[Shotimes] Re: gas gauge off by 1/4 tank

[MonsieurBoo@aol.com]

"It is pessimistic (reads lower than actual fuel on board) by about a quarter 
of a tank."

Once upon a time I'd say check for poor connections that would increase the 
baseline impedance.  But me not having a SHO manual, in about two seconds 
someone will write and say you idiot, it's a voltage signal!  Well, here's one that 
will always work.  Carefully detach the needle and super glue it back on 
1/4-tank clockwise.

OK then, let me take a brief offcourse excursion that might be interesting.  
I'm helping our local gas station owner computerize his business.  He has an 
automatic tank gauge in each tank that takes readings every day and he's had to 
calculate the variances manually and file EPA reports if the differences 
between the readings and his gallonage sales are more than +/- 2%.  As soon as I 
started graphing it I noticed big down/up spikes in the curves just like an 
EKG.  When I correlated them with fuel deliveries it was clear that the tank 
readings are excessively low when the fuel level is low, and conversely the 
readings are excessively high when the level is high.  This is because, as I 
suspected and we found out, the response curve of the gauge transducer hasn't been 
linearized.

We're having a bit of a field day with this because the EPA was hassling them 
about the "missing" gas.  (Some days it looked like the tanks had leaks, 
other days inexplicably there seemed to be extra gas, but they were focused on the 
shortages.)    Apparently there's no way to flatten the transducer curve 
either.  Rather amusing actually.

Mark LaBarre
Rockville, MD
'94 green 125K