Fuel consumption skyrocketed since flat battery

[Twindub]

My battery was flat when we came back from holiday so after a recharge my fuel consumption is so bad it’s almost like it’s leaking somewhere. £30 of fuel got me 38 miles. No drips that I can see or smoke . Any ideas ??

 

[DaveD]

My battery was flat when we came back from holiday so after a recharge my fuel consumption is so bad it’s almost like it’s leaking somewhere. £30 of fuel got me 38 miles. No drips that I can see or smoke . Any ideas ??

How are you measuring that fuel consumption?
The gauge might not be accurate.
I suggest you fil it to the brim, use the van, then fill to the brim and calculate your MPG based on fuel used and miles covered.
I really can't see how it can be so bad, your figures suggest less than 9MPG.

 

[Twindub]

I know, it’s ridiculous, you can almost see the needle dropping. It went to 20 miles to empty , I recorded the mileage and put £30 in , it’s then said range was 175 miles. It’s now down to 40 miles left and I have done 38 miles .

 

[Twindub]

I initially wondered if the flat battery had reset the computer data that calculates the fuel consumption but it’s so bad I’m not sure it can be that.

 

[DaveD]

I know, it’s ridiculous, you can almost see the needle dropping. It went to 20 miles to empty , I recorded the mileage and put £30 in , it’s then said range was 175 miles. It’s now down to 40 miles left and I have done 38 miles .

You are relying on the van entirely to tell you how much fuel you are using per mile, it's just not an accurate method.
The only way to know for certain if your van has a real problem is to calculate your fuel economy the way I described above.
I'm not sure if a flat battery can affect the tech that shows your range, there are other members who are far more expert than I am on that sort of thing, is the battery fully charged now?

 

[Mocko1962]

Dead batteries cause all kinds of issues … it maybe causing the fuel display / indicated mpg useage issue … via BCM

Do a hard reset on the BCM …

Fill it completely and retest .. worth a go …[Guide] Full Van ECU Reset (Capacitive Discharge) -- How I Done It --