Fuel Consumption: Cessna Indicator Vs. Shadin

[Jose L. Ichaso]

Does any one`s 337 equipped with a Shadin fuel computer has diferent indications at the fuel comp. and the Cessna indicator. The avionics shop says is because it takes it`s reading from diferent places ( before and after the fuel injection unit). For exmple I have record this readings:


GPH

Cessna Ind. Shadin
6500' 22" 2400rpm 8 & 10 11.2 & 11.0

(other day flying)
7500' 21" 2400rpm 9 & 10 10.9 & 10.9


When refilling the tanks the shadin math it by 3 or four gallons. If I wouldn't have the computer, howcome can you trust this indication?
By the way,I had send this instrument to the shop to have a check and calibration with the same results.