Moparchat - Home of MOPAR enthusiasts worldwide!



Go Back   Moparchat - Home of MOPAR enthusiasts worldwide! > Technical Forums > Restoring your MoPar (Tricks & techniques)

Click here to search for Mopar cars and parts for sale.


Reply
 
Thread Tools Display Modes
  #1  
Old 05-27-2003, 11:23 AM
TOOL MAN's Avatar
TOOL MAN TOOL MAN is offline
Inactive User
 
Join Date: May 1999
Location: GREAT STATE OF MO.
Posts: 161
Default fuel sending unit problems

Well let me start by saying that i have a 66 coronet 440 with the poly 318. the problem i have is that the replacement sending unit i bought from layson's has given me day after day of head aches. the problem is that the guage only moves to the empty mark when it has power. continuity is good, when the leads are given a direct ground the guage reads full. under a test light it does give the pulse voltage as it should.

with the sending unit out of the tank, using the same indipendant ground and power, i can move the float arm and the guage changes from empty to full and will stop at any point in between when i stop moving the arm. put it back in the tank and it does not read above the empty mark. it does not matter if the tank is full or 1/2 full of gas when it is checked. the float is also good.

i have spent several hours trying to get the thing to work with no good results. has anyone had a problem like this? if so what was your fix.

can anyone recomend a different company that supplies sending units that might be of better quality. i have had a lot of problems with laysons on other parts that were defective. o far i have only found two other places, but they only list the 3/8 line. if needed then i guess i will change the fuel line from the tank to the carb. thing is i don't want to spend that money if the 3/8 sending units are junk also.

thanks in advance for any input.

Tool Man
Reply With Quote
  #2  
Old 05-27-2003, 12:35 PM
polarapete's Avatar
polarapete polarapete is offline
Inactive User
 
Join Date: Jul 2000
Location: Kirkland, Wa USA
Posts: 266
Default Sending Unit Troubles

I made my own 3/8" unit from a combination of parts and it works fine.

Is it possible that you don't have continuity when it is installed because you are missing the electrical "bridge" that goes from the chassis connected fuel line, jumps the gap that is spanned by the short length of rubber hose and lands at the metal nipple of the sending unit?

I broke the original piece on my Polara and made a replacement of "hair pin clips" and wire. Without this connection, the sending unit when installed properly with the rubber gaskets, is electrically isolated and will not read.
Reply With Quote
  #3  
Old 05-27-2003, 02:36 PM
ehostler's Avatar
ehostler ehostler is offline
Registered User
 
Join Date: Jan 2000
Location: Annandale, VA
Age: 57
Posts: 15,212
Default

I second that opinion...
Reply With Quote
  #4  
Old 05-27-2003, 04:34 PM
dwc43's Avatar
dwc43 dwc43 is offline
Banned
 
Join Date: Sep 2002
Location: Shelbyville,Tn.
Age: 54
Posts: 23,987
Also check the float. Is it heavy or laden with fuel? Does it have a pin hole in it somewhere?
Reply With Quote
  #5  
Old 05-28-2003, 01:19 AM
TOOL MAN's Avatar
TOOL MAN TOOL MAN is offline
Inactive User
 
Join Date: May 1999
Location: GREAT STATE OF MO.
Posts: 161
Default same

thanks,

the ground strap that is from the factory that jumps the rubber hose was replaced and i had the problem still, so i even went as far as running a 10 gauge wire from the frame to the sending unit. the float is empty and it does float. with 8 gal. of gas in the tank i can put the sending unit in and feel the float move.

check this out, a guy at a local repair shop advised me to ground the tank itself anyone know if this is a good idea or a waist of time.

Tool Man
Reply With Quote
  #6  
Old 05-28-2003, 10:22 AM
ehostler's Avatar
ehostler ehostler is offline
Registered User
 
Join Date: Jan 2000
Location: Annandale, VA
Age: 57
Posts: 15,212
Default

grounding the tank is a waste of time. You are already grounding the sender and that is all that needs to be grounded, to work properly.

What you are describing is very odd.

Quote:
with the sending unit out of the tank, using the same indipendant ground and power, i can move the float arm and the guage changes from empty to full and will stop at any point in between when i stop moving the arm. put it back in the tank and it does not read above the empty mark.
Quote:
the ground strap that is from the factory that jumps the rubber hose was replaced and i had the problem still, so i even went as far as running a 10 gauge wire from the frame to the sending unit.
Based on that description, it really sounds as if the float is not floating, however, you are sure that it is.
Reply With Quote
  #7  
Old 05-28-2003, 01:13 PM
TOOL MAN's Avatar
TOOL MAN TOOL MAN is offline
Inactive User
 
Join Date: May 1999
Location: GREAT STATE OF MO.
Posts: 161
Default ????????????

tomorow i am going to place the sending unit in a bucket of gas all hooked up to see if the gas maybe causing the sender not to work. i have also been told that the gas maybe causing the contacts inside the sender to loost contact. if this is the problem then i should be able to take it apart and try to get them to make better contact. if it don't work, well i'm no worse off than i am now.
Reply With Quote
  #8  
Old 05-28-2003, 05:03 PM
ehostler's Avatar
ehostler ehostler is offline
Registered User
 
Join Date: Jan 2000
Location: Annandale, VA
Age: 57
Posts: 15,212
Default

It should just be a rheostat design. The float is connected to a metal wiper that moves across a coil of resistance wire.
Reply With Quote
  #9  
Old 06-01-2003, 11:52 PM
Xterminator Xterminator is offline
Inactive User
 
Join Date: Mar 2003
Location: Fremont, CA
Age: 75
Posts: 171
Default sending unit

Behind your left kick panel is a modular connector that connects the sending unit to the gas guage. Your tail lights and backup lights go through this connector also. With the tank full, you should read approximately 20 ohms between the sending unit and ground. With the tank empty, this reading should be about 80 ohms. Grounding out the wire(zero ohms) that goes to the guage will read way over full on the guage, 20 ohms should read full and 80 ohms should read empty. Check that out, it might indicate what the problem is. Bill E.
Reply With Quote
  #10  
Old 06-03-2003, 07:40 PM
TOOL MAN's Avatar
TOOL MAN TOOL MAN is offline
Inactive User
 
Join Date: May 1999
Location: GREAT STATE OF MO.
Posts: 161
Default fixed

the problem is solved.

there was a problem with the placement of the float and when it was in the tank the float could not get past the boyancy point to float in the right direction. as i have said that i could feal it float inide the tank when i was putting it in, well that was it moving on the wrong side of the swing. adjusted the arm and now it works. sometimes the answer is so obvious that you miss or over look it. so i walked away colected my thoughts, all three of them, and then went back at it with a clear head. found the problem by finding the angle the sending unit sits at in the tank and then placing the sending unit in a bucket of water. the float then moved on the wrong side.

I do thank all of you on this board for all the imput on this problem and others that i have had.

thanks again

Tool Man
Reply With Quote
  #11  
Old 06-03-2003, 09:19 PM
victorian4ever victorian4ever is offline
Inactive User
 
Join Date: Apr 2003
Location: franklin oh
Posts: 52
Default

I wouldn't discount grounding the tank. When ever there is an electrical problem suspect a ground problem first. It will save a lot of time chasing dead ends. I had a sending unit problem on a Lincoln I was working on and I added a ground from the tank to the frame and not only did it fix the gage but also a problem with the dash lights. It seems the gages and light shared a ground under the dash thet just wasn't getting the job done. Try hooking some jumper cables between the pinch weld on the tank and the frame to try it out before going to a lot of owrk
Reply With Quote
  #12  
Old 06-04-2003, 12:58 AM
ehostler's Avatar
ehostler ehostler is offline
Registered User
 
Join Date: Jan 2000
Location: Annandale, VA
Age: 57
Posts: 15,212
Default

AS the fuel sender is electricl isolated from the tank, grounding the tank of is no help. Grounding the sender, as he did, is the perfect choice.
Reply With Quote
  #13  
Old 07-01-2015, 12:58 PM
ram250098 ram250098 is offline
Inactive User
 
Join Date: Aug 2009
Location: Ontario Canada
Posts: 7
Default

I am having the same issue as Toolman, I don't quite understand what he did. I have tried two new senders and a new tank as well as a voltage limiter..everything works outside the tank but does not work when installed..have power have grounds..it seems to be the float issue like TOOLMAN had.
AL
Reply With Quote
  #14  
Old 07-01-2015, 02:44 PM
JVMopar's Avatar
JVMopar JVMopar is offline
Senior Member
 
Join Date: Feb 2000
Location: Mellen, WI
Age: 42
Posts: 2,524
Default

From reading his post, it sounds to me like when you install the sender the arm is in the wrong position and the float is moving the sender in the wrong direction showing a always full condition.

Maybe take it out and mock it up in the same position it would be in the tank and try floating it in a bucket of gas to see what the float is actually doing.
Reply With Quote
  #15  
Old 07-02-2015, 04:14 PM
ram250098 ram250098 is offline
Inactive User
 
Join Date: Aug 2009
Location: Ontario Canada
Posts: 7
Default

Thanks JV..when I tested mine outside the tank I had it working perfect through the full sweep it showed on the gauge..when installed, the float could move up and down just as it should but when it is installed and in the car nothing..I don't get the sender arm being in the wrong position!
AL
Reply With Quote
  #16  
Old 07-04-2015, 07:04 AM
chirorod chirorod is offline
Inactive User
 
Join Date: Nov 2007
Location: Florence, MA
Age: 84
Posts: 724
Default

What is meant by the sender arm in the wrong position is that it is hitting the inside of the tank. That binds it so it can't move. Tank shape is not like a perfect box. And the arm is long so if it's turned the wrong way, it can hit.
Reply With Quote
  #17  
Old 07-08-2015, 04:58 PM
ram250098 ram250098 is offline
Inactive User
 
Join Date: Aug 2009
Location: Ontario Canada
Posts: 7
Default

Thanks. That is what i thought it was..bought a new tank and installed sender and the float moves freely top to bottom.
I even bent the float arm to shorten it up and still nothing.
I don't have enough posts so that I can send Toolman a PM..I am stumped.
Works fine outside the tank just not in it.
Al
Reply With Quote
  #18  
Old 07-08-2015, 09:50 PM
JVMopar's Avatar
JVMopar JVMopar is offline
Senior Member
 
Join Date: Feb 2000
Location: Mellen, WI
Age: 42
Posts: 2,524
Default

With the fuel tank out and empty, can you run jumper wires to the sending unit and move the float arm in the tank throughout it's range?
Reply With Quote
  #19  
Old 07-09-2015, 04:35 PM
ram250098 ram250098 is offline
Inactive User
 
Join Date: Aug 2009
Location: Ontario Canada
Posts: 7
Default

Yes I can which is why is is so puzzling..
Reply With Quote
  #20  
Old 07-10-2015, 09:01 AM
Dick's Avatar
Dick Dick is offline
Registered User
 
Join Date: Oct 2001
Location: Western NH
Age: 80
Posts: 8,880
Default

Toolman hasn't posted here for 10 years.
Reply With Quote
  #21  
Old 07-10-2015, 12:17 PM
ram250098 ram250098 is offline
Inactive User
 
Join Date: Aug 2009
Location: Ontario Canada
Posts: 7
Default

I thought if I pm him it would show up on his email..long shot but you never know!
Reply With Quote
  #22  
Old 07-10-2015, 01:13 PM
Dick's Avatar
Dick Dick is offline
Registered User
 
Join Date: Oct 2001
Location: Western NH
Age: 80
Posts: 8,880
Biggrin

PM's stay on the board and are not linked to email. However, currently active members may chime in the thread with relevant advice.
Reply With Quote
  #23  
Old 07-11-2015, 03:55 PM
ram250098 ram250098 is offline
Inactive User
 
Join Date: Aug 2009
Location: Ontario Canada
Posts: 7
Default

Well got her working...sort of..when tested out of the tank the ohm range was good empty and full. Now in the tank I had about $25.00 in fuel and it read 1/8th tank I put another $43 in and she went to full. ..Ok all is good..but after driving about a half hour it was down to half tank..still not right.
Keep playing the game I guess.
Thanks
AL
Reply With Quote
Reply

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not 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

Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
fuel sending unit problems cudanut jim Vintage MOPAR chat 6 12-08-2016 10:08 AM
1973 Dodge Van temp sending unit and fuel tank float/sending unit. Need info. Mopard Vintage MOPAR chat 7 10-28-2004 09:39 AM
Electrical and fuel sending unit problems Ch@rg3r Restoring your MoPar (Tricks & techniques) 4 09-07-2004 05:57 PM
Fuel tank sending unit/fuel pickup help.. Frank R Restoring your MoPar (Tricks & techniques) 4 08-13-2003 05:06 PM
Fuel Sending Unit 77warlock Performance Talk 7 03-22-2003 10:10 AM




All times are GMT -4. The time now is 04:52 PM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
. . . . .