Changing the resistance of a gas tank sender for aftermarket gauge?
Changing the resistance of a gas tank sender for aftermarket gauge?
(OP)
The stock sender sends a signal of 90 Ohm when empty, and 10 Ohm when full. The aftermarket gauge registers 73 Ohm Empty, and 8-12 Ohm full. The "Empty" measurement being accurate is more important to me.
Is there a way to add resistors in series (e.g. in-line with the signal wire going to the gauge) to change the value from 90 to 73 Ohm?
I suppose if there is not a way to make it work in series, I can also drop the gas tank and solder a wire from the sender to the signal wire. This will bypass the sender's variable resistor and I can put whatever resistor I need in the jumper wire.
73 is ~81% of 90.
8 is 80% of 10.
How do I decrease* resistance by 20%?
This is for a 12v automotive system.
Is there a way to add resistors in series (e.g. in-line with the signal wire going to the gauge) to change the value from 90 to 73 Ohm?
I suppose if there is not a way to make it work in series, I can also drop the gas tank and solder a wire from the sender to the signal wire. This will bypass the sender's variable resistor and I can put whatever resistor I need in the jumper wire.
73 is ~81% of 90.
8 is 80% of 10.
How do I decrease* resistance by 20%?
This is for a 12v automotive system.





RE: Changing the resistance of a gas tank sender for aftermarket gauge?
Otherwise you need an extra resistor in series, but that also strongly impacts on the full position.
If my memory of my high school physics still serves me 17 ohms in series will give you 90 and 27 ohms to the gauge in the empty and full positions.
Regards
Pat
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RE: Changing the resistance of a gas tank sender for aftermarket gauge?
There is another gauge that reads 90 Ohm FULL and 0 Ohm empty. I think I will just use that one, though I will probably get confused looks from my passengers when I tell them I need to stop for gas.
RE: Changing the resistance of a gas tank sender for aftermarket gauge?
TTFN
FAQ731-376: Eng-Tips.com Forum Policies
RE: Changing the resistance of a gas tank sender for aftermarket gauge?
h
Similar setups to the ATL in my Mini...sender just to the left of the filler neck....and the same type unit on the Al tank of my street roadster...one is adjustable but the other is not. They both read correctly with one Autometer and on VDO type fuel gauge!
Rod
RE: Changing the resistance of a gas tank sender for aftermarket gauge?
Rod
RE: Changing the resistance of a gas tank sender for aftermarket gauge?
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Changing the resistance of a gas tank sender for aftermarket gauge?
RE: Changing the resistance of a gas tank sender for aftermarket gauge?
Not sure why someone posts on a forum, waits 30 minutes and then gives up and goes ahead with something wrong....
People often only read a forum once per day so it could take 24hrs or more to get an answer.
RE: Changing the resistance of a gas tank sender for aftermarket gauge?
Rod
RE: Changing the resistance of a gas tank sender for aftermarket gauge?
still like that when I sold it!
RE: Changing the resistance of a gas tank sender for aftermarket gauge?
Then run till empty and then mark the position of the needle with an E on the face with a permanent marker.
Regards
Pat
See FAQ731-376: Eng-Tips.com Forum Policies for tips on use of eng-tips by professional engineers &
http://eng-tips.com/market.cfm
for site rules
RE: Changing the resistance of a gas tank sender for aftermarket gauge?
Finding/creating a 386ohm resistor and connecting it in parallel to the tank sensor is a simple task which makes the system work properly.
This appears to be just another 1-off hobby post anyways. We likely should have just red-flagged it.
RE: Changing the resistance of a gas tank sender for aftermarket gauge?
Also you are correct this certainly does not look like work related and the OP certainly does not seem like an engineer.
Regards
Pat
See FAQ731-376: Eng-Tips.com Forum Policies for tips on use of eng-tips by professional engineers &
http://eng-tips.com/market.cfm
for site rules
RE: Changing the resistance of a gas tank sender for aftermarket gauge?
I like your solution. Just as good as mine.
Bill
--------------------
"Why not the best?"
Jimmy Carter
RE: Changing the resistance of a gas tank sender for aftermarket gauge?
Regards
Pat
See FAQ731-376: Eng-Tips.com Forum Policies for tips on use of eng-tips by professional engineers &
http://eng-tips.com/market.cfm
for site rules
RE: Changing the resistance of a gas tank sender for aftermarket gauge?
Besides, with that gauge and sender combo the gauge will read empty with somewhere between 1/8 and 1/4 tank of fuel left so that fix doesn't work.
RE: Changing the resistance of a gas tank sender for aftermarket gauge?
RE: Changing the resistance of a gas tank sender for aftermarket gauge?
RE: Changing the resistance of a gas tank sender for aftermarket gauge?
Bill
--------------------
"Why not the best?"
Jimmy Carter