Need help testing 69 fuel gauge / sending unit
Thread Starter
Racer
Joined: May 2005
Posts: 399
Likes: 4
From: Suffield CT
Need help testing 69 fuel gauge / sending unit
Hi, i tried watching willcox vid and then perform the tests, not sure where to go from here.
My fuel gauge reads at 3 o'clock when i start the car, and sometimes reads correct while driving, those are the symptoms. Currently tank is full of gas.
Willcox instructions said:
Next ground the ohm wire and the gauge should read empty "E".
With the key ON mine does but want someone to look at pic to verify i "grounded" the
wire properly.
https://photos.app.goo.gl/7nwGF4dh38DVWyZFA
Willcox instructions said:
with the Ohm wire removed and the key ON the gauge should read past full and horizontal, like 3 o'clock.
Mine does that too.
BTW i had the ground terminal for the sending unit plugged in, was that correct ?
If these 2 tests were performed correctly, i think it means gauge in dash is fine, and the ohm wire from tank to gauge in car is fine.
So now i am stumped why the gauge likes to read 3 o'clock 90% of the time ?
thanks for any help.
-ALF out...
My fuel gauge reads at 3 o'clock when i start the car, and sometimes reads correct while driving, those are the symptoms. Currently tank is full of gas.
Willcox instructions said:
Next ground the ohm wire and the gauge should read empty "E".
With the key ON mine does but want someone to look at pic to verify i "grounded" the
wire properly.
https://photos.app.goo.gl/7nwGF4dh38DVWyZFA
Willcox instructions said:
with the Ohm wire removed and the key ON the gauge should read past full and horizontal, like 3 o'clock.
Mine does that too.
BTW i had the ground terminal for the sending unit plugged in, was that correct ?
If these 2 tests were performed correctly, i think it means gauge in dash is fine, and the ohm wire from tank to gauge in car is fine.
So now i am stumped why the gauge likes to read 3 o'clock 90% of the time ?
thanks for any help.
-ALF out...
Last edited by fazang; Jun 26, 2020 at 10:57 AM.
Thread Starter
Racer
Joined: May 2005
Posts: 399
Likes: 4
From: Suffield CT
I finally found this and i think i have a bad sending unit like you said.
my multimeter reads 1. when i put terminals on sending unit ohm connector and ground.
http://repairs.willcoxcorvette.com/w...it-testing.pdf
thanks.
my multimeter reads 1. when i put terminals on sending unit ohm connector and ground.
http://repairs.willcoxcorvette.com/w...it-testing.pdf
thanks.
Race Director
Joined: May 2006
Posts: 18,740
Likes: 2,583
You did the test with a full tank of gas. Do the test with 1/2 tank and see if you get same results to confirm bad sender.
When you have 1/2 tank, turn on instrument lights, place key in run position, open tank and reach in and pull float up while watching gauge to see if it moves.
When you have 1/2 tank, turn on instrument lights, place key in run position, open tank and reach in and pull float up while watching gauge to see if it moves.
Thread Starter
Racer
Joined: May 2005
Posts: 399
Likes: 4
From: Suffield CT
I just buttoned everything back up, so will wait til 1/2 tank, thanks.
trying to get rear high enough so can do this test, but my jack and a 2X4 may not be tall enough to get master cylinder level... :-(
trying to get rear high enough so can do this test, but my jack and a 2X4 may not be tall enough to get master cylinder level... :-(
Team Owner
Joined: Jul 2004
Posts: 40,412
Likes: 792
From: Redondo Beach, California
Take off the gas cap, stick your hand down into the fuel tank, grab the gasoline float and pull it up. The gas gauge should read full. Push the float all the way down, the gas gauge should read emply. The "sender" is basically a wire wound reostat with the resistance reading determined by the float position. As you move the float up and down, the gas gauge should move up and down smoothly. Have someone siti the car to watch the gas gauge move.
The fuel tank will have gasoline and air in it, no smoking!
The fuel tank will have gasoline and air in it, no smoking!
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