kvc@scgvaxd.UUCP (Kevin Carosso) (10/26/84)
Here's a problem that seems all too common that I hope someone has an answer for... My '79 RX-7 has a really annoying problem with the fuel gauge. The damn thing reads F when I fill the car up. Then, the speed at which the needle moves seems to change as the fuel level changes. It starts out moving very fast, and gradually slows as the level gets lower. This means that the tank is about 3/4 (or more) full when the needle reads 1/2, about 1/2 full at 1/3, etc... Unfortunately, this means the needle moves very little down at the bottom of the gauge and makes it impossible to get any idea just how much gas there really is in the tank. I sort of get around it by knowing about how many miles I have to a tankfull, but I almost got bit when I didn't get the tank all the way full at the last stop for gas, and didn't have as many miles as I thought I did! Anyway, has anyone else every had a car do this? Anyone know an easy way to fix it? I had a Jag for awhile that was logarithmic the other way, needle got REAL sensitive down at the bottom of the tank. That was nicer, since you did know when you had to fill up (far too often in the Jag), but I'd still rather have a linear indicator. Thanks for any help... /Kevin Carosso scgvaxd!engvax!kvc Hughes Aircraft Co.
pwv@fluke.UUCP (11/01/84)
Find your fuel tank and take a look at it. Every vehicle I have seen that
exhibited the sort of problem that you describe (non-linear fuel gauge) had an
irregular shaped fuel tank to allow clearance for spare tires, suspension
parts, body contouring, etc. It's not that your gauge is "logarithmic", in
fact, it's probably quite linear. The reason behind it all is that the fuel
level drops non-linearly.--
Pat Vilbrandt
John Fluke Mfg. Co., Inc.
Everett, Washington USA
{ uw-beaver, decvax!microsoft, ucbvax!lbl-csam, allegra, ssc-vax }!fluke!pwvjackh@zehntel.UUCP (jack hagerty) (11/06/84)
> My '79 RX-7 has a really annoying problem with the fuel gauge. > The damn thing reads F when I fill the car up. Then, the speed > at which the needle moves seems to change as the fuel level > changes. > ...this means the needle moves very little > down at the bottom of the gauge and makes it impossible to get > any idea just how much gas there really is in the tank. It's just possible that the Nichrome wire on the tank sender is wound backwards. These are usually wound logarithmically with the sparse end near full (so that a relatively large movement of the float is required for a certian resistance change) and the dense end near empty (for large resistance changes with float movement). If this were installed backwards it would have the characteristics you describe. Jack Hagerty, Zehntle Inc. ...!ihnp4!zehntel!jackh