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Unread 05-09-2008, 01:27 PM   #1
boydog40
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new fuel sending unit calibration for CJ

I need instructions on how to calibrate a new fuel sending unit for my CJ-5
looked in the archives but found nothing
thanks

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Unread 05-09-2008, 08:26 PM   #2
NHwheelin
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I dont know if you can calibrate it. I installed a new unit in my cj7 and didnt even see anyway to calibrate it. I am pretty sure it is "plug and play"
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Unread 05-09-2008, 08:31 PM   #3
CrazyHorse6
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I agree- no calibration necessary unless you specifically purchased a sending unit for a different gal size tank than what you have.
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Unread 05-09-2008, 09:11 PM   #4
illinicj
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I didn't calibrate mine and it works fine. Although I suppose you could see how it works with your gauge in the high and low positions and bend the arm to get it where you want it. I doubt you'd need to.
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Unread 05-10-2008, 04:56 PM   #5
boydog40
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ok, well then maybe my gauge is bad because it reads full all the time when power is on
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Unread 05-10-2008, 05:24 PM   #6
mmerlina
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Are you sure the connections are right? If the gauge is moving freely and you can watch it go to "full" when the vehicle turns on, it sounds like it's not getting the correct signal.

http://www.jeeptech.com/electrical/gauges/

Take a look there.. about halfway down the page refers to the fuel gauge.. good luck.

If the resistance falls in this ballpark (depending on how much gas you have in the tank), then the sending unit is fine. If it shows infinitely HIGH resistance, then the sending unit could be bad OR the wire from the tank to the gauge could be open.
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1986 Jeep CJ7 (photos)
Remanufactured 258, ARB lockers front & rear, 4.10 Yukon gears, 35x12.5" Super Swamper SSR's, Motorcraft 2100, 4.5" Rubicon Express Extreme-Duty lift, York 210 OBA, Big Daddy steering, Tatton rear CV driveshaft, Herculined interior, TJ flares, lots of body & upholstery work
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Unread 05-10-2008, 06:44 PM   #7
JeepHammer
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Look up user John Strenk, he has a GREAT site on how to mess with CJ gauges!
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Unread 05-12-2008, 12:14 PM   #8
boydog40
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the only connections i disconnected were at the tank, which the gauge now is reading all over the place, never the same anytime I crank it - ground?
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Unread 05-12-2008, 02:58 PM   #9
mmerlina
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When I was doing my sending unit a local jeep mechanic told me to double check the ground because it's in a bad place and tends to rust over and give funny signals.. so yes it may be a ground..
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1986 Jeep CJ7 (photos)
Remanufactured 258, ARB lockers front & rear, 4.10 Yukon gears, 35x12.5" Super Swamper SSR's, Motorcraft 2100, 4.5" Rubicon Express Extreme-Duty lift, York 210 OBA, Big Daddy steering, Tatton rear CV driveshaft, Herculined interior, TJ flares, lots of body & upholstery work
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Unread 05-13-2008, 09:27 AM   #10
boydog40
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thanks will ck the ground, did you just clean your ground connection or run one straight from the battery back?
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Unread 05-13-2008, 10:03 AM   #11
CjinPA
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If it is reading full all of the time then it is going to ground. If it reads empty then you don't have a ground. If you want to check your gauge take the red wire with the plug on the end of it off of the sending unit, take a piece of wire as a jumper, and run it to a ground (frame). The gauge should go to full. Don't hold it directly to ground for too long or you risk ruining the fuel gauge.
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