Robby120113 Posted September 25, 2020 Share Posted September 25, 2020 Goodmorning, my fuel gauge is working only for the last quarter. That the most important part luckily. But how can i get the full range again. thanks for the tips Link to comment Share on other sites More sharing options...
rodneybeauchamp Posted September 25, 2020 Share Posted September 25, 2020 On my ‘38 I found the spiral resistor wiring had failed so the gauge was giving false readings and flicking violently at a certain level. After removing the gauge, was able to make one out of two from a ‘37 unit and now have a reliable gauge back in there. Cleaned the tank out at the same time, so double bonus. You may be able to repair the old one with some care or locate a second hand unit off the forum. good luck Rodney 😀😀😀😀😀😀😀 Link to comment Share on other sites More sharing options...
37_Roadmaster_C Posted September 26, 2020 Share Posted September 26, 2020 Please give us a more detailed description of the failure. For example: the gauge reads correctly when the tank is between 1/4 and empty. When over 1/4 full the gauge reads xxxx (full or empty). 1930's GM gauges read full when the tank sender wire is open and empty when the tank sender wire is shorted to ground. A full description will tell us what is happening electrically. Link to comment Share on other sites More sharing options...
Matt Harwood Posted September 26, 2020 Share Posted September 26, 2020 Sounds like a sending unit problem simply because it works correctly from 1/4 to Empty. The resistor is failing or the float arm is damaged somehow. I don't know for certain but I believe the sending unit is the same as the '41, and they're commonly available. The Buick suppliers sell them for $75 but Summit Racing sells the exact same one for about $35 (https://www.summitracing.com/parts/tnk-b1-s). I'll wager that's your problem. 1 Link to comment Share on other sites More sharing options...
Robby120113 Posted September 26, 2020 Author Share Posted September 26, 2020 It is indeed not going further up then 1/4. To replace the fuel sender does the fueltank have to be removed? thanks for the tips Link to comment Share on other sites More sharing options...
neil morse Posted September 26, 2020 Share Posted September 26, 2020 1 hour ago, Robby120113 said: It is indeed not going further up then 1/4. To replace the fuel sender does the fueltank have to be removed? thanks for the tips Yes, you have to remove the tank to replace the sender. Here's how I did it on my '41. Not too difficult. (Click on arrow in upper right hand corner.) Link to comment Share on other sites More sharing options...
kgreen Posted September 27, 2020 Share Posted September 27, 2020 Yup, If Matt hadn't noticed your post I would have directed you to a thread of his with a discussion of his replacement. Link to comment Share on other sites More sharing options...
neil morse Posted September 27, 2020 Share Posted September 27, 2020 14 minutes ago, kgreen said: Yup, If Matt hadn't noticed your post I would have directed you to a thread of his *with a discussion of his replacement.* Matt is irreplaceable as far as I'm concerned. 😄 1 Link to comment Share on other sites More sharing options...
Morgan Wright Posted September 27, 2020 Share Posted September 27, 2020 The sending unit is has a cork float. If it works part of the time something might be wrong with the cork. You can get a new cork from a bottle of wine. Very easy, but you need to remove the tank to get to it. That's what the wine is for. 3 Link to comment Share on other sites More sharing options...
Bloo Posted September 27, 2020 Share Posted September 27, 2020 If it's cork, and you use the one from the wine, don't forget to seal it first. Gas tank sealer might work. Bob's has pre-sealed corks as an alternative. 1937 Buick still used a cork. Did 1940? Link to comment Share on other sites More sharing options...
Morgan Wright Posted September 27, 2020 Share Posted September 27, 2020 37 minutes ago, Bloo said: If it's cork, and you use the one from the wine, don't forget to seal it first. Gas tank sealer might work. Bob's has pre-sealed corks as an alternative. 1937 Buick still used a cork. Did 1940? Yes I had a 1940 once 1 Link to comment Share on other sites More sharing options...
neil morse Posted September 27, 2020 Share Posted September 27, 2020 The original sending unit on my '41 used cork. Link to comment Share on other sites More sharing options...
Robby120113 Posted September 27, 2020 Author Share Posted September 27, 2020 Then i have to make time and motivation to take the fuel tank out. Thanks all Link to comment Share on other sites More sharing options...
Morgan Wright Posted September 27, 2020 Share Posted September 27, 2020 1 hour ago, Robby120113 said: Then i have to make time and motivation to take the fuel tank out. Thanks all The only thing holding the tank in is 2 steel straps. One or two nuts on each strap and it falls out, especially with help from the weight of 15 or 20 gallons of gas. Only kidding. Empty the tank first. 1 Link to comment Share on other sites More sharing options...
Bloo Posted September 28, 2020 Share Posted September 28, 2020 You'll need 2 corks....... Link to comment Share on other sites More sharing options...
Morgan Wright Posted September 28, 2020 Share Posted September 28, 2020 4 hours ago, Bloo said: You'll need 2 corks....... ?? Link to comment Share on other sites More sharing options...
2carb40 Posted September 28, 2020 Share Posted September 28, 2020 (edited) 13 hours ago, Robby120113 said: Then i have to make time and motivation to take the fuel tank out. Thanks all On my 1940 Super coupe there was an interesting circular pattern stamped in the trunk floor right above the circle of bolts needing to be removed to take the sending unit out of the tank. Used a hole saw to remove trunk metal and made a circular access panel for servicing sender and wire when and if needed, rather than having to deal with weight and bulk of tank removal. Covered with trunk matt. Adjust centering drill bit on hole saw to just barely enuff sticking out. Hole in trunk metal yes, hole in top of tank, no! Good luck! Run drill in reverse when using holesaw in sheet metal. Edited September 28, 2020 by 2carb40 (see edit history) Link to comment Share on other sites More sharing options...
Morgan Wright Posted September 28, 2020 Share Posted September 28, 2020 Taking the tank out is real easy. Simple job. Link to comment Share on other sites More sharing options...
neil morse Posted September 28, 2020 Share Posted September 28, 2020 8 hours ago, Morgan Wright said: ?? I think this is what Bloo meant when he said you'll need two corks. This is the original sending unit from my '41. 1 Link to comment Share on other sites More sharing options...
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