Fuel Gage Ohms - The 1947 - Present Chevrolet & GMC Truck Message Board Network

70GMCer · 01-02-2009, 01:06 PM

What should the fuel gage read in Ohms by itself? In other words, what would the Ohm reading be with the gage out of the dash, without any wires connected to it?

skidder111 · 01-02-2009, 01:28 PM

My understanding is that the gauge itself shouldn't read anything; it is a kind of ohmmeter in its own. It reads the resistance created by the sending unit. The sending unit ranges 0-100 ohms (depending on fuel level) so the gauge operates in that range.

70GMCer · 01-02-2009, 01:36 PM

Shouldn't there be a standard reading of resistance at the connections between the coil on the back of the gage?

longhorn_SD69 · 01-02-2009, 01:41 PM

your fuel guage will more than likely read some where between 0.01 ohms to .10 ohms the needle just move depends on how much voltage is applied to by the fuel sending unit. the resistance reading on that is dependent on the number of windings on it the only way you'll really be able to tell is to buy a new fuel sending unit and compare its readings to the one you have unless you have a reference manual on them.

also to answer the other question the resistance reading on the coil on the back of the guage is dependant on the number of coils on your guage. that coil just acts as a capacitor. in other words it requires a certain voltage from your fuel sending unit to show you the various levels of fuel that you have.

skidder111 · 01-02-2009, 01:51 PM

According to the factory assembly manual the resistance from the sending unit is 0 - 100 ohms.

70GMCer · 01-02-2009, 02:01 PM

So, there is really no way to tell if the gage is working or not out of the truck. I am going to sell it and would have been nice to say it Ohms out good. Oh well, I'll just sell it as is. Thanks for your help on this.....

longhorn_SD69 · 01-02-2009, 02:04 PM

well there is a way if your fuel guage read a larg number of ohms it has an open and will not work there should be a little resistance on it but not much. take a reading and let me know what it is i'll confirm it for you.

70GMCer · 01-02-2009, 02:31 PM

045.8 reading......

longhorn_SD69 · 01-02-2009, 02:51 PM

there should not be a problem with it then. hook'r up.

70GMCer · 01-02-2009, 03:08 PM

Thanks again....

c10crazy · 01-02-2009, 05:05 PM

Here ya go in post #6
http://67-72chevytrucks.com/vboard/s...gauge+readings

longhorn_SD69 · 01-02-2009, 05:16 PM

so there's a 5 ohms diference that could be accounted for by the manufactured of the guage but it should work still thanks for that link!

70GMCer · 01-02-2009, 05:19 PM

Thank you....

01-02-2009, 01:06 PM	#1
70GMCer Senior Member Join Date: Apr 2005 Location: Joppa, Maryland Posts: 4,408	Fuel Gage Ohms What should the fuel gage read in Ohms by itself? In other words, what would the Ohm reading be with the gage out of the dash, without any wires connected to it? __________________ 1997 GMC Sierra Ext 1965 Mustang

01-02-2009, 01:28 PM	#2
skidder111 Registered User Join Date: Jan 2008 Location: Pincher Creek, Alberta, Canada Posts: 140	Re: Fuel Gage Ohms My understanding is that the gauge itself shouldn't read anything; it is a kind of ohmmeter in its own. It reads the resistance created by the sending unit. The sending unit ranges 0-100 ohms (depending on fuel level) so the gauge operates in that range.

01-02-2009, 01:36 PM	#3
70GMCer Senior Member Join Date: Apr 2005 Location: Joppa, Maryland Posts: 4,408	Re: Fuel Gage Ohms Shouldn't there be a standard reading of resistance at the connections between the coil on the back of the gage? __________________ 1997 GMC Sierra Ext 1965 Mustang

01-02-2009, 01:41 PM	#4
longhorn_SD69 Registered User Join Date: Dec 2008 Location: smithfield, va Posts: 29	Re: Fuel Gage Ohms your fuel guage will more than likely read some where between 0.01 ohms to .10 ohms the needle just move depends on how much voltage is applied to by the fuel sending unit. the resistance reading on that is dependent on the number of windings on it the only way you'll really be able to tell is to buy a new fuel sending unit and compare its readings to the one you have unless you have a reference manual on them. also to answer the other question the resistance reading on the coil on the back of the guage is dependant on the number of coils on your guage. that coil just acts as a capacitor. in other words it requires a certain voltage from your fuel sending unit to show you the various levels of fuel that you have. __________________ Good Wood Last edited by longhorn_SD69; 01-02-2009 at 01:44 PM.

01-02-2009, 01:51 PM	#5
skidder111 Registered User Join Date: Jan 2008 Location: Pincher Creek, Alberta, Canada Posts: 140	Re: Fuel Gage Ohms According to the factory assembly manual the resistance from the sending unit is 0 - 100 ohms.

01-02-2009, 02:01 PM	#6
70GMCer Senior Member Join Date: Apr 2005 Location: Joppa, Maryland Posts: 4,408	Re: Fuel Gage Ohms So, there is really no way to tell if the gage is working or not out of the truck. I am going to sell it and would have been nice to say it Ohms out good. Oh well, I'll just sell it as is. Thanks for your help on this..... __________________ 1997 GMC Sierra Ext 1965 Mustang

01-02-2009, 02:04 PM	#7
longhorn_SD69 Registered User Join Date: Dec 2008 Location: smithfield, va Posts: 29	Re: Fuel Gage Ohms well there is a way if your fuel guage read a larg number of ohms it has an open and will not work there should be a little resistance on it but not much. take a reading and let me know what it is i'll confirm it for you. __________________ Good Wood

01-02-2009, 02:31 PM	#8
70GMCer Senior Member Join Date: Apr 2005 Location: Joppa, Maryland Posts: 4,408	Re: Fuel Gage Ohms 045.8 reading...... __________________ 1997 GMC Sierra Ext 1965 Mustang

01-02-2009, 02:51 PM	#9
longhorn_SD69 Registered User Join Date: Dec 2008 Location: smithfield, va Posts: 29	Re: Fuel Gage Ohms there should not be a problem with it then. hook'r up. __________________ Good Wood

01-02-2009, 03:08 PM	#10
70GMCer Senior Member Join Date: Apr 2005 Location: Joppa, Maryland Posts: 4,408	Re: Fuel Gage Ohms Thanks again.... __________________ 1997 GMC Sierra Ext 1965 Mustang

01-02-2009, 05:05 PM	#11
c10crazy Like a Rock! Join Date: May 2002 Location: USA Posts: 1,092	Re: Fuel Gage Ohms Here ya go in post #6 http://67-72chevytrucks.com/vboard/s...gauge+readings __________________ 69 LWB Runs great - work in progress Mess with me and you mess with the whole trailer park!

01-02-2009, 05:16 PM	#12
longhorn_SD69 Registered User Join Date: Dec 2008 Location: smithfield, va Posts: 29	Re: Fuel Gage Ohms so there's a 5 ohms diference that could be accounted for by the manufactured of the guage but it should work still thanks for that link! __________________ Good Wood

01-02-2009, 05:19 PM	#13
70GMCer Senior Member Join Date: Apr 2005 Location: Joppa, Maryland Posts: 4,408	Re: Fuel Gage Ohms Thank you.... __________________ 1997 GMC Sierra Ext 1965 Mustang



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