Fuel economy problems

Greggspies · Post by **Greggspies** » Wed Aug 18, 2021 6:54 pm

I recall balancing the SUs on an MGB in Switzerland in the rain in the 1970s to curry favour with a delightful Irish lady...

ujohnny · Post by **ujohnny** » Wed Aug 18, 2021 9:37 pm

Oldie wrote: ↑Wed Aug 18, 2021 5:28 pm Very odd - 41-mpg today seems about right - still can't see how 3-times the fuel can be injected into the engine without the smell of un-burned fuel, and do wonder if its a read out error rather than real usage - then again I guess you have checked that the fuel out of the tank has physically been used? Very curious and not something I have ever come across, even when I fitted 3-times over-sized jets onto SU carburetors back in the 80's - SU's and Webbe'rs - who can remember those??

Unless it’s a GPF regeneration, theoretically, ie on diesel it does 3 extra fuel injections to burn it in DPF so similar here is possible I believe

step2534 · Post by **step2534** » Thu Aug 19, 2021 10:52 am

I would think its a false read out. To run at 12 mpg the engine would sound terrible and would be struggling to run, I reckon it would be like running a carburettor engine with the choke fully out.

Alex_O · Post by **Alex_O** » Thu Aug 19, 2021 7:07 pm

Got it back from the dealer yesterday. They did a full software update and things seem to be back to normal, so I'm guessing it was a readout issue? Got to run the tank dry from topped 3 times and record the mileage so we can see what it's getting now, will keep this thread updated.

step2534 · Post by **step2534** » Thu Aug 19, 2021 10:03 pm

Good, false readout then, good old technology.

Deleted User 3629 · Post by **Deleted User 3629** » Fri Aug 20, 2021 2:42 pm

Run a car dry - really? I would not do that - just fill the tank when you normally would and clock the mileage - when you next fill again, clock the mileage and amount of fuel to fill - do this several times and then do the calc's.

Alex_O · Post by **Alex_O** » Mon Aug 23, 2021 7:17 am

Oldie wrote: ↑Fri Aug 20, 2021 2:42 pm Run a car dry - really? I would not do that - just fill the tank when you normally would and clock the mileage - when you next fill again, clock the mileage and amount of fuel to fill - do this several times and then do the calc's.

Dry = as close to empty as I want to risk taking it. I'm normally at the forecourt long before the warning light comes on, but they want less than 40 miles of fuel in the tank.

Deleted User 3359 · Post by **Deleted User 3359** » Mon Aug 23, 2021 8:46 am

In my experience the "miles to go" at low fuel levels is very pessimistic... I regularly fuel up when the light comes on, and get over 10 l in which means about 75 miles on my B4

Alex_O · Post by **Alex_O** » Mon Aug 30, 2021 7:19 pm

Agreed. My MTG stated 50 and I reset the trip cpunter just to see. Got 80 miles before I chickened out.

Alex_O · Post by **Alex_O** » Tue Oct 12, 2021 4:36 pm

We're back to the fuel system misbehaving again. Have been getting around 400 miles to a tank the past few full fills, but now the readout doesn't change for 60-70 miles then reports that I've used anything between 1/3rd and 1/2 a tank. Go the pump and fill until it cuts off and it's taking less than 10 litres. I'm guessing there's either another software problem, or hardware sending incorrect information. Can't get it into the dealership for nearly 2 weeks but hopefully they can find the cause this time around.

Fuel economy problems

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