Fuel Guage reads past full all the time? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Suicide-D · 10-25-2003, 07:27 PM

Ok I looked behind the seat and only have one tan wire coming off of the sender. The tan wire that comes out at the top of the fuse block that says fuel guage is cut off about 6" from the fuse block... where does it go?

EDIT: I followed the tan wire from the sending unit and it goes past the floor mounted dimmer switch...there is an electrical taped splice... then it goes out the firewall and what looks like into the back of the fuse block...

how is this supposed to be??

**68 Stepside** · 10-25-2003, 08:16 PM

Wow, that's strange. Do you have underbed tanks that had senders or something? Maybe that's why the wire is going out of the cab? My fuel gauge wire goes from the sending unit through that light brown (tan) wire, to the "fuel gauge" spot on the fuse box. Try hooking the sender to that and see what happens.

Good luck.

dinnut · 10-25-2003, 08:19 PM

i have the same problem. i think its the sender on mine. the tan wire goes off the sender and under the bondo rocker. it was cut before the rocker and we taped it but nothing happened.

gonebad2 · 10-25-2003, 08:27 PM

I once had the same problem. Turned out to be a bad sending unit. Took it apart and looked at it. There are some very fine wires wound around what looked like a small piece of white plastic. A brass tab makes contact with the fine wires. One of the fine wires was broken. Installed a new sending unit and it worked just fine.

blue_69 · 10-25-2003, 08:32 PM

It could be that your sender is not grounded good enough. This will cause your gauge to work but read from about half when its empty and way past full when its full.

good luck,
jason

my new 72 · 10-25-2003, 08:41 PM

The sender wire is just not connected to the propper spot on the fuse box. Or you could just bypass the fuse block all together and just run the wire directly from the tan sending unit wire to the plug on the back of the gauges. Give me a call and I'll WALK you through the diagram to make sure you get it right the first time. We wouldn't want another suicide door incident.lol Here is the link to the diagram, http://www.geocities.com/chevroletc1070/instrum2.html

Suicide-D · 10-25-2003, 09:51 PM

ha... no we wouldn't....I'm fixing that now. I'll mess with the sender on sunday

Suicide-D · 10-26-2003, 06:30 PM

Well, I must have a bad float / sender or something. I hooked up the wire and it goes to empty and stays. I went and put gas in it to make sure it just wasn't empty... and same result..stays on empty... How big of a pain is it to pull that unit out of the tank?

Dean23 · 10-26-2003, 06:36 PM

maybe u r just getting really good fuel economy...nah sounds like maybe a bad ground

my new 72 · 10-26-2003, 06:44 PM

It's not that hard. That ring on the top is like a pressure slip ring. Use a screw driver to tap it around the opposite of the tabs it is up against now and it will pop up when it gets to the openings. If not, just gently pry it up with a screw driver. Then it's ready to pull out.

Duallie · 10-27-2003, 01:14 PM

FYI: When a fuel level gauge always reads "full", the connection is broken somewhere. Perpetual "empty" means a short to ground before the sender.

lukecp · 10-27-2003, 01:16 PM

Test the sender before you replace it....pull it out, and hook up a ohm meter to the connection for the unit, and move the float up and down. The resistance should change....i'm thinking 30-90ohms total.

Suicide-D · 10-27-2003, 08:13 PM

the float is full gas.... my multimeter was acting stupid but the float is definitely full. the needle on the meter was jumping all over the place

**'68OrangeSunshine** · 10-28-2003, 05:38 AM

A new brass float will run you $5 from any vendor.

10-25-2003, 07:27 PM	#1
Suicide-D Registered User Join Date: Jan 2001 Location: Katy, TX...but the love of my life resides in Dublin,OH. Posts: 1,408	Fuel Guage reads past full all the time? Ok I looked behind the seat and only have one tan wire coming off of the sender. The tan wire that comes out at the top of the fuse block that says fuel guage is cut off about 6" from the fuse block... where does it go? EDIT: I followed the tan wire from the sending unit and it goes past the floor mounted dimmer switch...there is an electrical taped splice... then it goes out the firewall and what looks like into the back of the fuse block... how is this supposed to be?? Last edited by Suicide-D; 10-25-2003 at 07:49 PM.

10-25-2003, 08:16 PM	#2
68 Stepside huh? Join Date: May 2000 Location: Washington, Illinois Posts: 5,692	Wow, that's strange. Do you have underbed tanks that had senders or something? Maybe that's why the wire is going out of the cab? My fuel gauge wire goes from the sending unit through that light brown (tan) wire, to the "fuel gauge" spot on the fuse box. Try hooking the sender to that and see what happens. Good luck. __________________ Someday when I'm lonely, Wishing you weren't so far away, Then I will remember Things we said today. RIP El Jay

10-25-2003, 08:19 PM	#3
dinnut Registered User Join Date: Apr 2003 Location: missouri city, tx Posts: 4,486	i have the same problem. i think its the sender on mine. the tan wire goes off the sender and under the bondo rocker. it was cut before the rocker and we taped it but nothing happened. __________________ 70 longbed 496/th400/Ford 9"

10-25-2003, 08:27 PM	#4
gonebad2 Merciless Butcher Join Date: Oct 2003 Location: CC Nevada Posts: 1,447	I once had the same problem. Turned out to be a bad sending unit. Took it apart and looked at it. There are some very fine wires wound around what looked like a small piece of white plastic. A brass tab makes contact with the fine wires. One of the fine wires was broken. Installed a new sending unit and it worked just fine. __________________ Your Bought And Sold....I Got Your Soul!

10-25-2003, 08:32 PM	#5
blue_69 someday Join Date: Dec 2001 Location: canastota,new york Posts: 629	It could be that your sender is not grounded good enough. This will cause your gauge to work but read from about half when its empty and way past full when its full. good luck, jason __________________ Click Here to search ebay for all 67-72 parts My 72 CST blazer build 72 CST Blazer 4x4 67 2wd swb ( project onion crate ) 86 4x4 lwb plow truck 40 x 60 foot barn to work on all this stuff

10-25-2003, 08:41 PM	#6
my new 72 faster, faster, faster Join Date: Dec 2001 Location: Houston ,Texas ,USA Posts: 1,354	The sender wire is just not connected to the propper spot on the fuse box. Or you could just bypass the fuse block all together and just run the wire directly from the tan sending unit wire to the plug on the back of the gauges. Give me a call and I'll WALK you through the diagram to make sure you get it right the first time. We wouldn't want another suicide door incident.lol Here is the link to the diagram, http://www.geocities.com/chevroletc1070/instrum2.html __________________ I'm going to Law School, wanna debate? It's good practice.

10-25-2003, 09:51 PM	#7
Suicide-D Registered User Join Date: Jan 2001 Location: Katy, TX...but the love of my life resides in Dublin,OH. Posts: 1,408	ha... no we wouldn't....I'm fixing that now. I'll mess with the sender on sunday

10-26-2003, 06:30 PM	#8
Suicide-D Registered User Join Date: Jan 2001 Location: Katy, TX...but the love of my life resides in Dublin,OH. Posts: 1,408	Well, I must have a bad float / sender or something. I hooked up the wire and it goes to empty and stays. I went and put gas in it to make sure it just wasn't empty... and same result..stays on empty... How big of a pain is it to pull that unit out of the tank?

10-26-2003, 06:36 PM	#9
Dean23 68cst_ss490 Join Date: May 2001 Location: edmonton,canada Posts: 1,363	maybe u r just getting really good fuel economy...nah sounds like maybe a bad ground __________________ Dean edmonton,canada a winter wonderland 2005 Chevrolet Avalanche LT cold air intake, performance exhaust, Comp cams cam, jba shorty ceramic headers. http://www.cardomain.com/ride/3090973

10-26-2003, 06:44 PM	#10
my new 72 faster, faster, faster Join Date: Dec 2001 Location: Houston ,Texas ,USA Posts: 1,354	It's not that hard. That ring on the top is like a pressure slip ring. Use a screw driver to tap it around the opposite of the tabs it is up against now and it will pop up when it gets to the openings. If not, just gently pry it up with a screw driver. Then it's ready to pull out. __________________ I'm going to Law School, wanna debate? It's good practice.

10-27-2003, 01:14 PM	#11
Duallie Registered User Join Date: Feb 2001 Location: Nikiski, Alaska Posts: 477	FYI: When a fuel level gauge always reads "full", the connection is broken somewhere. Perpetual "empty" means a short to ground before the sender. __________________ Just as if I knew what I was doin'

10-27-2003, 01:16 PM	#12
lukecp Formerly yellow72custom Join Date: May 2001 Location: Austin, TX Posts: 7,531	Test the sender before you replace it....pull it out, and hook up a ohm meter to the connection for the unit, and move the float up and down. The resistance should change....i'm thinking 30-90ohms total. __________________ '72 Chevy C10 Mild 350/TH350/3.07. Ochre/White. Old high school ride. '70 GMC C2500 '62 327 4bbl/SM465/4.56-geared Dana 60. White/White. Project or parts truck. '97 Saturn SL DD. 1.9/5-speed. 40+ highway mpg

10-27-2003, 08:13 PM	#13
Suicide-D Registered User Join Date: Jan 2001 Location: Katy, TX...but the love of my life resides in Dublin,OH. Posts: 1,408	the float is full gas.... my multimeter was acting stupid but the float is definitely full. the needle on the meter was jumping all over the place

10-28-2003, 05:38 AM	#14
'68OrangeSunshine Senior Member Join Date: Feb 2002 Location: Tucson, AZ USA Posts: 7,205	A new brass float will run you $5 from any vendor. Last edited by '68OrangeSunshine; 10-28-2003 at 05:40 AM.



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