Huge fuel consumption on VN

[cev]

Hi there, I know this is covered a bit down but needed some more assistance than that.

My VN which now has 310,000kms has been wasting fuel way 2 much. I hardly drive it now but when I do it guzzles, badly. When its above halfway it aint too bad, but once its gets to about halfway, the thing rockets down like anything.

My filters are all clean, I service it myself every 7-8000ks, changing all the filters (air, oil, fuel). I tried spraying about a quarter can of carby cleaner in the throttle body but aint noticed anything drastic.

Do I need to use more carby cleaner? I heard too much aint safe?

I am changing my leads probably this week to see if this helps too.

Have used injector cleaner on my last two pours, still nothing.

Car is usually hard to start and wastes too much fuel.

I know the injectors need cleaning but I dont wanna fork out for that now.

What is a O2 sensor worth? Actually what is it exactly, im not too cluey on what it is.

Thanks.

 

[Ultima RB]

Are you sure it's not just you guage playing up? If you could work out your fuel consumption it may help finding the problem. For example fill it right up and reset your odometer. Drive till it's nearly empty then fill it up again. You can then work out how many kilometres you've done on how many litres of fuel.

The oxygen senser measures the amount of oxygen in the exhaust gases which are flowing out of your engine and through your exhaust. Looking in your engine bay it should be located on the right exhaust manifold with a black wire connecting it up to the computer.
The o2 sensor can be faulty and give incorrect reading such as a lean reading which would tell the computer the car is running lean. The computer would then tell the injectors to pump more fuel in till the o2 sensor gave a correct reading.

It is possible that there are cracks in your exhaust manifold, this would enable oxygen to get into your exhaust before the sensor and give the incorrect lean reading. (This happened to me, was getting 20L/100km)