Fuel consumption/tank size

[samueljm]

Hi All,

I recently bought a 93 VR wagon executive, auto, 3.8. It's sitting outside my place, not starting , and it sounds like it's run out of fuel as I can hear the pump. Now, it's done exactly 405km since last full fill, which, if my calculations are correct (no guarantee!), puts its consumption at around 16.9/100km, if the tank is 68L. This seems awful high, even for city driving (which it is). Apparently it is supposed to do 10-13L/100km, or give me at least 520km from a full tank. Anyway, I was expecting to get at least another 100km out of the tank, which explains how I got caught out without fuel.

The fuel gauge is working, but seems to go very quickly from 1/4 full to empty very quickly compared to fuller stages.

(No fuel on the ground).

Now, I've been a pretty conservative driver, as I wanted to see how much I could get out of a tank. No excessive revving or accelerating.

Does anyone know why it seems so inefficient? Or is this normal? Or does anyone know if the fuel tank is actually quite a bit smaller? The numbers would make more sense if it has a 50L tank... Could it have been changed (wagon has been lowered, and has replaced exhaust)? Any ideas?

A hearty thanks for any advice.

[-=ApheX=-]

you can't really take good measurements on fuel usage for the simple fact that there are alot of contributing factors involved. e.g. How you drive it, weight your pulling in and out of the car, how well it's been kept serviced, if it's out of tune, etc.
What I would suggest is if your keen to get far better fuel econamy then a few simple things need to be followed.
A Major service; Plugs, leads, filters, oil, coolant etc.
A deeper search; Fuel filter, injectors, clogged throttlebody, stuffed O2 sensor etc.
do an error code check
Then fix errors,
If all is good then proceed with eliminating possible causes of excessive fuel use.
Once you've done as much as you can take it to a well established mechanic for an opinion only, then get a second opinion. Then decide to get a major service.
That's what I would do.
Good luck

[AussieHuddo]

sounds about normal for city driving...especially in a major city. the v6s get great fuel economy on the road tho like mine got 7.9L/100km to melbourne and back.

also mine drops from 1/4 to empty faster than fuller stages but thats just the cars own personality...you just gotta learn to live with it

[wildeagle44]

68L tank sounds about right, but 16.9/100km sounds high so it may need a major service. How many k's on the odo?

[Hams]

i have to say that i have the same problem, i own a vs 5 speed and im getting around 300-350km's out of a full tank.
it was an auto but was swapped over, i found out that i was running an auto ecu and only getting around 300km's, so i got a manual ecu but still getting a shit 300-350km's
i have been told that the fuel tank breather hoses could be old and cracked? letting the fuel vapor escape? any truth behind that?

[Brett_jjj]

Keeping the filters changed regularly,oil,fuel and air will help to get good economy.Also keep the Auto trans serviced.The filter and oil in the trans are easy to do yourself.I do mine every 15000k's,I do the engine oil and other filters every 5000k's.Filling the fuel tank,especially around town just wastes fuel as you have to drag around all the extra weight.Just fill it to half full around town and you will use less fuel.Extractors always make the engine run more efficiently.Definitely worth getting.And tyre pressure,run them at their maximum pressure.Also make sure the brake system is in good condition.If neglected it can end up with the brakes dragging on the disks.Not good for fuel economy.

[VS_Pete_1]

I run my tyres at 36psi

[hako]

Your fuel consumption sounds about average to me and I think unless you can do all the work yourself, like plugs, leads and filters yourself, any savings in fuel will possibly be less than the cost of the servicing.
The way I look at it is that your car has been pounding the bitumen fo 17 years and umpteen thousands of kilometres.....you cannot expect peak performance after 17 years unless you want to spend many dollars with sometimes no guarantee of return.

[Brett_jjj]

I keep my car serviced and I get excellent economy.If you drive around with a blocked up air filter or fuel filter and you will soon see the drop in economy.

[gandelff]

i have a vt v6 and have just finished the maths on its fuel consumption .think i am getting 10.79 ltr per 100 k if my tank is a 68 ltr dose that sound about right ?... i seem to be getting 640 km from a full tank it seems to good . i do highway runs sumtimes but still ?

[Paiste402]

its all about servicing and then driving style. my falcon gets 500kms per 63lt LPG tank only cause its tuned up properly, spark plugs, GOOD oil (no cheap crap in my engine haha) and a serviced transmission. And my falcon weighs a tonne being a farmont ghia with 2 bloody fuel tanks haha. Also you get more economy when u have half a tank opposed to a full one, half a tank of extra fuel is extra weight. But thats only if you really want to get into the nitty gritty haha. Check your air filter too, and dont just take the top of the air box off and go "cool its clean" cause all the dirt collects on the other side of the filter and alot of the sand and grit is almost unseeable until u give it a few bangs and see it all come out. And if your exhaust pipe is REALLY sooty then you may have an O2 sensor issue. My old EF falcon got 800 per tank of petrol and ran like a dream and the exhaust pipe was CLEAN all the time. I would wipe my finger on the inside and have nothing on my finger. But im not sure if Commodores are naturally a little dirty in the pipe.

But try to do less jack rabbit starts at the lights, as satisfying as they are, and see how much further u get per tank mate.