Hi Robert,

We have a fuel cap tester which is used in certain state emission inspection programs. However our tester does not test with vacuum, rather pressure. For more information please use the links below...

http://www.hickokwaekon.com/automotive-diagnostic-tools/emissions-testing/fpt2600e-fuel-cap-pressure-test-system.aspx

http://www.hickokwaekon.com/automotive-diagnostic-tools/emissions-testing/fpt25-16-fuel-cap-pressure-test-adapter-kit.aspx

Tj Bauaman
Manager/Marketing Representative
Hickok Waekon
Cleveland, Ohio, USA