Can you adjust sending units and gas gauge readings? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Zeke · 06-02-2007, 10:51 AM

with sender removed from tank use a multimeter set to ohms with one lead connected to sender wire and other to ground (metal part of sending unit) move the float and read meter. with full being 0 ohms it would seem your gage needle is off since you can't get any lower than zero=full. if you had something other than 0-90 the gage would never show full. I am not sure if the 0 ohms is the full reading since if you disconnect the sending wire, infinite ohms, it reads way past full

Rokcrln · 06-02-2007, 11:34 AM

I do have a digi meter and I am headed out now to pull the bed so in about an hour I will be back with info!

Kevin
LFD Inc.

jamis · 06-02-2007, 12:05 PM

Quote:

Originally Posted by Zeke

I am not sure if the 0 ohms is the full reading since if you disconnect the sending wire, infinite ohms, it reads way past full

0 ohms would be a perfectly closed circuit with no residence (sender wire completing the ground circuit threw the variable resister in this case). If you disconnect the wire it goes to empty, meaning an infinitely open circuit not the 0 ohms but its infinite opposite.

charlie diaz · 06-02-2007, 12:22 PM

Im not trying to sound like a smart-ass here, but if you said that the gauge reads 1/2 full when it is empty, then with the tank empty, cant you just pull the needle off the guage and press it back on at the empty line? Then it will read right at empty. It shouldn't really matter where the needle is at when you have a full tank, right? I mean the real intent of a fuel gauge is just to let you know when youre about to run out of gas.

Definitely keep us posted though. I'm about to undergo the same swap, and I was wondering what to do about the sending unit.

Rokcrln · 06-02-2007, 02:12 PM

Well it is my sending unit. The Ohm's reading was all over the place so I hooked it back up and manualy moved it thru it's range and it read fine unless you wiggled the unit at all then it would peg way past full or bounce off empty. In calling around for a new one (no luck, 4days out

) A guy told me they have had a problem that the cali gas tends to eat the contacts and causes eratic or no readings.

Kevin
LFD Inc.

06-02-2007, 10:51 AM	#1
Zeke Active Member Join Date: Jun 2002 Location: L.A. Lower Alabama Posts: 453	Re: Can you adjust sending units and gas gauge readings? with sender removed from tank use a multimeter set to ohms with one lead connected to sender wire and other to ground (metal part of sending unit) move the float and read meter. with full being 0 ohms it would seem your gage needle is off since you can't get any lower than zero=full. if you had something other than 0-90 the gage would never show full. I am not sure if the 0 ohms is the full reading since if you disconnect the sending wire, infinite ohms, it reads way past full __________________ 1969 C10 350 3spd 1995 GMC 3500 XC 350 dually When Thomas Edison worked late into the night on the electric light, he had to do it by gas lamp or candle. I'm sure it made the work seem that much more urgent. George Carlin

06-02-2007, 11:34 AM	#2
Rokcrln Senior Member Join Date: Jul 2005 Location: Winters Ca. 95694 Posts: 4,843	Re: Can you adjust sending units and gas gauge readings? I do have a digi meter and I am headed out now to pull the bed so in about an hour I will be back with info! Kevin LFD Inc.

06-02-2007, 12:22 PM	#4
charlie diaz Registered User Join Date: May 2005 Location: Colorado Posts: 138	Re: Can you adjust sending units and gas gauge readings? Im not trying to sound like a smart-ass here, but if you said that the gauge reads 1/2 full when it is empty, then with the tank empty, cant you just pull the needle off the guage and press it back on at the empty line? Then it will read right at empty. It shouldn't really matter where the needle is at when you have a full tank, right? I mean the real intent of a fuel gauge is just to let you know when youre about to run out of gas. Definitely keep us posted though. I'm about to undergo the same swap, and I was wondering what to do about the sending unit.

06-02-2007, 02:12 PM	#5
Rokcrln Senior Member Join Date: Jul 2005 Location: Winters Ca. 95694 Posts: 4,843	Re: Can you adjust sending units and gas gauge readings? Well it is my sending unit. The Ohm's reading was all over the place so I hooked it back up and manualy moved it thru it's range and it read fine unless you wiggled the unit at all then it would peg way past full or bounce off empty. In calling around for a new one (no luck, 4days out ) A guy told me they have had a problem that the cali gas tends to eat the contacts and causes eratic or no readings. Kevin LFD Inc.



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