"John Heath" <johnheath@usinternet.com> wrote: >91 Audi 200TQ 66K miles. Full tank of gas starts right up. Half tank or >less 5 second crank time then it slowly catches. If you take the fuel filler cap off when the tank's half empty, do you hear it hiss? If so, the cap's ventilation is blocked, and it's drawing a vacuum inside the tank. BTDT with the wrong cap on my old Jetta. Tom