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Old 03-27-2009, 01:56 PM   #159 (permalink)
Deezler
Master EcoModder
 
Join Date: Apr 2008
Location: Michigan
Posts: 261

Bio Deezler (sold) - '03 Volkswagen Jetta GLS TDI
90 day: 50.78 mpg (US)

The Beast. - '03 GMC Sierra 2500HD SLT
90 day: 12.86 mpg (US)
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Quote:
Originally Posted by eyesoreracing View Post
Previous owner drilled a hole in the fuel cap. We picked up a screw off the ground and threaded it into that hole, finger tight, to keep fuel from dribbling down the fender. Still not air-tight, though.

By what mechanism would you expect the results to be off?

-Dave
The side vent tube can fill with fuel foam, or have a varying amount of air in it, at different pressures, thereby adjusting the level of fuel at the bottom of it and thus the total amount in the tank.

Not sure how the rabbit tank is designed, just speculating here. On my car, when you fill to the brim, and then hit the vent tab on the side of the filler neck, the fuel in the neck disappears as the air in the vent tube is allowed to escape. You have to repeat this process severals times to really get the tank full. You can imagine that the amount of air trapped in the vent is highly variable...
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