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Old 03-03-2011, 05:43 PM
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Fuel level gauge ohms reading

I have a 0-30 ohm sender and got a 1318 autometer gauge from summit some time ago. This was after trying to use my stock 31 chevy gauge with a voltage reucer for 12 volts. That gauge only read a little above 1/2 tank when full.
The new autometer read the same so I just lived with it. It did deflect to empty as fuel was used.
i have now decided to get to the bottom of this and metered the sender and read 7 ohms with 1/3 tank.
Metered the gauge which is supposed to be 0-30 ohms and it reads 93 ohms.
I am assuming it was labeled wrong and ordering another will fix my problem.
What do you think?
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Old 03-03-2011, 09:01 PM
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hi,
hook the gauge up as to be able to read it and access the connections on it...connect ignition and ground, attach a wire to the sender terminal. power up gauge.
from radio shack, acquire 100 ohm 1/2 watt resistors, four would be good but two will work in also. take one resistor connect one end to sender lead, touch other lead to ground. note gauge reading, will probably be full tank. add additional resistors in parallel one at a time. two in parallel will be around 50 ohms..which should register around 1/2 on 90 ohm gauge, still full on 30 ohm.
three in parallel will be around 33 ohms..1/3 tank on 90 ohm, still full, maybe slight deflection on 30 ohm.
hope this helps.
mark
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Old 03-04-2011, 02:51 PM
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The Autometer 1318 gauge requires a sender that is 0 ohms at empty and 30 ohms at full.
So when the gauge reads empty it is receiving full 12 volts. When the gauge reads full the voltage is reduced by adding the resistance (30 ohms) to the circuit.
It doesn't make sense the when adding 90 ohms to the circuit the gauge reads 1/2 full. Something is back**swards.
When the gauge is disconnected from the wiring observe the position of the needle. Then connect the gauge to a 12 volt source and observe the needle. It should be on E. Then connect a resistance of 30 ohms in series with one of the wires going to the gauge. The gauge should read full.
If that doesn't work try other resistances to see what the correct range is.

vicrod
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Old 03-04-2011, 05:18 PM
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Giot resistors today and will work on it tomorrow.
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Old 03-04-2011, 05:19 PM
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Quote:
Originally Posted by ween
hi,
hook the gauge up as to be able to read it and access the connections on it...connect ignition and ground, attach a wire to the sender terminal. power up gauge.
from radio shack, acquire 100 ohm 1/2 watt resistors, four would be good but two will work in also. take one resistor connect one end to sender lead, touch other lead to ground. note gauge reading, will probably be full tank. add additional resistors in parallel one at a time. two in parallel will be around 50 ohms..which should register around 1/2 on 90 ohm gauge, still full on 30 ohm.
three in parallel will be around 33 ohms..1/3 tank on 90 ohm, still full, maybe slight deflection on 30 ohm.
hope this helps.
mark
never mind

Last edited by latech; 03-04-2011 at 05:35 PM.
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Old 03-04-2011, 05:26 PM
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the gauge may be defective .
This here may help.
http://mgaguru.com/mgtech/electric/fg_05.htm
I think there are only 2 fields in my 64 fuel gauge.
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Old 03-04-2011, 05:35 PM
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Quote:
Originally Posted by latech
the gauge may be defective .
This here may help.
http://mgaguru.com/mgtech/electric/fg_05.htm
I think there are only 2 fields in my 64 fuel gauge.
Thanx latech. Great info at that site.
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Old 03-04-2011, 05:36 PM
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Yeah I kind need pictures to help.
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Old 03-04-2011, 06:34 PM
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Hey...just remembered something else. My gauge had a little extra grease on the armature where it sets in the bushing that lets it swivel. I figured out that it helps to slow the needle movement down,I think this is to help keep it from jumping around so radically when the fuel sloshes in the tank. Thought you might like to know.Kind of a dampening effect.
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Old 03-04-2011, 06:47 PM
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It was a light grease , you dont want a grease that gets real thick when cold, it would cause the gauge to stay put, a soft grease like white grease that doesnt dry out.I am having a problem remembering the exact grease I used. You get the Idea though
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