1990 z32 bad gas mileage, and fume smell in cabin
 

I did a twin turbo swap into an na chassis for a customer. The car runs great, but the customer is only getting about 130 miles to a full tank, and there is a slight smell of gas fumes in the car. I was thinking its either the 02 sensor or the MAF sensor?!? Does that sound about right, has anybody else had this problem???

Did you bother to check for a fuel leak?

Yeah i checked all the lines in the engine bay no leaks, and i checked the fuel pump and there was nothing. I still havent gotten underneath the car tho.

i had a similar issue with my n/a it was running really rich and crappy from bad injector....

Ohm out the injector, the old style really are bad about going out now the ethanol....
If one or more are bad don't just replace it because nearly all fail shortly after the first.
Best price injectors are JECS, Nissan OEM ,, they come in many sizes and NEW not rebuilt ..

z's are prone to fel leaks during weather changes. one way i kept track of mine was to put a thing layer of baby powder on the motor early morning before you start it(or any cold start, thats when all my leaks occured), anywhere you have a leak the powder will disolve...otherwise smelling around for a gas is hit or miss.

otherwise, towards the front of the plenum, where the throttlecable lever is, is two fuel lines that connect via plastic hose, theres a little screw there, tats where mine would always leak from.

Could be the O2 sensors as well....when the same thing happened to me though it was just a leak by the fuel filter