There's a hissing noise from under the car when I push the throttle. I'm getting terrible gas mileage. I smell fuel. Help.

 

here is a start
if you would really like answers that would help you and avoid flames give the following info when you post: year of car, n/a or turbo engine, stick or slushbox, digital or analog dash. Most of us can tell by the year what model you have ie 85T is a turbo z31. Z cars come in many flavors and they are all different. example 84,85,86 Z31's pretty comparable. there were changes in 87,88,89. in addition 300ZX can refer to two completly different cars the Z31 and the Z32. No mindreaders here the more info you can post the more likely you get a cogent useful answer. The cars with L engine (straight six) changed almost yearly from their introduction. A 240Z and and a 280Z have similarities but they can also have wide variance.

 

Ah good point my bad. It's a 1991 Z32 NA slick top 5 speed analog dash( is that redundant/aren't all z32 analog???). stock though I don't know much else as far as models and engine types.