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High fuel consumption?

955 views 29 replies 7 participants last post by  VEGA 
#1 ·
Hoy hoy,

The Astra is now back on the road and it fly's:D

Only query is about fuel consumption. How long does a tank last on these beasts?

I filled the tank up to full (well almost full, underneath the tank it is pushed in abit, being sorted tonight hopefully), with £25 worth of Optimax and I have only done about 150 miles and I need to fill it up again. I have to admit to booting it quite alot and loads of little journey's but surely it should last longer? It had an MOT on Saturday and the emisions wre low so there is no sign of running rich(??).

Any gen?

MattJ
 
#3 ·
The Astra starts up fine from cold, well straight away!! When the plugs were changed they looked fine aswell. Hopefully the dent in the tank could be giving me false readings on the petrol gauge?? Somehow??

How many litres does the Astra tank hold? I thougt it was about 45/50? I'm sure I can only squeeze about 30 odd in?

MattJ
 
#6 ·
yep - well, that's the sensor, same thing really.

if it wasn't working correctly you should get the ecu light come on.

the coolant temp sensor btw needs to be tested before you can be sure it's ok - you just need a multimeter and what resitances to check for when hot/cold - I forget what they are, someone on here will know I'm sure - 2k when cold or thereabouts, dropping away to a few hundred ohms when hot, iirc.
 
#7 ·
just to give you some idea MattJ, I usually get 370 odd miles out of a full tank of un-leaded. My tank is 50L. Thats a mix of most types of road but I'm mainly on A roads or country lanes.

Incidentally, my fuel computer usually says an average or about 33mpg.

When I floor it, the computer can say as low as 5 ish MPG! When cruising at 60-70 ish with light throttle, it can say 50ish.

Hope that helps.
 
#8 ·
I would stay away from Optimax, I feel there has been too much uming and aring about it to be sure so I just run Super in mine.

The only way to see real fuel consumtion is to fill the tank up, drive it for 300 miles and then see how much you can get in it. There isn't another way that is more acurate.

If you are getting less than 30mpg then you may have a problem.
 
#10 ·
one of the biggst identifiers for coolant temp sensor is struggling to get the car started when the engine is hot.

the tank is just over 40 litres, mine will take about 30-35 quid of super unleaded from when the guage is flashing.

The worst consumption i got with standard engine was about 250 miles from a full tank, the best over 400. The worst i got from throttle bodies was before getting the pressure right and was constantly about 150 miles. Now its better than standard returning over 400 from spirited motorway driving, and about the 250 from town driving.

Apart from your tank problem, which is obviously is not holding as much as it should, the consumption seems a little rough too.

whip one of the plugs out, see if its all black and sooty. It should be a nice misty buff if everything is ok.
 
#11 ·
hmm i just thought, is the vacuum hose from the throttle body to the fuel pressure regulator all intact and sealing ? Pay close attention to the rubber bend sections, the straight lengths are just hard plastic hose so "should" be ok.

the reason i bring this up is because the regulator is rising rate, at idle and low rpm when there is the most vacuum it closes off most of the pressure, at low vacuum i.e max rpm it opens up more fuel pressure. If the vacuum hoses was bust, it would then be mimicking zero vacuum, like it does at max rpm, which means max fuel pressure over whole rev range, which also means rubbish fuel consumption.
 
#13 · (Edited)
I think the hoses are ok 0dders, all seem in tact.

So do you think a sucked in bit of the tank could equal about about 15 litres?? It is quite a big suck!

The Astra is a bit hesitant on starting sometimes when hot, say, one in every 15 starts? I suppose that is not enough to warrent a new coolant temp sensor? What is the part number? If they are cheap I might just get one anyway.

MattJ
 
#26 ·
Cemesis said:

There are 2 different tank sizes in the GTE, one is 42 litres, the other is 52 litres.
very weird.....mine is a 1990 model with the peaked rev counter and almost 60 liters tank:rolleyes: ...(cos i filled up bout 55 once...)...weird cos it reads full gas on the digidash when i got around 30-35 liters...could that be a mismatch or the gauge isnt reading properly:confused:


also i got a metal tank.....was there a plastic 1 too?:confused:
 
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