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  #11  
Old 07-09-2018, 07:18 PM
blue62tbird blue62tbird is offline
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So I got to the tank access from the trunk. There is one wire coming out of tank. First of all I used my circuit tester for a ground wire. If I grounded the wire coming to the tank, the gauge would only go to 3/4 and the test light blinked, I assume that the circuit is good then? It was not till later when after I put everything back together that a little further up the harness wire to tank the wire to the tank had TWO inside of it. Anyway, where the wire from gauge to wire from tank connect, if I left a little of the metal male plug stick out that was connected to the female plug and clip my test to that metal pc and grounded it the gauge went to full.
When I filled it last I have put about 40 miles on the car. Assuming I pull 10 MPG could it still be reading full? Note if I bounced the rear end up and down the gauge did not budge as I thought it would as many old car gauges do from back in the day.
So I put it all back together. I scrapped off a part of the lip on the tank and ran a ground (my test light) to the car (several diff places), gauge just stayed at 1/4 full as it always is since I got it.
So I don't know, seems to me I have a bad sending unit?
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  #12  
Old 07-09-2018, 07:44 PM
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You have a 20 gallon tank. At 10 mpg you only used 4 gallons so it should read above 3/4. If you ground the wire to the sender and the gauge goes up then the circuit is good. Since you grounded the sender to the body of the car and it didn't change the problem is with the sender.

John
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  #13  
Old 07-09-2018, 08:05 PM
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ok I am confused or I confused you. Your reply confused me.
When I disconnect the wire from sending unit in tank from the wire coming from the gauge (which appears to have two wires in it??)
If I ground that wire end female plug from gauge, the gauge reads to 3/4.
If I plug the wire from tank into the wire from gauge leaving a little metal exposed yet both connections are connected and I ground it, the tank goes to full line every time I do it.
If I plug it all together and try to ground tank it just stays at 1/4 as always.
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  #14  
Old 07-09-2018, 08:19 PM
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You have the wire connected to the sender and you ground the sender to the body of the car and the gauge stays at 1/4. That proves that the ground to the tank is not the issue. You remove the wire from the sender and you ground it and the gauge goes up. That proves that the gauge is working. Why the gauge only goes to the 3/4 mark when you ground the end of the wire and the full mark when you ground the connector in the harness is odd. You can run a new piece of wire and see if it changes. Regardless the main problem is with the sender.

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  #15  
Old 07-09-2018, 08:33 PM
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you say sending meaning sending unit in tank. If I pull that wire out of wire from gauge, and ground the wire from said tank, why would it do anything, what does it have to send, it has no power to it. Sorry been a hot day at work. This is going over my head.
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  #16  
Old 07-09-2018, 08:35 PM
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If you haven't already done it remove the pig tail wire that goes from the sender to the harness and run a new wire to the sender. You can use alligator clips temporarily. You could have an internal break in that small wire. It could be just enough to affect the reading. The fact that you say it works every once in a while could be a clue that it's a bad wire.

John
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  #17  
Old 07-09-2018, 08:41 PM
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The wire going into the tank (the sender) goes into some type of rubber seal at the tank, do I just pull it out gently or opening up the tank to get to the the wire?
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  #18  
Old 07-09-2018, 08:48 PM
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You said the wire from the sender goes into a connector (most likely a bullet connector). If you ground the wire at that point the gauge goes to full. Remove the wire at the bullet connector and run a new wire temporarily from there to the sender. See if the gauge goes above 1/4.

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  #19  
Old 07-09-2018, 08:48 PM
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I don't get when I connect the sender to the harness, leaving juuust enough metal exposed and I ground the two connect wires it goes to a full tank.
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  #20  
Old 07-09-2018, 08:53 PM
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If you ground any part of the wire from the sender back to the gauge it's going to read full. Once you ground it you take the sender out of the circuit.

John
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