You're runnin' out a gas, ya' big dummy!...
Seriously,... a typical petcock problem is cured by blocking off the vac line and running on Prime... or a vac line leak, by just running on prime...
Going to reserve,... could mean that your On postion fuel tap is clogged and needs cleaning, or...
You're runnin' out a gas, ya' big dummy!...
I only say that, 'cause you're too far away to smack me...
BTW,... a Raptor petcock is about $20 + $10 shipping... very sexy for a metal thing...