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Fuel gauge erratic reading

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Robertsitrep9 View Drop Down
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    Posted: 05 Jun 20 at 04:24
MULTI VAN BEACH 2006 2.5 lt 
Standing start to 30 kph 45 lt per 100 k then down hill 70kph 0.2 lt per 100 k ,and it is more erratic up and down the gear change,
Should be reading 8 lt to 12 lt  per 100 k any suggestions? BB
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Post Options Post Options   Thanks (0) Thanks(0)   Quote gregozedobe Quote  Post ReplyReply Direct Link To This Post Posted: 05 Jun 20 at 11:59
The instantaneous consumption figure should vary a lot according to how much throttle you are using.  It's more about how hard the engine is working, not what speed you are doing.  If coasting down a steep downhill it could go down to 0.0

Is the average consumption figure reasonable ?  When driving gently on the highway my van usually got 7.5 - 8.5 (which was usually about 10-20% optimistic when I compared it with actual diesel used via the fill-to-fill method).



Edited by gregozedobe - 05 Jun 20 at 11:59
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Robertsitrep9 Quote  Post ReplyReply Direct Link To This Post Posted: 06 Jun 20 at 01:52
Thanks for the fast response,all my driving habits with this vehicle have been gentle on the pedal(too old to do other wise)Went for a drive up the freeway yesterday 29.8 k on a full tank used 2.47 lt .and again the readings were as such 100 kph 4lt to 100 kl  slow down to 80 kl and increase speed to 100 kph fuel reading 48lt to 100 ks,there must be a electrical malfunction some where.
Have made inquiry to local friendly VW dealer $165 to have a look only. A little daunting to my way of thinking.BB
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Post Options Post Options   Thanks (0) Thanks(0)   Quote BeJay Quote  Post ReplyReply Direct Link To This Post Posted: 06 Jun 20 at 10:10
Originally posted by Robertsitrep9 Robertsitrep9 wrote:

MULTI VAN BEACH 2006 2.5 lt 
Standing start to 30 kph 45 lt per 100 k then down hill 70kph 0.2 lt per 100 k ,and it is more erratic up and down the gear change,
Should be reading 8 lt to 12 lt  per 100 k any suggestions? BB

I don't think there is anything wrong with your consumption readout (not the fuel gauge, that just tells you how much fuel is left in the tank) as Greg says the instantaneous consumption figures will vary wildly, e.g. standing start to 50 kph with your foot flat to the floor in each gear is going to give you a very high figure for lt/100k (maybe your 45??) whereas doing 100kph on a slight downhill with a feathered throttle is going to be a very low figure for lt/100km (maybe between 1 to 2 lt/100km), the instantaneous figures are just what it's doing at that precise second and are totally irrelevant in any practical sense as far as working out your average fuel conumption, the only figures you give that are relative to your average fuel consumption are the 29.8 km using 2.47 lt which works out at 8.29 lt/100km, like Greg says the only real way to work out your average fuel figures over all your different driving styles (e.g. local/urban/motorway etc) is to fill the tank then dont fill it again until you've used at least 3/4 of a tank then divide the km you've covered by the ltrs you've used = km per ltr, then divide 100 by that figure to get lt/100km.



Edited by BeJay - 06 Jun 20 at 11:15
NIL ILLIGITIMUS CARBORUNDUM
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Robertsitrep9 View Drop Down
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Post Options Post Options   Thanks (0) Thanks(0)   Quote Robertsitrep9 Quote  Post ReplyReply Direct Link To This Post Posted: 07 Jun 20 at 03:08
will try your advice on a long run using 3/4 of a tank ,thanks for the detailed explanation. BB
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