YJ Fuel Gauge - Jeep Wrangler Forum
Jeep Wrangler Forum

Go Back   Jeep Wrangler Forum > YJ Jeep Wrangler Forum > YJ Tech Forum

Join Wrangler Forum Today


Reply
 
Thread Tools

Please support our sponsors and let them know you heard about them on WranglerForum.com
Old 05-31-2011, 12:32 PM   #1
Newb
 
Join Date: Feb 2011
Posts: 5
YJ Fuel Gauge

Hi Guys & Gals
Is the fuel gauge in a 93 YJ supposed to go down to "E" when the ignitions off or are they supposed to stay at whatever level is currently in the tank?? Also, My fuel gauge will only register from half upwards, once it reaches half it just sticks there. I got a replacement set of clocks for it to do exactly the same
Any pointers in the right direction would be cool!!

YJ Pluto is offline   Quote Quick Reply
Old 05-31-2011, 01:39 PM   #2
Jeeper
 
Undead-89's Avatar
 
Join Date: Feb 2011
Location: Loveland, CO
Posts: 760
Mine did that for years. I cleaned the contacts and the flexible board behind it and now it goes down to 1/4 tank. Mine does drop down to E when I turn off the Jeep. In fact, all my gauges drop to zero when the ignition is off. Except the clock. mine also has a needle that bobs all over the place, When it stops moving I know I need Gas right away.

If the float is bent or the the tank is dented in the bottom that will also change the reading. but i would start with clean contacts first.

Undead-89 is offline   Quote Quick Reply
Old 05-31-2011, 01:54 PM   #3
Newb
 
Join Date: Feb 2011
Posts: 5
Cool, Thanks Mister. Is there any way i can test the wiring at the back of the clocks with a multi-meter? Id rather start that end before dropping the tank and assuming the expensive bits are at fault
YJ Pluto is offline   Quote Quick Reply
Old 05-31-2011, 03:00 PM   #4
Jeeper
 
Undead-89's Avatar
 
Join Date: Feb 2011
Location: Loveland, CO
Posts: 760
Yes and no. You can test it, that isn't a problem, but I don't know what the voltage levels are that you would be looking for at a given point. I'm also not sure how linear the gauges are.

Basically, you have a variable resistor (AKA Potentiometer) called the fuel gauge sender connected to the arm in the tank. As the arm moves it changes the resistance of the pot which changes the voltage output. You can assume 0 volts is empty because the needle drops that way when the power is off.

The Sender is grounded at one end and connected to the gauge at the other. the voltages are supplied in the gauge itself. if the problem is purely electrical, somewhere you have too much resistance. The most common cause of unwanted resistance is corrosion. Either the contacts at the gauge, the contacts at the sender or in the potentiometer.

The only way I know of to test the Gauge would be to have a collection of Potentiometers of a know value, ground one end to the chassis and connect the middle connector to the S on the gauge after removing the sender from the circuit. with the gauge powered you should see the needle move. Adjust it to Empty on the gauge, remove the pot and measure the resistence (ohms) across those two points. reconnect, adjust to full, disconnect and measure. this will get your minimum and maximum values for the sender. if it doesn't reach empty or full you need a higher value test pot.

Once you have the min and max you start working down the circuit (unpowered) and see where the resistance changes. Easy in the dash, hard at the tank.

If you replaced the gauges with after market gauges, they MAY have an adjustment. I think the originals do but it is on the rear of the gauge and covered usually.

There are two ways to do an adjustment to where you think the level should be. one, is hit or miss. turn the adjustment screw. hook it back up, see where it is and repeat till you get it right or give up and get it good enough. you can do this with the tank full, you are just going to move the needle back from overfull until it is just on F. Though it still might not be perfect.

The second way, is to get your tank to empty, measure the resistance from the sender. Set up a small power supply to the gauge At I (+) and G (-, ground) on a bench. Adjust your variable pot to the same value as the sender and connect it between the S on the gauge and the - ground on the power supply. Adjust the adjustment screw until the needle sits at E. I would adjust the pot now and make sure the needle moves toward full.

Hit or miss might be just as easy, or easier than emptying the tank.
Undead-89 is offline   Quote Quick Reply
Old 04-07-2012, 02:10 AM   #5
Newb
 
meansnake1's Avatar
 
Join Date: Mar 2012
Location: Eastern NC
Posts: 4
Hey every one. I'm the new guy getting a 1991 yj going again. Saved it from a mudder who gutted the interior including the roll bar, and didn't change the oil for a few years. My fuel gage only reads down to 3/4 of a tank when it's walking time. Would a dented tank cause this? My skid plate under the tank looks undamaged, and I got 215 miles out of my tank before the community watch guy checked to see if the police officer in uniform carrying a fuel can and flashlight was a prowler.
meansnake1 is offline   Quote Quick Reply
Old 04-07-2012, 07:31 AM   #6
Jeeper
 
Join Date: Dec 2011
Posts: 81
How do you clean the contacts behind the gauge???
VeroJoe is offline   Quote Quick Reply
Old 04-14-2012, 01:09 PM   #7
Jeeper
 
Join Date: Nov 2011
Location: Winston-Salem, NC
Posts: 162
I am curious too! Bump!
__________________
88 Wrangler SOA lift with Waggy Springs supporting an AMC 360, and ax15 5spd Transmission. She is a work in progress!!!! Every little fix is a victory!
deepair3 is offline   Quote Quick Reply
Old 04-14-2012, 01:39 PM   #8
Supporting Member

WF Supporting Member
 
Bobinayj's Avatar
 
Join Date: Jan 2012
Location: Pie Town, New Mexico
Posts: 57
After a few years, the gauge in my 93 YJ never went below 1/4. Turns out the plastic fuel tanks can warp over time, causing the bottom to bow up giving inacurate readings. I replaced the tank, and problem solved.
__________________
93 YJ still has a few original parts - very few
Bobinayj is offline   Quote Quick Reply
Old 04-15-2012, 06:15 AM   #9
Jeeper
 
Join Date: Nov 2011
Location: Winston-Salem, NC
Posts: 162
I cleaned the contacts on the back of the guages and now she seems to work just fine!
__________________
88 Wrangler SOA lift with Waggy Springs supporting an AMC 360, and ax15 5spd Transmission. She is a work in progress!!!! Every little fix is a victory!
deepair3 is offline   Quote Quick Reply
Old 04-15-2012, 12:46 PM   #10
Jeeper
 
Nas.a7x's Avatar
 
Join Date: Aug 2011
Posts: 1,108
I got a dent in the bottom of my tank.. didn't think of that causing the problem it won't go down below 1/4 to 1/8 so I guess that's one more thing that I will b replacing when the timming is right

Nas.a7x is offline   Quote Quick Reply
Reply

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Jeep Wrangler Forum forums, you must first register.
Please enter your desired user 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.



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 Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
Fuel Gauge Inoperable at times 1HOTV2 TJ General Discussion Forum 6 06-28-2011 09:58 PM
Fuel sender and Fuel gauge wiring - no fuel chiefshocker YJ Tech Forum 4 05-24-2011 07:02 PM
The effects of ethanol gas on a Jeep 95jeepthing YJ General Discussion Forum 37 12-28-2010 05:31 PM
Aftermarket fuel gauge not reading full ctclark1 YJ Tech Forum 3 03-31-2008 01:44 PM



» Network Links
»Jeep Parts
» Featured Product

All times are GMT -5. The time now is 02:26 PM.



Jeep®, Wrangler, Liberty, Wagoneer, Cherokee, and Grand Cherokee are copyrighted and trademarked to Chrysler Motors LLC.
Wranglerforum.com is not in any way associated with the Chrysler Motors LLC