Join Date: Nov 2009
Location: Lander, Wyoming
Sportinh2o, Test its fuel flow / air flow. With open cap & closed cap.
Get yourself an empty 5 + gallon fuel can/jug/bucket. Connect 1/4" fuel hose to fuel tap. If automatic vacuum fuel valve, connect a 3/16" vacuum hose, squeeze a Visine bottle near flat & connect to vacuum hose. That tiny amount of continuous vacuum is all that is needed to open the fuel valve.
The fuel needs to flow at a rate of at least 3 gallon per hour or 6.4 ounces per minute or better for the full tank. That would more than feed the worst fuel mileage (35mpg) I've ever gotten in a head wind at full throttle.
Could measure it on a cool night & a Hot Sunny day. It is pretty common to hear those fuel cap vents 'sing' or maybe its 'whimper' to us on a hot day.