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PostPosted: April 12, 2018, 1:10 am 
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Joined: February 12, 2008, 2:08 am
Posts: 296
Location: Olympia WA
Hello group,
I am hoping for a simple fix, maybe you can help. I just swapped out the few tank in my car. The new tank came with its own fuel sender. Now the gauge reads at 1/2 when it is full. The gauge operates from 240-33 ohm range. Can I add a resistor to get it to read correctly? If so, what size resistor?
Thanks JEB

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PostPosted: April 12, 2018, 8:47 am 
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Joined: July 17, 2008, 9:11 am
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Location: West Chicago,IL
JEB, unfortunately, no. You can do add a resistor to make it read correct at one level but it won't read correct over the full range. You are left with replacing the sending unit to match the gauge, replacing the gauge with one that matched the sender, buying a converter ( $80-125), or simply making a mental note of the calibration.

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PostPosted: April 12, 2018, 9:34 am 
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Joined: April 23, 2006, 8:26 pm
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Unfortunately, no; there are probably about a dozen "standard" values when it comes to fuel sensors. Probably the cheapest solution is to get another sender or gauge to match. Well, the cheapest solution is to just mentally multiply or divide the gauge reading to know what it really is, if you don't mind.

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Last edited by KB58 on April 12, 2018, 3:04 pm, edited 1 time in total.

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PostPosted: April 12, 2018, 2:26 pm 
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Joined: November 13, 2009, 9:31 pm
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Location: Connecticut
Maybe...

You might be able to do a series/parallel set of resistors to get the end points to at least coincide.
The gage wants 240 full and 33 empty?
What is the range on the new sender?

(edit) I took a quick look, and Chuck's right, there isn't a simple method to add resistors, even the series/parallel can only get one end of the range corrected.

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Last edited by duratec7 on April 13, 2018, 1:00 pm, edited 1 time in total.

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PostPosted: April 12, 2018, 7:29 pm 
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Joined: February 15, 2018, 8:32 pm
Posts: 42
Location: Vancouver, BC. Canada
DC Voltage Doubler Circuit:

https://www.electronics-tutorials.ws/bl ... rcuit.html

Simple circuit:

http://www.instructables.com/id/DC-DC-v ... e-circuit/


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PostPosted: April 12, 2018, 8:01 pm 
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Joined: February 15, 2018, 8:32 pm
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Location: Vancouver, BC. Canada
For a $-buck, this looks like it has potential:

https://www.aliexpress.com/item/MT3608- ... lsrc=aw.ds


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PostPosted: April 12, 2018, 8:29 pm 
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Trog the problem with your proposal is that the traditional fuel gauge works on a current bridge using the matched parameters between the windings in the meter and the resitance of the sender, not applied voltage or simple resistance divider. I suppose a circuit could be designed using a JFET. but that is not a simple task for someone not schooled in electronics.

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PostPosted: April 13, 2018, 1:10 am 
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Joined: February 12, 2008, 2:08 am
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Location: Olympia WA
Thanks guys,
Your thoughtful feed back is appreciated. And, Chuck, thanks for explaining how it works. The 89 cent DC things looks interesting too.

I think I can look at how close to E that I am and go from there.

All the best
JEB

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● I have a dream: My car has a new type of engine: a half-turbine half-reciprocated engine. I invented it! ~ Dr. Felix Wankel
● It has occurred to me, amateurs built the ark and professionals built the titanic.


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PostPosted: April 13, 2018, 1:31 am 
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rx7locost wrote:
Trog the problem with your proposal is that the traditional fuel gauge works on a current bridge using the matched parameters between the windings in the meter and the resitance of the sender, not applied voltage or simple resistance divider. I suppose a circuit could be designed using a JFET. but that is not a simple task for someone not schooled in electronics.



Interesting...I wonder if a simple change in the gauge scaling resister would solve the range issue?


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PostPosted: July 2, 2018, 5:07 pm 
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Joined: August 8, 2014, 6:08 pm
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Location: Green Bay, WI
I’ve had problems with my fuel gage also, and it’s fully programmable. It will work with about 8 different senders. I honestly don’t get it.

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PostPosted: July 2, 2018, 5:21 pm 
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Steve, tell us your gauge make and model (so I can look up the instructions), and the sensor empty and full resistances. Some gauges that I have seen will even allow a custom sender program. Maybe I can help.

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