Found an interesting post on here that talks about a problem I've had for years:  Gas gauge only goes up to half full when tank is full.  Half the voices say it's gauge, half say it's sender.  Anybody know for sure?  When I disconnect ground wire, needle goes to top, so it's not stuck.  Getting mechanic to drop tank and install new sender is a big expense, and I'd hate to do that and then find it's the gauge...disassembling that part of the dash and instrument cluster is a huge, difficult project (thanks to windshield in the way) and I'd hate to do that then find it's the sender...

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Morning Lee, 

check this out ,I had the same problem my tank was just filled up and it read half full .did the same thing you did ,disconnected the wire by the fuel door it shot all the way to full. Wasn’t sure if it was the gauge or the sender. I got in the car a few days later turned the key the gauge read half full , so I tapped on the instrument cluster in front of the gas gauge and holy shit ! It moved to the full position. Cleaned the contacts up and put it back together and haven’t had a problem since , glad I didn’t buy a sender or gauge . I guess I got lucky  

That's interesting!  I'll try the tapping idea.  Once started to do the rebuild on cluster but like I say it was incredibly difficult to get access so I stopped.  But would be worth the agony if I knew for a fact that was it.  Bet mine won't respond even if that is the problem, but will try.  Thanks!

Hmm, my sender was completely rusted away. The filter in the bottom of the fuel tank was full with 50+ years of gasoline leftovers.

Dropped the tank (not hard at all when empty). Removed the damaged sender. Cleaned and did the three steps system from Bill Hirsch. Let the tank ventilate for a few days. Installed the new sender. Poured some gas and tried it. It worked but was not showing correct amount on gauge. Drove a few days until tank low on fuel. Dropped the tank and this time followed the manual to the letter. Working excellent since then.

The main issue, apart from a severely rusted sender, was the calibration. Extend the cables so you can work on the tank easily. To get it right the arm on the sender needs to be bent. Just so that when the floater is touching the bottom it moves a fraction on the gauge. It will then follow the fuel to the top and should show full. You might also have to adjust the length of the arm. But the manual is as always excellent.

I did this on my driveway. Dropped the tank on my chest and crawled out with it wiggling on my oversized belly. Sitting beside the tank and re-calibrating a nice spring/summer day is not to hard. Beers tend to be an important tool during this part of the job. Or it might just have been the nice day...

Easiest and cheapest way to sort a problem? Well, for me its easier to get under that car than get into to the dash. I also believe that the environment for a sender is worse than for a gauge. So I tend to aim for the thing that would most likely have had the hardest time. A lifetime at sea has taught me something...

Wow, I respect what it must have taken to do that job.  I'd be afraid of damaging the line lead or never getting the tank properly sealed again.  :)

Russ has done a lot of good things with the calibration of the fuel gauge to get it right 

You might contact him on the subject as he knows it well 

He is a major part supplier on this site 





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