Fuel gauge not working correctly - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Electrical
User Name
Password
lost password?   |   register now

Reply
 
LinkBack Thread Tools
  #1 (permalink)  
Old 02-28-2013, 10:06 AM
Registered User
 
Join Date: Aug 2012
Posts: 9
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Fuel gauge not working correctly

65 gmc, fuel gauge is stuck on full any suggestions
Reply With Quote Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 02-28-2013, 11:08 AM
Registered User
 
Join Date: Aug 2012
Posts: 9
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
It's a fairly new sending unit. Only way to get fuel gauge to move is putting a ground on the hot wire. Then the gauge jumps almost to half and then bak to full...wiring problem?
Reply With Quote Quick reply to this message
  #3 (permalink)  
Old 02-28-2013, 11:46 AM
vicrod's Avatar
life is a ride
 

Last journal entry: LED tail lights
Last photo:
Join Date: Nov 2005
Location: Telford, PA
Age: 71
Posts: 1,235
Wiki Edits: 0

Thanks: 0
Thanked 45 Times in 41 Posts
When the sending unit was replaced did the gauge work OK?
Make sure the sending unit is grounded. Sometimes the rust builds up an breaks the ground path to the chassis.

vicrod
Reply With Quote Quick reply to this message
  #4 (permalink)  
Old 02-28-2013, 11:57 AM
sedanbob's Avatar
Registered User
 
Last photo:
Join Date: Oct 2008
Location: St. Louis
Age: 65
Posts: 625
Wiki Edits: 0

Thanks: 60
Thanked 80 Times in 77 Posts
Try running a dedicated ground from a clean spot on the chassis to one of the bolts on the sending unit flange. See if that helps.
Reply With Quote Quick reply to this message
  #5 (permalink)  
Old 02-28-2013, 05:16 PM
NEW INTERIORS's Avatar
Believe in yourself !!!!!!
 

Last journal entry: 41 WILLYS FRAME
Last photo:
Join Date: Jul 2007
Location: In My Shop..
Age: 48
Posts: 9,811
Wiki Edits: 0

Thanks: 987
Thanked 429 Times in 326 Posts
Quote:
Originally Posted by klassickarman View Post
It's a fairly new sending unit. Only way to get fuel gauge to move is putting a ground on the hot wire. Then the gauge jumps almost to half and then bak to full...wiring problem?
What hot wire ???

The wire going to the tank( sending unit) SHOULD NOT be hot.. Make sure the tank has a ground...
Reply With Quote Quick reply to this message
  #6 (permalink)  
Old 02-28-2013, 06:31 PM
Registered User
 
Last photo:
Join Date: Mar 2010
Location: georgia
Posts: 77
Wiki Edits: 0

Thanks: 0
Thanked 11 Times in 10 Posts
The wire going to the sending unit has to be hot, it grounds through the sending units variable resistance to operate the gauge. Your trucks system should be 0-90 ohm type. If you ground the sending unit wire, the gauge should read zero and stay there. If you connect a 90 ohm resistor between the wire and ground, it should read full. (you probably won't find a 90 ohm resistor, but you can get a 100 ohm from Radio Shack and it will get you in the ball park) This will tell you if the gauge is working.
As has been previously said, you need to make sure the sending unit is grounded properly. If it still doesn't work, you need to pull the sending unit, connect an ohmeter to it and make sure the resistance changes between 0 and 90 ohms as you move the float arm.
Reply With Quote Quick reply to this message
  #7 (permalink)  
Old 02-28-2013, 06:43 PM
NEW INTERIORS's Avatar
Believe in yourself !!!!!!
 

Last journal entry: 41 WILLYS FRAME
Last photo:
Join Date: Jul 2007
Location: In My Shop..
Age: 48
Posts: 9,811
Wiki Edits: 0

Thanks: 987
Thanked 429 Times in 326 Posts
Quote:
Originally Posted by sparkchaser View Post
The wire going to the sending unit has to be hot, it grounds through the sending units variable resistance to operate the gauge. Your trucks system should be 0-90 ohm type. If you ground the sending unit wire, the gauge should read zero and stay there. If you connect a 90 ohm resistor between the wire and ground, it should read full. (you probably won't find a 90 ohm resistor, but you can get a 100 ohm from Radio Shack and it will get you in the ball park) This will tell you if the gauge is working.
As has been previously said, you need to make sure the sending unit is grounded properly. If it still doesn't work, you need to pull the sending unit, connect an ohmeter to it and make sure the resistance changes between 0 and 90 ohms as you move the float arm.
How do you ground a hot wire..

Never seen a hot wire going to a sender unit..I have seen a hot feeding the gauge,, But never a hot going to a FUEL sender..
Reply With Quote Quick reply to this message
  #8 (permalink)  
Old 02-28-2013, 06:50 PM
NEW INTERIORS's Avatar
Believe in yourself !!!!!!
 

Last journal entry: 41 WILLYS FRAME
Last photo:
Join Date: Jul 2007
Location: In My Shop..
Age: 48
Posts: 9,811
Wiki Edits: 0

Thanks: 987
Thanked 429 Times in 326 Posts
Quote:
Originally Posted by klassickarman View Post
65 gmc, fuel gauge is stuck on full any suggestions
What ever you do.. PLEASE DO NOT !!!!!! run a hot wire to the sender unit..
Reply With Quote Quick reply to this message
  #9 (permalink)  
Old 02-28-2013, 07:21 PM
Registered User
 
Last photo:
Join Date: Mar 2010
Location: georgia
Posts: 77
Wiki Edits: 0

Thanks: 0
Thanked 11 Times in 10 Posts
Maybe we have a misunderstanding here, but the power you put into a gauge comes out of the gauge and goes to the sending unit where the variable resistance causes the needle to move. if you connect a voltmeter to the sending unit, you will read voltage. If the wire is not hot, how is the sending unit going to operate the gauge?
Reply With Quote Quick reply to this message
  #10 (permalink)  
Old 02-28-2013, 07:31 PM
NEW INTERIORS's Avatar
Believe in yourself !!!!!!
 

Last journal entry: 41 WILLYS FRAME
Last photo:
Join Date: Jul 2007
Location: In My Shop..
Age: 48
Posts: 9,811
Wiki Edits: 0

Thanks: 987
Thanked 429 Times in 326 Posts
Quote:
Originally Posted by sparkchaser View Post
Maybe we have a misunderstanding here, but the power you put into a gauge comes out of the gauge and goes to the sending unit where the variable resistance causes the needle to move. if you connect a voltmeter to the sending unit, you will read voltage. If the wire is not hot, how is the sending unit going to operate the gauge?
It work's through a ground, Not a hot.. Why do you think when you ground it, It moves the gauge..... You should be very careful posting to the world to run a hot wire to a FUEL sender unit,,, You might just cause someone to get hurt or even worst blown up...

Think of it like this.. Take a hot wire and ground it... You will short it out... The hot only feed's the gauge,, Not the sender,,, The gauge doesn't work until you make a ground.. The sender makes and breaks the ground,, That's why the tank needs a ground for the sender to work right..

I see now how you came up with the name sparkchaser...Fun intended..

Last edited by NEW INTERIORS; 02-28-2013 at 07:37 PM.
Reply With Quote Quick reply to this message
  #11 (permalink)  
Old 02-28-2013, 08:40 PM
Registered User
 
Last photo:
Join Date: Mar 2010
Location: georgia
Posts: 77
Wiki Edits: 0

Thanks: 0
Thanked 11 Times in 10 Posts
I never said to run a hot wire to the sender. I said the wire coming from the gauge is hot, it has voltage on it. Pull the wire off your sending unit, connect a voltmeter to it and you will be amazed.
Reply With Quote Quick reply to this message
  #12 (permalink)  
Old 02-28-2013, 08:51 PM
NEW INTERIORS's Avatar
Believe in yourself !!!!!!
 

Last journal entry: 41 WILLYS FRAME
Last photo:
Join Date: Jul 2007
Location: In My Shop..
Age: 48
Posts: 9,811
Wiki Edits: 0

Thanks: 987
Thanked 429 Times in 326 Posts
Quote:
Originally Posted by sparkchaser View Post
I never said to run a hot wire to the sender. I said the wire coming from the gauge is hot, it has voltage on it. Pull the wire off your sending unit, connect a voltmeter to it and you will be amazed.
Look's like you said it here..

That would be post #6

Quote:
Originally Posted by sparkchaser View Post
The wire going to the sending unit has to be hot,
Reply With Quote Quick reply to this message
  #13 (permalink)  
Old 02-28-2013, 08:56 PM
NEW INTERIORS's Avatar
Believe in yourself !!!!!!
 

Last journal entry: 41 WILLYS FRAME
Last photo:
Join Date: Jul 2007
Location: In My Shop..
Age: 48
Posts: 9,811
Wiki Edits: 0

Thanks: 987
Thanked 429 Times in 326 Posts
Quote:
Originally Posted by sparkchaser View Post
I never said to run a hot wire to the sender. I said the wire coming from the gauge is hot, it has voltage on it. Pull the wire off your sending unit, connect a voltmeter to it and you will be amazed.
Here's something you may need to read when you have time...Pick one..
Google
Reply With Quote Quick reply to this message
  #14 (permalink)  
Old 02-28-2013, 09:14 PM
NEW INTERIORS's Avatar
Believe in yourself !!!!!!
 

Last journal entry: 41 WILLYS FRAME
Last photo:
Join Date: Jul 2007
Location: In My Shop..
Age: 48
Posts: 9,811
Wiki Edits: 0

Thanks: 987
Thanked 429 Times in 326 Posts
Here's a good write up...The GM Fuel Gauge Mystery 1965 & Newer |
Reply With Quote Quick reply to this message
  #15 (permalink)  
Old 03-01-2013, 08:51 AM
sedanbob's Avatar
Registered User
 
Last photo:
Join Date: Oct 2008
Location: St. Louis
Age: 65
Posts: 625
Wiki Edits: 0

Thanks: 60
Thanked 80 Times in 77 Posts
When the ignition is on, and your gauge is reading (full, empty, half way, doesn't matter) current is flowing through the sender. Yes, the sender is on the ground side of the gauge, but if there wasn't current flowing through the sender you wouldn't get a reading. As was stated earlier, if you put one lead from a volt meter on the lead going to the sender, and the other lead going to a ground, you will measure voltage. The sender body is in contact with the tank, which is in contact with the frame, thereby grounded - but those connections may not be electrically clean. If you jump a wire from a bolt on the sender flange, to a clean spot on the frame and the gauge then works, the problem was a poor ground.
Reply With Quote Quick reply to this message

Recent Electrical posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
Petrol gauge not working skylimt Electrical 1 01-02-2012 08:49 AM
Fuel gauge not working... Hwyhogg Electrical 7 11-16-2011 09:52 AM
Gas gauge not working gothrod87 Electrical 4 06-01-2005 07:26 AM
Question about Temp-gauge not working??? Robbie Engine 4 06-13-2004 07:47 PM


All times are GMT -6. The time now is 11:26 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.