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Old 03-10-2011, 08:44 PM   #1
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Help! Fuel sending unit ohms emtpy full

Would anyone know the correct aftermarket fuel gauge that would work in a 98 TJ, it has a 4cyl if it matters. I am putting a SBC in and would like to change to aftermarket gauges. Specifically i need to know what is the ohm reading full and empty. Thanks.
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Old 03-13-2011, 01:17 PM   #2
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With float in up position, resistance should be 20 ohms. With float in down position, resistance should be 220 ohm

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Old 03-13-2011, 09:03 PM   #3
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Quote:
Originally Posted by Pyro8541 View Post
With float in up position, resistance should be 20 ohms. With float in down position, resistance should be 220 ohm
Thanks, I think I will have to use a programmable fuel gauge. The closest I have been able to find is a 240/33.
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Old 03-13-2011, 09:34 PM   #4
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Just had a thought . I think a 20 ohm resistor in line might work. It would make the empty right on and the full would only be 7 ohms over. The empty is what I am most concerned about. Anyone have any thoughts on this?
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Old 03-14-2011, 08:57 PM   #5
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I just did a new complete guage cluster and the fuel was the biggest problem no one makes one for the TJ. I used custom Speedhut guages. The fuel is programable. Here is a link to them.
Kits Gauge, Speedhut Gauge Series by SpeedHut
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Old 03-14-2011, 09:11 PM   #6
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Quote:
Originally Posted by Ctflyer View Post
I just did a new complete guage cluster and the fuel was the biggest problem no one makes one for the TJ. I used custom Speedhut guages. The fuel is programable. Here is a link to them.
Kits Gauge, Speedhut Gauge Series by SpeedHut
Very cool...Speedo is programmable also. Thanks for the info.
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Old 03-14-2011, 09:27 PM   #7
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Here is what I went with.
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Old 03-14-2011, 10:21 PM   #8
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Nice! Did you make the cluster plate?
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Old 03-14-2011, 10:55 PM   #9
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Yes. I disassembled the old one and made a plate to fit all of the new gauges.
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Old 08-27-2013, 12:32 PM   #10
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it's an old thread i know but i was wondering if anyone knew what the resistance should be for a 93 wrangler fuel sending unit from empty to full. im trying to install aftermarket gauges but the one i bought isn't reading right. thanks again.
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Old 11-16-2015, 10:00 PM   #11
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I know these are old posts but I thought this would help a few people out, as I was in the dark myself and took the gamble.

The factory fuel sender uses a 270-20 ohm resistor. When I installed a fuel cell in my 2004 Rubicon, I used a 240-33 ohm sender from VDO available on Summits website (Summit part number VDO-226007) and my factory gauge is SPOT ON. Attach the hot wire to the post on the top of the sender and the signal wire to the "grounding" post and you'll be in business.

Many are saying you need a 20 ohm resistor according to "the math" for a correct empty reading. However, I believe they are under the impression that this is a 12 volt system. The fuel sender receives a 5 volt signal from the ECM. The 13 Ohm difference at empty is not enough to cause a significant change in the gauges reading. Proper positioning of the sender is critical take your time installing it.
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Old 12-06-2015, 05:20 PM   #12
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Just to revisit this. The fuel gauge was a little tricky as the factory gauge is a 240 full/ 33 empty sending unit. Use a 220/20 gauge and just put a 20 ohm resistor in line or use a rheostat with 20 ohm in its range(radio shack).

I used the rheostat and just adjusted for empty and put a dab of silicone to keep it there.

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