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ok , another electronics mental midget here... how can I test the fuel sending unit in the tank? can I jump it out? if there's one wire going to the gauge and the other is ground how does it get its power? is it governed by ground resistance? It's on a 72 mach 1...….

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Disconnect it from the wiring harness and using a meter it should read 73 ohms empty 10 ohms full. You cannot measure the ohms with it connected to the wiring. There is a specific setting on the meter to measure ohms. If you don't know how check the instructions or Youtube.

http://www.7173mustangs.com/gallery/1_01_07_15_8_53_18.png

 

"I love my Hookers!" and "Get some Strange" probably have a different connotation to non automotive enthusiasts!

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The positive side of the gauge connects to the instrument voltage regulator and the negative side connects to the sending unit and provides the variable ground reference at the resistance values Jeff mentioned.

 

 

“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein

 

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thanks guys!!

so I checked the resistance and all's good there, checking the constant voltage reg. the pos side was flashing???? is this normal? also looking at pictures of them on e=bay it looks like the one I have is for a 74-86..are they interchangeable? I also have a tack

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I believe they are interchangeable. Yes,they pulse. That is how they reduce the average voltage. There are solid state electronic ones available that provide a constant output. If you get one make sure it's adjustable.

 

 

“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein

 

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I believe they are interchangeable. Yes,they pulse. That is how they reduce the average voltage. There are solid state electronic ones available that provide a constant output. If you get one make sure it's adjustable.

so does it have to be adjusted when used? if so how

thanks, don

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Adjusting the voltage up or down allows you to fine tune the gauges, especially the fuel gauge. The stock ones have what looks like a little metal tab sticking out of the plastic, that can be turned to change the average voltage output, by adjusting the tension on the bi-metal spring in the unit.

 

 

“If you can't explain it simply, you don't understand it well enough.”

--Albert Einstein

 

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Fill the tank before adjusting so you can use the full mark as a basis for your adjustment

http://www.7173mustangs.com/gallery/1_01_07_15_8_53_18.png

 

"I love my Hookers!" and "Get some Strange" probably have a different connotation to non automotive enthusiasts!

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Fill the tank before adjusting so you can use the full mark as a basis for your adjustment

Actually, it is better to use a 1/4 tank of gas for adjusting the CVR output.  Think about it...isn't it better to know when you're about to run out of gas than it is to know when you're full?

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so if you have an existing installed tank with some gas in it, how do you get to a 1/4 tank to get a starting point?. . . I agree it is much easier to adjust the float with a 1/4 tank, and if you can get a exact 1/4 or 1/2 tank it will work too.

http://www.7173mustangs.com/gallery/1_01_07_15_8_53_18.png

 

"I love my Hookers!" and "Get some Strange" probably have a different connotation to non automotive enthusiasts!

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so if you have an existing installed tank with some gas in it, how do you get to a 1/4 tank to get a starting point?. . . I agree it is much easier to adjust the float with a 1/4 tank,  and if you can get a exact 1/4 or 1/2 tank it will work too.

 

 

Drain the tank, remove sender and calibrate to factory spec. Reinstall sender, pour in 5 gallons of gas and adjust your CVR.

 

 

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That's too much work calibrate it at full if you aren't replacing the sender. Refill at 1/2 tank. If it takes significantly more or less than 1/2 the tanks capacity, you'll know which way to adjust it.

http://www.7173mustangs.com/gallery/1_01_07_15_8_53_18.png

 

"I love my Hookers!" and "Get some Strange" probably have a different connotation to non automotive enthusiasts!

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