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Author Topic: Fuel Gauge Not Reading Correctly  (Read 6230 times)

Offline hooD

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Fuel Gauge Not Reading Correctly
« on: July 13, 2010 - 05:48:13 AM »
If the fuel gauge ground strap is poorly grounded will it cause the gauge to misread or not work at all? 

-Larry
member since AUG 2007
http://www.youtube.com/watch?v=NvrWiLgDm7Y

southeastern michigan usa
             
 
            
1973 'CUDA 340
 
original owner
37,009 miles
    
:grinyes: *click my E-Body* :grinyes:

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Fuel Gauge Not Reading Correctly
« on: July 13, 2010 - 05:48:13 AM »



Offline solarguy

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Re: Fuel Gauge Not Reading Correctly
« Reply #1 on: July 13, 2010 - 07:20:38 AM »
sending unit needs a good ground, yes.  The sending unit varies the resistance to ground and that is what the guage is seeing

Offline burdar

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Re: Fuel Gauge Not Reading Correctly
« Reply #2 on: July 13, 2010 - 09:31:55 AM »
Yes, you need a good ground.  Also, those sending units are notorious for not working properly.  Somewhere there is a thread about a fix for this.  I meant to save it but didn't.  It had to do with brazing a wire from the float arm to the main body of the sending unit.  The only place for the float arm to ground is its pivot point where it goes through the body of the unit.  If there is any slop in that pivot point, you won't get a consistent ground. 

Online 06Daytona

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Re: Fuel Gauge Not Reading Correctly
« Reply #3 on: July 13, 2010 - 09:40:05 AM »
I'm going through something along the same lines myself. I get a full reading when I put gas in, but it sputters at half a tank. I'll be checking my ground while I'm troubleshooting the turn signals
1972 Cuda 340 4 barrel 4 speed that looks like a 71
2006 Dodge Charger R/T Daytona
2005 Dodge Ram 2500 Diesel 4X4
2006 Chrysler PT Cruiser Convertible (Kidmobile)
1972 Dodge Charger 318 auto
1970 Challenger 440/727 auto
1973 Plymouth Duster 340/auto (Making it Panther Pink for the wife)
2006 Honda Civic Hybrid (It doesn't save gas, it just diverts it to the Cuda/Challenger)
In desperate need of more property for my growing Mopar family

Offline hooD

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Re: Fuel Gauge Not Reading Correctly
« Reply #4 on: July 15, 2010 - 04:57:29 AM »
The gauge pegs when the fuel gauge wire is grounded.  So I know that the fuel gauge works on the dash and that the wire from the tank to the dash is OK.

I also jumped a separate ground to the sending unit supply tube.  That action did not fix the problem.

So, I figure it is time to replace the sending unit and be done with it.

And it looks like I may be able to change the sending unit without dropping the tank.  I will have to remove the exhaust heat shield on the driver's side, but with that out of the way it looks like I will have the clearance to do this.  I'm keeping my fingers crossed.

-----------------------------------------------
Autozone has them.  Anyone tried these?

Spectra Premium/Fuel Tank Sending Unit
For your 1973 Plymouth Barracuda 5.6L 4BL 8cyl

Price:  $75.99

Part Number:    FG67B
Weight:    1.5 lbs
Warranty:    1 YR
Application:    Cuda model
Notes:    3/8" outlet Includes fuel sender, float and strainer (fuel pump not included). With return line
Number of Outlets:    2
Includes:    Strainers, lock ring and o-ring
Description:    Includes fuel sender, float and strainer (fuel pump not included)


-Larry
member since AUG 2007
http://www.youtube.com/watch?v=NvrWiLgDm7Y

southeastern michigan usa
             
 
            
1973 'CUDA 340
 
original owner
37,009 miles
    
:grinyes: *click my E-Body* :grinyes:

Offline Katfish

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Re: Fuel Gauge Not Reading Correctly
« Reply #5 on: July 15, 2010 - 06:54:38 AM »
You can definitely do it without dropping tank.  I just did mine.

Take yours apart before you by a new 1.  I was able to fix mine.  The brass contact had corroded away and fell off the pivot arm.  I was able to clean it up and solder it back on, working good as new now.

Offline hooD

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Re: Fuel Gauge Not Reading Correctly
« Reply #6 on: July 15, 2010 - 12:28:30 PM »
You can definitely do it without dropping tank.  I just did mine.

Take yours apart before you by a new 1.  I was able to fix mine.  The brass contact had corroded away and fell off the pivot arm.  I was able to clean it up and solder it back on, working good as new now.

excellent information, just what I needed to hear.  thanks!
-Larry
member since AUG 2007
http://www.youtube.com/watch?v=NvrWiLgDm7Y

southeastern michigan usa
             
 
            
1973 'CUDA 340
 
original owner
37,009 miles
    
:grinyes: *click my E-Body* :grinyes:

Offline solarguy

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Re: Fuel Gauge Not Reading Correctly
« Reply #7 on: July 15, 2010 - 04:49:40 PM »
You didn't really say, but if it's reading "empty" all the time, the sending unit itself could still be good and the problem could be the "float".  I've had a couple of the original brass type floats get minute holes or cracks in them and then they of course fill up with gas.  At this point they aren't "floats" anymore and you could call them "anchors".
 


 :iagree:  I just changed my float about 3 months ago and the old one is sitll on my bench and still 1/2 full of gas.  needle would stay at empty or drift around if I drove in a manner that caused gas in the tank to swoosh around. 

Offline hooD

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Re: Fuel Gauge Not Reading Correctly
« Reply #8 on: July 16, 2010 - 04:19:33 AM »
You didn't really say, but if it's reading "empty" all the time, the sending unit itself could still be good and the problem could be the "float".  I've had a couple of the original brass type floats get minute holes or cracks in them and then they of course fill up with gas.  At this point they aren't "floats" anymore and you could call them "anchors".

 :iagree:  with Katfish, better to repair the original if possible than to buy a reproduction that may or may not work properly either.

The gauge has been varying with the readings.  It is not always sitting on "E". 

After I was fooling around with the ground strap the gauge registered even less than it did before.  I have a full tank and it was on then it dipped to a hair above "E".   This is with the car parked.

I'm all for repairing the original if it is repairable.  Any detailed info on the repair would be appreciated.



 
« Last Edit: July 16, 2010 - 04:21:23 AM by hooD »
-Larry
member since AUG 2007
http://www.youtube.com/watch?v=NvrWiLgDm7Y

southeastern michigan usa
             
 
            
1973 'CUDA 340
 
original owner
37,009 miles
    
:grinyes: *click my E-Body* :grinyes:

Offline Katfish

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Re: Fuel Gauge Not Reading Correctly
« Reply #9 on: July 16, 2010 - 04:45:57 PM »
Sounds like you have a sunk float.  Easy fix, pull the sender from the tank.  Remove float from swing arm.  Shake it, if you hear/feel gas inside, you've found the problem.

Offline pink panther

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Re: Fuel Gauge Not Reading Correctly
« Reply #10 on: July 16, 2010 - 05:28:04 PM »
If you need a new one, go through Dave at Roseville mopar, great guy to deal with
Scott   -  Member since 9/18/2005

Offline hooD

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Re: Fuel Gauge Not Reading Correctly
« Reply #11 on: July 17, 2010 - 11:23:02 PM »
So, today I go out for a cruise and the fuel gauge is reading on E.  The next time I look at the gauge it comes up to a quarter tank.  I stopped at my son's house for an hour or so and I when I start the car up I have a very true reading which is now at 3/4 of a tank.  At this point I'm not going to do anything with the sending unit.  I'm going to see what it continues to do.  I will update this if things change.

-Larry
member since AUG 2007
http://www.youtube.com/watch?v=NvrWiLgDm7Y

southeastern michigan usa
             
 
            
1973 'CUDA 340
 
original owner
37,009 miles
    
:grinyes: *click my E-Body* :grinyes:

Offline hooD

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Re: Fuel Gauge Not Reading Correctly
« Reply #12 on: July 23, 2010 - 04:19:36 AM »
The cuda has been sitting in the garage unused since last weekend and the gauge read tank.  I checked the fuel gauge yesterday and it reads tank.  I will be yanking the sending unit out before the end of summer. 
-Larry
member since AUG 2007
http://www.youtube.com/watch?v=NvrWiLgDm7Y

southeastern michigan usa
             
 
            
1973 'CUDA 340
 
original owner
37,009 miles
    
:grinyes: *click my E-Body* :grinyes:

Offline shadango

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Re: Fuel Gauge Not Reading Correctly
« Reply #13 on: July 23, 2010 - 07:18:41 AM »

 :iagree:  with Katfish, better to repair the original if possible than to buy a reproduction that may or may not work properly either.

 :iagree:

Ask me how I know this.  LOL

I am contemplating the trick someone posted about soldering a wire from the float arm to the body of the sending unit and seeing if that helps.

Offline brads70

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Re: Fuel Gauge Not Reading Correctly
« Reply #14 on: July 23, 2010 - 11:04:25 AM »
 :pullinghair: Mine was reading full all the time? I just ordered a new sending unit kit from Dave at Roseville. ENOUGH already!  :bigsmile:
Brad
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Re: Fuel Gauge Not Reading Correctly
« Reply #14 on: July 23, 2010 - 11:04:25 AM »