problem.

When you pulled the wire off the gauge, you were removing the green/black wire from the gauge's "T" terminal weren't you?

The magnetic gauges have to have a very good ground connection. Make sure your fuel gauge has a good ground by running an additional wire if necessary. If that does not fix it, visit the MGA Guru website and read through the gauge system and how to calibrate it. If you like gauges this can be interesting reading and fun to try.

MGA Guru Fuel Gauge Link

 

[smaceng]

Double down on everything that Doug said......good luck....if it turns out that you need a new sending unit, see if you can find someone who can rebuild it. New units seem to have a short life. Scott in CA

 

[sim]

no cannot see float but did check it when I had it out and it moved with out any problem.
The wire that I disconnected is under the hood on the right side. This should have made the gauge read full. I am going to test that connection with a test light to see if it has power. Next step is removing gauge.
thanks Rod

 

[sim]

Fuse broken had to use 5X glasses to see it .

 

[dklawson]

I'm glad you found the fuse problem. So the next question is "why did it blow"?

 

[sim]

most likly it is 25 years old. off to get another one Are these 30A?

 

[dklawson]

Careful with the fuse ratings. Lucas glass fuse ratings do not match the U.S. Bussman type fuse ratings. See the link below.
https://www.mgtoronto.com/pdf/Tech/fuses.pdf