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#1 |
Registered User
Join Date: Oct 2013
Location: Shelbyville, IL
Posts: 111
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Gas gauge issue
My 64 gas gauge reads 1/2 full when it is full, but once it gets to 1/2 it reads accurate down to empty. I took the sending unit out and it reads the same when I move it manually. When I ground the sending unit wire it goes to E. When is is just disconnected it goes to F so the gauge itself seems to be OK. I'm assuming the sending unit is defective, but strange that it reads only to 1/2. Any ideas on what is going on? Thanks.
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1948 Chevy 1/2T 1964 Chevy 1/2T stepside short bed 1939 Pontiac coupe Street Rod 2005 GMC 1/2T short bed |
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#2 |
State of Confusion!
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Location: Gulfport, MS USA
Posts: 46,929
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Re: Gas gauge issue
Measure the resistance of the sending unit in the various positions. I believe to register full it should be around 90 ohms out of the sending unit and zero for empty.
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Bill 1970 Chevy Custom/10 LWB Fleetside 2010 Toyota Tacoma PreRunner SR5 Double Cab - DD Member of Louisiana Classic Truck Club (LCTC) Bill's Gallery Life isn't tied with a bow, but it's still a gift. Live simply. Love generously. Care deeply. Speak kindly. Leave the rest to God! Last edited by Palf70Step; 12-04-2015 at 10:36 PM. |
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#3 |
Never Ending Projects
Join Date: Jul 2006
Location: San Diego, CA
Posts: 3,836
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Re: Gas gauge issue
If I remember correct, '64 should be 0-30 ohms. I think '66 was the first year with 0-90 ohms but I am sure I'll get corrected on that. LOL
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. 1965 C10 Panel, ![]() 1968 Chevy C10, Long, Fleetside, Hot Rod Hauler http://67-72chevytrucks.com/vboard/s...d.php?t=313233 SOLD 1965 Chevy C10, Long, Fleetside, Hot Rod C10 http://67-72chevytrucks.com/vboard/s...d.php?t=415702 SOLD We were given two ears and one mouth for a reason... listen twice as much and speak half as often... |
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#4 |
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Join Date: Sep 2012
Location: oceanside CA
Posts: 706
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Re: Gas gauge issue
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#5 | ||
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Join Date: Nov 2009
Location: Sherman, ME
Posts: 2,359
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Re: Gas gauge issue
Quote:
![]() So when measuring a sending unit in one of these '60 - '66 trucks, it should be close to 30Ω in the full position and close to zero empty. Quote:
However, there is one situation where the gauge can still pass that test but still not read correctly. That happens when the resistor on the back of the gauge fails (or isn't making a good connection). On the newer 0 - 90Ω gauges, a failed resistor will prevent the gauge from reading much over 1/4 tank. I have never dealt with one of these older 0 - 30Ω gauges with a failed resistor to know exactly how high they'll read in that situation. But it would be worth checking before you replace the sending unit. |
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#6 | |
State of Confusion!
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Location: Gulfport, MS USA
Posts: 46,929
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Re: Gas gauge issue
Quote:
Good to know. I either didn't remember the resistance change or never knew it. Glad to have gained some new info, especially the gauge resistor part..
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Bill 1970 Chevy Custom/10 LWB Fleetside 2010 Toyota Tacoma PreRunner SR5 Double Cab - DD Member of Louisiana Classic Truck Club (LCTC) Bill's Gallery Life isn't tied with a bow, but it's still a gift. Live simply. Love generously. Care deeply. Speak kindly. Leave the rest to God! |
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#7 |
Registered User
Join Date: Oct 2013
Location: Shelbyville, IL
Posts: 111
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Re: Gas gauge issue
I just put the ohm meter on the sending unit. It reads just shy of 30 ohm at empty and 25 ohm full?
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1948 Chevy 1/2T 1964 Chevy 1/2T stepside short bed 1939 Pontiac coupe Street Rod 2005 GMC 1/2T short bed |
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#8 |
Never Ending Projects
Join Date: Jul 2006
Location: San Diego, CA
Posts: 3,836
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Re: Gas gauge issue
Bad sender then.
__________________
. 1965 C10 Panel, ![]() 1968 Chevy C10, Long, Fleetside, Hot Rod Hauler http://67-72chevytrucks.com/vboard/s...d.php?t=313233 SOLD 1965 Chevy C10, Long, Fleetside, Hot Rod C10 http://67-72chevytrucks.com/vboard/s...d.php?t=415702 SOLD We were given two ears and one mouth for a reason... listen twice as much and speak half as often... |
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#9 |
Registered User
Join Date: Oct 2013
Location: Shelbyville, IL
Posts: 111
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Re: Gas gauge issue
Thanks. I took it apart and everything looks OK. I bent the point contact out so it would make better contact with the windings, but no difference. I guess the small windings must wear out or break after 50 years of use. Guess it's time to buy my truck a Christmas present.
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1948 Chevy 1/2T 1964 Chevy 1/2T stepside short bed 1939 Pontiac coupe Street Rod 2005 GMC 1/2T short bed |
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#10 |
Registered User
Join Date: Feb 2013
Location: Cottonwood, Arizona
Posts: 1,376
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Re: Gas gauge issue
Hi everybody, and Happy New Year.
Sorry for breaking in on this thread but I have an issue with my gas gauge too. When my tank is full, it is steady, but when it gets to about half, the needle starts going back and forth like crazy. I have removed the tank a few times, and the tube is a little loose and I've had to bolt the wire on to the senser. I'm afraid all the fluctuating is going to damage my gauge. Any ideas of why it's doing this? The ground is good. The one positive about it is when my guage reads 1/4 I still have almost a half tank. Thanks in advance for any help and advice. |
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#11 |
State of Confusion!
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Location: Gulfport, MS USA
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Re: Gas gauge issue
The swaying gas gauge is fairly normal. These tanks have no baffles and the gas moves around a good bit, thus giving the moving gauge syndrome. You kinda lkearn how the swing is compared to how much fuel is left.
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Bill 1970 Chevy Custom/10 LWB Fleetside 2010 Toyota Tacoma PreRunner SR5 Double Cab - DD Member of Louisiana Classic Truck Club (LCTC) Bill's Gallery Life isn't tied with a bow, but it's still a gift. Live simply. Love generously. Care deeply. Speak kindly. Leave the rest to God! |
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#12 |
Registered User
Join Date: Feb 2013
Location: Cottonwood, Arizona
Posts: 1,376
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Re: Gas gauge issue
palf70step
Thanks for the reply. The needle osnt judt swaying, it's really fluttering back and forth. It never did this until I removed the sender a few times. Even on my original sender after zip-tying the housing together, it didnt do the fluttering. Could it be because the intake tube is loose? I've JB weld it to the flange but it broke loose again. |
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#13 |
Senior Member
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Location: new smyrna beach fl / 29 palms cal
Posts: 1,727
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Re: Gas gauge issue
I had a 65 f100 with a 4 camer in it the pomp was in the tank the gas gage did not work so I got to know how much gas I had by how fast I could turn the corner
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#14 | |
State of Confusion!
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Location: Gulfport, MS USA
Posts: 46,929
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Re: Gas gauge issue
Quote:
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Bill 1970 Chevy Custom/10 LWB Fleetside 2010 Toyota Tacoma PreRunner SR5 Double Cab - DD Member of Louisiana Classic Truck Club (LCTC) Bill's Gallery Life isn't tied with a bow, but it's still a gift. Live simply. Love generously. Care deeply. Speak kindly. Leave the rest to God! |
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