Fuel consumption has suddenly got a lot worse

[Blandy199 31]

Morning all, my 2014 nc750 dct seems to be using a lot more fuel than it did previously. I have had the bike for 2 years now just commuting to and from work using the same route. i have always comfortably managed to do all week on one tankful, around 250 miles with the trip computer showing around 84mpg. Now, for the last 2 weeks I have only been able to manage 4 days and 200 miles with the trip computer showing 76mpg before having to fill up again. I am doing the same route at the same times using the same Shell petrol with no obvious brakes binding or performance loss. The weather has not been great with either strong winds or sharp frosts but that's nothing new and has never seemed to have much effect on fuel consumption before.

The bike has been regularly serviced all it's life.

I was wondering if anyone else had experienced this and if so, what the problem was.

[splke 1,253]

maybe something to do with the e10 fuel ?

[Blandy199 31]

Thanks Spike, It's been on e10 for a long time now, I must have been using it for over a year now. I'd be surprised if that was it but might try a tankful of premium fuel to see if there is any significant difference though. Last time I tried that on my old Silverwing scooter, whilst there was a slight improvement in fuel comsumption using the premium fuel, it was negated by the extra cost of said fuel.

[Slowboy 20,530]

Silly question, but is it the colder weather? My NC700x was less economical in winter on my 30 mile commute, I just put it down to it taking much longer to warm up on days when it was between 0 and 5 degrees.

 

It was surprising what a difference tyre pressures or wet roads made as well. I think when your not using much the difference is more noticeable, maybe….

Edited January 18, 2023 by Freeroader

[Xactly 5,435]

I agree with that.

[Scootabout 2,263]

Other thoughts:

Petrol leak (probably not, though, if you're still getting 76 mpg),

Clogged air filter

Fouled spark plugs?

[MatBin 5,097]

I would suspect cold weather and air filter.

[Blandy199 31]

Thanks Spike, It's been on e10 for a long time now, I must have been using it for over a year now. I'd be surprised if that was it but might try a tankful of premium fuel to see if there is any significant difference though. Last time I tried that on my old Silverwing scooter, whilst there was a slight improvement in fuel comsumption using the premium fuel, it was negated by the extra cost of said fuel.

[Skidt 1,315]

As @Freeroader and others have said, I suspect It’s the low temperatures. 

Had mine out on Sunday. It’s been properly serviced and a new air filter recently, tyres pressures good, chain lubed etc.

I normally, under varied riding, can get anywhere between 72mpg (16 mpl on display) and 85mpg (19 mpl on display).
80ish mpg (18 mpl on display) is the norm I’d say during the warmer months. 
On Sunday I was getting 67ish mpg (15mpl on display).  I’m sure @Andy m will be able to give a far better explanation about fuel / air ratios and air density v ambient temperatures at this time of year.

There may also be an element of poor quality fuel involved. On a recent trip down to Devon in our petrol Octavia, I was shocked to see the fuel gauge dropping and the mpg drop like a stone to 30mpg. So much so, that I stopped early in the journey, checked the oil and tyre pressures again, even though I’d done so the day before, just in case I’d picked up a slow puncture that TPMS hadn’t alerted me to. All good. 
 

On a long run like that at motorway speeds, I’d normally expect to be in the low 40’s mpg. When we got down to Devon, we filled up with a more premium brand petrol and on the way back, hey presto, low 40’s mpg again. 

We’ve always used the same non premium brand petrol station for years, as it’s the closest one to home, about 2 miles away. In fairness to them, we’ve never had any problems before. I tend to use it to fill the bike up on the way home from a ride out as well, as it’s a good 3-5 ppl cheaper than the nearest premium brand station. 
Both bike and car had been filled up at the same place within a week or so of each other. The bike has now been filled up at a more premium brand station to see if there’s a discernable difference. Won’t know until the icy weather clears up a bit.
I suspect that the garage may have just had a poor quality batch of fuel. 
 

[Blandy199 31]

Thanks for your suggestions, and whilst it has been cold and wet lately, it's no different to the last 2 winters and this hasn't happened before so dramatically. Of course there is some increased fuel consumption with adverse weather and not carrying as much speed around the bends etc, yet i've always managed to do a full week's commuting on one tankful before. Tyre pressures are checked weekly, I certainly haven't been using it in dusty conditions (not much chance of that round here at the moment) so I wouldn't supect the air filter to have suddenly clogged but will check it out anyway.

[Andy m 23,585]

E10 means it has at most 10% paint thinner contamination. They can supply E5 or E0 from that pump if that's what they decide to do. We had E10 labels on the pumps a good 6 months before they started watering the petrol. I've had tank fulls through the repmobile that suggest E5 came back for a few weeks. It's a transition period and one with a volatile energy market, the wholesale price of E5 ordered a year ago might be lowerthan E10 now and if the supermarket can't store it they have to sell it.

 

Test and check as suggested above. The cold starting function makes a big difference.

 

Andy

[Grumpy old man 4,682]

Another one here tends to agree with the cold weather theory my Nc consumption drops in the winter and the wind makes a big difference. 

200 miles before fill up! How long had the gauge been flashing at that point? 

[Blandy199 31]

The guage is usually flashing around 25 miles before I stop to fill up, as I mentioned, normally that is at around 225 miles but now is at 175 miles. 

As many of you have already pointed out that the cold weather will have an effect, it didn't have any really noticeable difference before Christmas when we had a cold snap.

I'll have to see if it improves once it warms up a bit. I'll let you know how it goes, and thanks for all your thoughts on this.

[Xactly 5,435]

In its current state you are getting better mpg than I have ever achieved on my NC750X manual.... I know that there are several factors that can influence mpg, but tbh I reckon there's little wrong with it. I've always run mine on E5 as well, except for a tankful when I couldn't get any (and I don't think there's actually any ethanol in the E5 I buy because it lacks the distinctive aroma (well, stink).

[Steveg 1,031]

my 2019 nc750x used to drop from normal 80 mpg to 75 mpg in the winter on 50 miles commute 

 

my dl1050 has dropped from 60 mpg to 56 mpg doing same commute 

 

I would put it down to the cold weather 

 

Cheers Steveg 

[listener 11,213]

This is the chart for my previous NC750X DCT.

Bought in March 2015 and owned for four years (W at bottom = winter period).

 

I've noticed a similar winter drop on all my bikes going back to when I started recording fuel consumption on the KLE500 in 1991.

 

[jeremyr62 2,573]

30 minutes ago, listener said:

This is the chart for my previous NC750X DCT.

Bought in March 2015 and owned for four years (W at bottom = winter period).

 

I've noticed a similar winter drop on all my bikes going back to when I started recording fuel consumption on the KLE500 in 1991.

 

Good data. I don't ride my NC much at all in Spring/Summer so maybe this explains why I never see >70mpg.

[Tatts 675]

I always thought engines were supposed to run better in cold weather?!

 

As others have said, look at replacing the air filter and plugs.  Whilst you're in Halfrauds or other motor spares emporium buy a bottle of RedEx petrol treatment.  It's pretty cheap, and will clean the fuel & injector system.  I use it in both my bikes twice a year, and every 4th fill up in the car.

[Jamesc 3,656]

Cold air = more dense, which is good for engines but bad for aerodynamics...apart from taking longer to warm up including tyre pressures 

[Andy m 23,585]

Don't forget the technology on bikes is to a price, enricher functions are on/off. 

 

The biggest saving if not already done is to keep the vehicle in a garage. Heating the garage would be an interesting calculation at current prices and the variation in those prices.

 

The Scandinavians fit CV's with sump and fuel heaters with much more subtle controls than your basic on-when-cold cold start EFI loop. Connections via telematics to a calender is done and to weather forecasts probably coming if not already done. If the savings in fuel pay for the tech they'll do it.

 

Andy

Edited January 20, 2023 by Andy m

[Xactly 5,435]

2 hours ago, Tatts said:

I always thought engines were supposed to run better in cold weather?!

 

As others have said, look at replacing the air filter and plugs.  Whilst you're in Halfrauds or other motor spares emporium buy a bottle of RedEx petrol treatment.  It's pretty cheap, and will clean the fuel & injector system.  I use it in both my bikes twice a year, and every 4th fill up in the car.

They run better in damp weather.

[Steve Case 955]

Mine has heavier consumption when its cold, i see it every winter.

[jeremyr62 2,573]

1 hour ago, Andy m said:

The biggest saving if not already done is to keep the vehicle in a garage.

And not ride it. Yeah that will save fuel alright.

[jeremyr62 2,573]

3 hours ago, Tatts said:

RedEx petrol treatment. 

Snake oil I think, or very  close to it. Decent petrol has all the detergent you need.

[Andy m 23,585]

Does Redex also contain an Octane booster? While I doubt the improvement covers the cost, as a range extender on the current potato water fuels it could be worth a go?

 

Andy