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  #16  
Old 02-06-2011, 03:21 PM
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Join Date: May 2010
Posts: 64
fuel guage flickering rectification.

Hi y'all i fixed mine by removing sending unit,carfully slip locking ring down unit tube.pull sending unit tube apart carefully thus not damaging the very fine conductor wires exposed and thereby exposing float and both conductor wires.carefully clean them by using mild abrasive cleaner between thumb and forefinger.you can also clean the tube by using same abrasive cleaner on the inner barrel which also prevents the float from sticking.reinstall parts in the reverse and install sender in tank.reconnect the plug and check your fuel guage,it should be reading steady.thats my fix.Happy cruising Y'all.

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  #17  
Old 01-11-2019, 11:04 AM
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Join Date: Sep 2017
Location: Arkansas
Posts: 1
1986 w124 erratic fuel gauge needle

The answer is here;
http://www.peachparts.com/shopforum/tech-help/17073-bouncing-fuel-gauge.html

This seems to be a problem with w124 and some other models. My fuel needle would start to jump when the fuel gauge was less than half full and didn't go away until I added fuel above half tank. I fixed the problem and did not touch the fuel tank or the fuel gauge. I started with the simplest solution. I didn't believe it at first but 'Marvel mystery oil' fixed my 1986 300E erratic fuel gauge needle last year. Just add 4oz per 10 gallons of fuel. I used one bottle, in about 2 months the problem went away and hasn't returned. I am not associated with the company, this stuff works. Thanks to 'rurindum' for posting his experience.
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  #18  
Old 01-11-2019, 01:52 PM
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Join Date: Nov 2010
Location: TX
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Quote:
Originally Posted by JD300e View Post
The answer is here;
http://www.peachparts.com/shopforum/tech-help/17073-bouncing-fuel-gauge.html

This seems to be a problem with w124 and some other models. My fuel needle would start to jump when the fuel gauge was less than half full and didn't go away until I added fuel above half tank. I fixed the problem and did not touch the fuel tank or the fuel gauge. I started with the simplest solution. I didn't believe it at first but 'Marvel mystery oil' fixed my 1986 300E erratic fuel gauge needle last year. Just add 4oz per 10 gallons of fuel. I used one bottle, in about 2 months the problem went away and hasn't returned. I am not associated with the company, this stuff works. Thanks to 'rurindum' for posting his experience.
What you did was clean the wire inside the sending unit, Its a very common problem. And your solution is the "standard" first attempt to fixing it. - which usually works too
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  #19  
Old 01-13-2019, 09:30 AM
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Join Date: Mar 2003
Location: Southern California
Posts: 2,272
I first experienced this problem about 10-15 years ago on my 201 when the fuel gage got down to about 3/8 and below. Based on having the same issue on my Cosworth Vega I assumed that deposits had built up on the potentiometer. Since I'm in the habit of filling the tank when it gets down to about 3/8 the wiper rarely passes along the wire below this level allowing deposits to build up, creating high resistance and/or moments of discontinuity.

Rather than remove and clean the sender as I did on the Cosworth Vega, I decided to do an "in-place cleaning".

I had a 450 mile Thanksgiving trip planned to northern CA to visit friends, so I left with about 3/8 of a tank and mapped out several fuel stops corresponding to about when it hit reserve. I bought a bottle of Chevron Techron and added a few ounces before I left and a few ounces at each stop where I added about three to four gallons of fuel. I also made most of the trip on two lane roads in the coastal mountains and Sierra Nevadas - lots of twisty roads so the fuel sloshed around as much as possible to move the float up and down.

That fixed the problem for a long time, but I've noticed in the last year or so that it's returned occasionally, so it's time to do the Techron treatment, again.

Duke

Last edited by Duke2.6; 01-13-2019 at 09:42 AM.
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  #20  
Old 01-13-2019, 04:09 PM
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Join Date: Dec 2006
Posts: 3,941
There are two and only two possible causes for this problem:

1) The fuel gauge sender is dirty. Having tried every possible type of chemical fix, the only permanent solution to this is to take the sender apart, carefully wipe off the resistance wire, and reassemble. This problem is much more likely in a Diesel car. (BTW, the base chemical in MMO is Stoddard's solvent, AKA paint thinner.)

2) The fuel gauge damper coil has a broken spindle. If you pull your dash pod and examine the innards of the fuel gauge, you will find that there's a choke coil wrapped around a plastic spindle. This is what gives "slowness" into the reaction time of the gauge. If a physical shock, like driving through a pothole, has broken the spindle, the coil can intermittently ground against the steel case of the gauge and cause the needle to blip. The solution is to simply use some electrical tape to isolate the coil from the gauge.





You can usually tell the difference between these two conditions: the first will tend to occur at a particular fuel level, the second can occur randomly regardless of level.

Last edited by Mxfrank; 01-13-2019 at 04:24 PM.
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  #21  
Old 05-18-2023, 01:02 PM
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Join Date: Dec 2000
Location: Bridgetown, Nova Scotia
Posts: 574
I have a brand new one and it does the same
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  #22  
Old 05-21-2023, 04:13 PM
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Join Date: May 2023
Posts: 10
You can actually just clean the existing sending unit (the string) with an SOS pad. That's what I did and mine is as good as new.


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  #23  
Old 05-21-2023, 08:12 PM
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Posts: 2,761
Be VERY gentle when cleaning the strings they are fragile.

Good luck!!!

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