Alrite ppl, wonder if u can help me out here. (sorry for the long post). My car is a 1.2 8v corsa (but its the same principle for most of the early 90's vaux's i think!)
Basically i thought my car was suffering badly from high fuel consumption, as it seemed to be givin me bout 15-20mpg round town, which as u no, is quite crap for a 1.2 - (meana be bout 25-30+). This was recorded by fillin up tank, doin 100 miles and fillin it back up etc to c how much i had used.
However, after closer examination, the fuel consumption/usage is fine! During a round town drive, the guage hardly moves at all - ie: when i come back from a 20 mile urban trip, the guage has hardly shifted from the position it was in when i departed.
However, when i leave the car overnight, then i restart the engine in the morn, it seems i've lost fuel!!! The guage never returns to place i left it the night before!! Usually bout 3-5 indicated litres less!!! The longer i leave the car, the more fuel i seem to lose. ie: leave it 20 mins and the guage returns to same place, so i dont think it's the guage at all.
I realise that the corsa uses an emissions system, where by evaporated fuel gets stored in a carbon canister, then on restart, sucked back into my inlet manifold. Ever since i've had the car, the fuel tank vent valve has been broken so i'm thinkin, could it be possible that my fuel is evaporating over night, and leaving via the fuel tank vent valve?????? (fitting new one 2moz)
I mean 2+ litres is a very excessive amount to evaporate over night, but i cant think of anything else. I mean, the zaust runs under the petrol tank, so could the heat be causing evaporation to occur?
I've checked for leaks, and there are none. There is also no smell of petrol out or inside the car, or under the bonnet! Oh, and i have a locking fuel cap, so NO, fuel is definately not being syphoned out! And one more thing, i only ever check the fuel guage on my driveway at home to ensure its a fair test each time!!
Any ideas would be appreciated!!! I mean, its costing me loads
thanks alot in advance