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Fuel gauge went out?


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I went for a drive the other day and saw that my gauge was as empty as I've ever seen it. Naturally, I figured I was just out of gas (as usual) and went to fill it up. After doing so I realized that the gauge hadn't moved at all so I went ahead with some tests.

 

I checked the connection at the plug to the sending unit...good.

 

I checked the fuse that the circuit is on...good. Also tested for power on both sides of the fuse...good.

 

I checked the gauge to see if it worked by jumpering the power feed to the gauges at the plug to one terminal and grounding the other side. The gauge itself functions properly.

 

So I'm pretty lost on what it could be. I infer that there could be a break in connection somewhere before the instrument panel plug. Does anyone have a legible schematic for this circuit? Does anybody know what could be the issue?

 

Thanks guys!

 

Sent from my SM-G900V using Tapatalk

If you don't have time to do it right the first time, you sure as Hell don't have time to do it right the second time.

 

Dutch uncle

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Could be that you have a hole in the sending unit float and it filled with gas which would then always indicate an empty tank. If you have an ohm meter take a resistance reading between the 2 studs on the gas tank sensor. It should read between 10 and 72 ohms. If the tank is empty you should see 72 ohms and if full 10 ohms or a reading between those two depending on how full the tank is. Also at the plug for the float with the key in the run position you should see 5V at the plug at one of the terminals and gnd at the other.

-john

(jbojo)

351C 4V cc heads, 10.5 : 1 CR, 290 Herbert cam, Flat top forged pistons, forged connecting rods, Atomic efi,

C6 with Gear Vendor overdrive, 3.89 Tru Trac, Hooker Super Comp with 2 1/2" Pypes Exhaust.        

 

Some Mod pictures can be seen at: [button=http://www.7173mustangs.com/forum-garage?filterxt_uid=2026]Bojo's Garage[/button]

 

 

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I forgot to mention that I tested for power at the plug with the ignition on and it didn't show any power there. Interesting about the float, I'll check that.

 

Sent from my SM-G900V using Tapatalk

If you don't have time to do it right the first time, you sure as Hell don't have time to do it right the second time.

 

Dutch uncle

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I forgot to mention that I tested for power at the plug with the ignition on and it didn't show any power there. Interesting about the float, I'll check that.

 

Sent from my SM-G900V using Tapatalk

 

Also if you jumper the fuel tank plug connections the fuel gauge should indicate full at key on.

-john

(jbojo)

351C 4V cc heads, 10.5 : 1 CR, 290 Herbert cam, Flat top forged pistons, forged connecting rods, Atomic efi,

C6 with Gear Vendor overdrive, 3.89 Tru Trac, Hooker Super Comp with 2 1/2" Pypes Exhaust.        

 

Some Mod pictures can be seen at: [button=http://www.7173mustangs.com/forum-garage?filterxt_uid=2026]Bojo's Garage[/button]

 

 

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Thanks all, turned out to be a wire I hooked up for my voltmeter was tapped off the accessory wire from the ignition to the cluster. I hooked it a week or so ago.. oops, didn't notice it was drawing all the power off of the circuit. Cut the wire, and bang! Gas gauge working again.

If you don't have time to do it right the first time, you sure as Hell don't have time to do it right the second time.

 

Dutch uncle

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