My experience = on poor engine performance caused high fuel consumption was about the = ignition cables. This idle rpm was ok but not so smooth and got the = black smoke when pressing acceleration pedal down. I changed all of = ignition cables(coil to distributor and distributor to spark plugs) and = finally obtained pretty good consumption rate.

Before leak = test on fuel tank or change something, try checking the fuel gas cap = first.

Hope this may = help,

Chayan = Srisawat
'89 Syncro and = '72 Bus
Rayong, = Thailand