Bouncing gas gauge qustion - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Desert1957 · 07-27-2013, 08:49 AM

Thread should say "question"

My 83 has dual tanks, after fuel level gets down below 3/4 the gauge seem to be constantly moving around and bouncing. Is there a fix for this? or is it a common problem.

My 87 with the electric fuel pump takes a different sender I know, but does not have any issues with the gauge.

Desert

Ziegelsteinfaust · 07-27-2013, 11:21 AM

Mine has a similar problem, and I think the problem is the sending unit on mine.

**hatzie** · 07-27-2013, 01:13 PM

Solid tank and gauge grounds and solid sender wire connections...

INSIDIOUS '86 · 07-27-2013, 02:24 PM

I think the fuel just sloshes around more when low

As I recall some gas gauges had a resistor to move slower to prevent bouncing
Posted via Mobile Device

Skunksmash · 07-27-2013, 05:09 PM

GM really screwed the pooch on this one. Not only did they mess up on the gauge side of things, they messed up on the sending unit side as well. The way I fixed it, was to buy a gauge from autometer. It won't accept the wildly fluctuating 0-90 ohm signal from the sending unit, so easily. It waits before it adjusts the needle. This cuts out most of the wavy needle problem, though you will still see it move from time to time.

To truly fix the problem, you also have to get a tank with better baffles in it, such as the newer ones with that big piece of foam in there.

http://www.chevyclassicsclub.com/the...ry-1965-newer/

Desert1957 · 07-28-2013, 07:21 AM

Quote:

Originally Posted by Skunksmash

GM really screwed the pooch on this one. Not only did they mess up on the gauge side of things, they messed up on the sending unit side as well. The way I fixed it, was to buy a gauge from autometer. It won't accept the wildly fluctuating 0-90 ohm signal from the sending unit, so easily. It waits before it adjusts the needle. This cuts out most of the wavy needle problem, though you will still see it move from time to time.

To truly fix the problem, you also have to get a tank with better baffles in it, such as the newer ones with that big piece of foam in there.

http://www.chevyclassicsclub.com/the...ry-1965-newer/

Nice article

slam59 · 07-28-2013, 12:30 PM

My wife's 77 3/4 ton with dual tanks does the same thing. That needle bounces all over the place ALL the time. Gonna have to try that Autometer gauge.

PAWS 72 · 07-29-2013, 02:01 AM

I was thinking bad ground or connection.I've been wrong before too.

motornut · 07-29-2013, 10:15 AM

When i got my 78 Jimmy it did this
I read up on it decided to live with it
when i changed to the stock cluster with tach, it went away
when i wired the cluster up i had to add a ground for the gauge

Skunksmash · 07-30-2013, 07:21 PM

Quote:

Originally Posted by Desert1957

Nice article

Yeah I used to hate that dang wavy needle. Its like not even having a gas gauge lol. There are some people that claim you can get lucky buying a high quality, ACdelco brand sending unit (that whole apparatus) and it will fix the wavy needle. Some have done it and got lucky, others bought the same thing and had no results.

I like the idea about the ground. I always thought there had to be a way to let the signal through, but just do it once per minute. Instead of 6 times a second. That way, the needle would seldom ever be seen moving, but the gauge would still work just fine.

motornut · 07-30-2013, 09:34 PM

just to add
it was idiots to tach/gauges in the 78
i read people had issues with spectra senders
I can see a spectra stamp on the 78 tank assumed it was a spectra sender
but in the 79 I went with a spectra tank and sender and it didn't bounce before or after
Posted via Mobile Device

07-27-2013, 08:49 AM	#1
Desert1957 Registered User Join Date: Apr 2009 Location: New Freedom Pa. Posts: 1,335	Bouncing gas gauge qustion Thread should say "question" My 83 has dual tanks, after fuel level gets down below 3/4 the gauge seem to be constantly moving around and bouncing. Is there a fix for this? or is it a common problem. My 87 with the electric fuel pump takes a different sender I know, but does not have any issues with the gauge. Desert

07-27-2013, 11:21 AM	#2
Ziegelsteinfaust Registered User Join Date: Dec 2012 Location: Temple City Posts: 3,586	Re: Bouncing gas gauge qustion Mine has a similar problem, and I think the problem is the sending unit on mine.

07-27-2013, 01:13 PM	#3
hatzie Moderator Join Date: Oct 2008 Location: Wentworth, NH Posts: 4,950	Re: Bouncing gas gauge qustion Solid tank and gauge grounds and solid sender wire connections... __________________ 1959 M35A2 LDT465-1D SOLD 1967 Dodge W200 B383, NP420/NP201 SOLD 1969 Dodge Polara 500 B383, A833 SOLD 1972 Ford F250 FE390, NP435/NP205 SOLD 1976 Chevy K20, 6.5L, NV4500/NP208 SOLD 1986 M1008 CUCV SOLD 2000 GMC C2500, TD6.5L, NV4500 2005 Chevy Silverado LS 2500HD 6.0L 4L80E/NP263 2009 Impala SS LS4 V8 RTFM... GM Parts Books, GM Schematics, GM service manuals, and GM training materials... 1973-1991 GM Light Truck Service, Unit/Overhaul, Wiring Manuals, Parts Books and Some 1968-1999 GM Service Training textbooks in PDF 1988-1998 GMT400 CK service manual project 1988-1993 GMT400 CK parts books. 1967-1972 GM Light, Medium, & Heavy Truck Service Manuals in PDF Please include at least the year and model in your threads. It'll be easier to answer your questions. And please let us know if and how your repairs were successful.

07-27-2013, 02:24 PM	#4
INSIDIOUS '86 Registered User Join Date: Jul 2009 Location: washington Posts: 4,178	Re: Bouncing gas gauge qustion I think the fuel just sloshes around more when low As I recall some gas gauges had a resistor to move slower to prevent bouncing Posted via Mobile Device __________________ 377 sbc thumpr cam autogear m23 muncie 3:73 Detroit trutrac 3''spintech prostreet mufflers xpipe 1 3/4 headers build thread !http://67-72chevytrucks.com/vboard/s...d.php?t=577217 Iroc gauge threadhttp://67-72chevytrucks.com/vboard/s...d.php?t=554511

07-27-2013, 05:09 PM	#5
Skunksmash Registered User Join Date: Sep 2012 Location: TX Posts: 1,014	Re: Bouncing gas gauge qustion GM really screwed the pooch on this one. Not only did they mess up on the gauge side of things, they messed up on the sending unit side as well. The way I fixed it, was to buy a gauge from autometer. It won't accept the wildly fluctuating 0-90 ohm signal from the sending unit, so easily. It waits before it adjusts the needle. This cuts out most of the wavy needle problem, though you will still see it move from time to time. To truly fix the problem, you also have to get a tank with better baffles in it, such as the newer ones with that big piece of foam in there. http://www.chevyclassicsclub.com/the...ry-1965-newer/

07-28-2013, 12:30 PM	#7
slam59 Registered User Join Date: Nov 2011 Location: So. Calif Posts: 305	Re: Bouncing gas gauge qustion My wife's 77 3/4 ton with dual tanks does the same thing. That needle bounces all over the place ALL the time. Gonna have to try that Autometer gauge. __________________ 1974 C10 swb 350 1977 3/4 ton Silverado 454 1999 2 door 2wd Tahoe

07-29-2013, 02:01 AM	#8
PAWS 72 Registered User Join Date: Nov 2011 Location: Sheffield, ALA Posts: 2,471	Re: Bouncing gas gauge qustion I was thinking bad ground or connection.I've been wrong before too.

07-29-2013, 10:15 AM	#9
motornut 78K & 79C Jimmys Join Date: Nov 2009 Location: Ottawa Ont CANADA Posts: 7,901	Re: Bouncing gas gauge qustion When i got my 78 Jimmy it did this I read up on it decided to live with it when i changed to the stock cluster with tach, it went away when i wired the cluster up i had to add a ground for the gauge __________________ John 1978 GMCJimmy4X4-350/203 1979 GMCJimmy4X2-305/350

07-30-2013, 09:34 PM	#11
motornut 78K & 79C Jimmys Join Date: Nov 2009 Location: Ottawa Ont CANADA Posts: 7,901	Re: Bouncing gas gauge qustion just to add it was idiots to tach/gauges in the 78 i read people had issues with spectra senders I can see a spectra stamp on the 78 tank assumed it was a spectra sender but in the 79 I went with a spectra tank and sender and it didn't bounce before or after Posted via Mobile Device __________________ John 1978 GMCJimmy4X4-350/203 1979 GMCJimmy4X2-305/350



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