Fuel consumption issues

[jampo]

My 91 VN wagon gets really terrible fuel economy: in the city around 320kms, and 450 on the hwy.
There is another wierd thing too: if the fuel indicator is sitting below a quarter of a tank and I have it parked on a street that slopes sharply towards the gutter it won't start 'till I stick another 10L in the tank....
The gauge sits on around 3 qurters full for the first 250km then plummets to a quarter... this has left me pissed off a few times when the guage seemed fine when I parked it, but when I get back in it has dropped a quarter of a tank...

Anybody got any idea why and what I can do to fix it?

 

[ViperVp]

i can't help you with the fuel guage but as for the kms, here is a few post that talk about fuel + Kms
http://forums.justcommodores.com.au/showthread.php?t=5359
http://forums.justcommodores.com.au/showthread.php?t=6636

 

[rattattack1313]

gazzz tank...

hey bloke........ I think you will find that the petrol pump can't pick up the fuel in the tank when it's on an angle,when there is little fuel in it,is because the pump etc is on the right hand side of the tank.... and when it is parked on an angle, the fuel isn't reaching as high up as the pickup... :b:

 

[MavVP]

you also might want to try checking your fuel sender, that may be the reason for your incorrect fuel guage

 

[greenfoam]

I just drove 165kms on 13 liters of fuel and still had plenty spare so I can't wait to test it properly with a full tank, drive then re fill to see what it's exactly but I hope to be consistantly under 9l per 100k in my auto on the highway (now running about 17.5:1). I think if your MAP sensor AND the O2 sensor are working properly then you must get about 9-10L per 100k at the stock closed loop 14.7:1 fuel ratio because those are really the main two things that could stuff it up. Now that I thought about it some more I don't think the MAP sensor would be a big problem because the O2 sensor should be able to compensate anyway I think :/