View single post by Tom Bradley
 Posted: 04-30-2014 05:51 am
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Tom Bradley

 

Joined: 07-15-2013
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(thought I would put my experience here in case it is of help to anyone else)

In getting my JH back running after sitting for several years I had a problem with the gas gauge reading empty even with fuel in the tank.  I tracked this down to the sending unit reading infinite resistance.  Since the insides of the unit are a potentiometer, I decided to try an old electronic technician trick to get it working: WD-40.  What I did was spray WD-40 into the joint where the float arm goes into the sending unit (see pic), then gently moved the float arm back and forth from the full to empty stops.  I had to do this several times before I started to see any electrical conduction at all.  It took about a dozen repeats over several days (leaving time for the WD-40 to work) before I got really consistent behavior with no open circuit conditions anywhere between the stops.  Now it is reading 240 ohms empty and 20 when full, which is about right from what I have read elsewhere here.  (When checking the resistance, have the unit upright, the way it is in the tank--when it is lying down the electrical contact was not as reliable with mine).  It is back in the tank and seems to doing OK so far.  My guess is that any light weight anti-rust oil in a spray can, like Kroil or Liquid Wrench will probably work as well, but WD-40 is the only type I have experience with.  If this does not work, opening up the sending unit container and spraying contact cleaner directly on the contact area might work, but sending it to someone experienced, like DMS might be better.  Unless you are an experienced electronic tech, I would not recommend using any sort of physical contact to try to clean it up.

Attachment: gas guage fix.JPG (Downloaded 170 times)