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Hello all, first off i did a search of the site and could not find the answer to my question. So , i have installed a new auto meter fuel gauge 0-90ohm in my 66. I just installed a new fuel sending unit(orginal style). The tank is near empty with fuel,but the gauge is reading past the full mark. I have checked and rechecked the ground. There is a new ground wire on the sender that i have mounted to the frame. I pulled the ground wire and it still reads full. Any help on this is appreciated. Thanks.

Len
 

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Hello all, first off i did a search of the site and could not find the answer to my question. So , i have installed a new auto meter fuel gauge 0-90ohm in my 66. I just installed a new fuel sending unit(orginal style). The tank is near empty with fuel,but the gauge is reading past the full mark. I have checked and rechecked the ground. There is a new ground wire on the sender that i have mounted to the frame. I pulled the ground wire and it still reads full. Any help on this is appreciated. Thanks.

Len
Put and Ohm meter on the wire going to the fuel gauge. It should be around 5 - 15 ohms if the gas level is where you say it is. The guage is just an ohm meter with a dial.
 

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Hello all, first off i did a search of the site and could not find the answer to my question. So , i have installed a new auto meter fuel gauge 0-90ohm in my 66. I just installed a new fuel sending unit(orginal style). The tank is near empty with fuel,but the gauge is reading past the full mark. I have checked and rechecked the ground. There is a new ground wire on the sender that i have mounted to the frame. I pulled the ground wire and it still reads full. Any help on this is appreciated. Thanks.

Len
Ok, you have installed a new gauge AND a new sending unit.

Like any troubleshooting, you need to work from one end of the system to the other whether it be from the gauge end or the sending unit end.

Somewhere they is a problem or problems that need to be corrected.

I would begin with a spot you can begin troubleshooting. With all of the troubles I've seen with fuel level/gauge systems I would start at the connector that plugs into the sending unit in the gas tank. With it disconnected and the ignition switch in the on position the gauge should read full or above. If it does then you need to do another test by grounding this wire going TOWARDS the gauge to a good chassis ground. With it grounded the gauge should then read empty or below this on the gauge. If both of these tests have the gauge moving and reading like I've said then the problem is probably from this connection on the tank, through the sending unit to a ground and the gauge is good.

If the gauge does not read full scale with having the sending unit wire disconnected and grounded then a problem is from that point forward towards the gauge.

Since I do not know what your test results are, let's say with the sending unit disconnected off of the sending unit the gauge reads full or above and then when grounded it goes to empty or below. I would then have to think then that the gauge is working properly. I would then think that there is a problem with the sender and it's related wiring. Just because things are new does not mean they work properly. Chances are I would also do a test with some resistors inline on the wire going forward towards the gauge and is it would have a 45 ohm resistor inline between the sending unit wire towards the gauge and ground the gauge would read 1/2 full. If this resistor was changed out with a 22.5 ohm then the gauge would read 1/4 tank and then for a final check with a 67.5 ohm resistor the gauge should read 3/4 full. Just trying to show how things work, you have a 0-90 ohm fuel level gauge so if you split the difference with a 45 ohm resistor (which this is what a fuel sender is but variable due to it reads different or varying levels of fuel in the tank) then the gauge should read in the middle.

Now let's say with the test's the gauge does not move with it's sending unit wire grounded or ungrounded back by the tank. I would then be looking to see if the gauge has the proper voltage going to it, a proper ground, and an unbroken connection on the wire back to the gas tank.

Jim
 
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