Fuel Leaking Out Fuel Filler Cap

[Marcus89]

Have been wondering why i was getting very average fuel consumption on my GTT. I knew i was never gonna get fantastic figures but more than what i have was to be expected since it is completely stock and have been driving rather sedately.

Anyway last night i filled up with a little fuel and saw some moisture inside the fuel cap area on the metal lip. Smelt it and was definitely fuel so now i know where at least some of my fuel is disappearing but i have no idea what could cause this issue? Is it a case of getting a new cap?

[mad082]

i'm assuming that you saw this before you took the cap off, etc? if you had been leaking fuel out of there then there should've been some sign of it down the side of the car.

if you are worried about it though, just get a new fuel cap.

and what sort of economy are you calling average? and please don't simply say "i got 300kms to a tank" because "a tank" isn't a unit of measure unless you fill it to the top then drive it till it runs out of fuel. how many kms are you doing for how many litres you put in? also what do you class as sedately? flooring it but only reving it to 3500rpm will still use a fair bit of fuel. how far you push the accelerator down plays a bigger part in fuel economy than what revs you change at. and if you regularly go into positive boost (even at low rpm) then that will increase fuel usage as well.

i was getting about 17L/100kms but i was a bit of a leadfoot and i did a lot of short trips and it was pure city driving, so nothing above 60km/h and never for more than about 1km without having to slow down/stop at an intersection.

other things that can contribute to poor fuel economy is a dodgy o2 sensor or dodgy thermostat. you can tell if the thermostat is dodgy by how long the car takes to come up to operating temp. it should take about 5 mins of driving. if you sit the car and let it idle for ages in the morning before driving it will take longer than 5 mins and also waste a heap of fuel. you can test the o2 sensor with a multimeter

[Marcus89]

My economy definitely isn't as bad as 17l/100km the full tank in the r34's are 65l i think so i would of used 55l for 380kms so 14.5l/100km.

I don't bother idleing the car to get up to operating temperature as i know it's a waste of time and car does get to operating temperature in around 5 mins.

Generally i try to drive off boost altogether and try not too have it planted at low revs as feel this is putting too much strain on the motor.

I do have a fair few short trips although did a fair bit of highway k's this time round thats why i was unimpressed with the figure. I will keep an eye on it try and see if anymore fuel leaks out might try not goin a full tank and see if it still leaks

[mad082]

on the highway, driving mostly sensibly i only got around 10 or 11L/100kms. doing short trips will make your fuel economy worse as the car runs more rich when it's cold, and driving short trips doesn't allow the car to get up to temp and into the leaner running, so you can drive like a granny and still not get as good economy as someone who drives twice as far.