Fuel consumption - 100 miles to a tank!

[Beancounter]

Hi all,

It seems that my Rockster has turned into an unleaded-aholic.

I used to get about 145 miles into a tank before the fuel light came on. This was with a pillion, riding 80 miles a day (60 on DCW/motorway and 20 in London traffic).

Now I'm getting to 95/100 befor the fuel light introduces itself. The only difference in my ride is that it's 40 miles a day (20 motorway, 20 in London).

I was subjected to a rear end violation in December. Resultant damage included the can crumpling and creasing quite badly. The bike ran, but was backfiring quite a bit more. Could this have caused the ECU/CDI to start chucking more fuel into the cylinders?

Any other thoughts and suggestions gratefully appreciated.

Thanks in advance.

Cam

[riceburner]

You really don't have much luck do you mate!

I'd get it looked at, unless you're letting it rev at 2,500 permanently when off-throttle in London (ie you've left the fast-idle up), or doing something similarly odd.

[ibux]

You might want to check out this
http://r1150r.org/board/viewtopic.php?f ... ion#p95081

As said in the post I had a fuel leakage, and it wasn't easy to spot at first.
But it was the increasing fuel consumption that got me checking my bike more throughly.

[boxermania]

Beancounter

Many things could have happened to get the mileage down....based on your post I'll go down the prioritized list;

First, I have to say that I had a good chuckle with your proper statement "subjected to a rear end violation in December" forgive me, but stateside I don't want to have ANY type of rear end violation....but I digress.

1) The can got crunched and consequently the exhaust flow has been restricted - The easiest way to check it is to see if you can get the bike to the red line....do it safely, in any event, remove the can altogether and ride the bike for a tankfull. I know you might have a bobby call your attention, but tell him that it fell off and there is one on order. Was the cat converter crunched too?

2) Have they inroduced the E10 gas in the UK......gasoline with 10% ethanol. If you have been using this gas as opposed to the regular gas, your mileage would have dropped ~ 20% or 28 less miles per tank.

3) A gasoline leak - This would be hard not to notice

I don't think the ECU/CDI have been compromised, so my best and only choice is # 1. Good luck and let us know what you find...

[jfslater98]

remove the can altogether and ride the bike for a tankfull. I know you might have a bobby call your attention, but tell him that it fell off and there is one on order. Was the cat converter crunched too?

Results from the can-less conversion should be a minimal increase in noise, unless something happened to the cat. Not being a Londoner, would the coppers have a visual problem with no can? I would imagine it's the noise that gets them . You may have seen the various posts on the DJ mod, you may even wind up keeping it that way.

[MikeCam]

Regardless of when the low fuel light comes on, how many miles are you getting per tankful? How much are you putting in each fillup? Has your consumption actually changed?

The very first thing I'd suspect is a bad fuel sensor float. Then the fuel map and exhaust restrictions.

[zax1150]

Firstly whereabouts in london are you?

as my usual first port of call would be to interagate the ecu, see what's recorded for the thump, most common is TPS is slightly out of alignment. bit like when the rubber bungs on the TB's balance points are cracked wrecks your fuel economy

[riceburner]

Beancounter

Many things could have happened to get the mileage down....based on your post I'll go down the prioritized list;

First, I have to say that I had a good chuckle with your proper statement "subjected to a rear end violation in December" forgive me, but stateside I don't want to have ANY type of rear end violation....but I digress.

1) The can got crunched and consequently the exhaust flow has been restricted - The easiest way to check it is to see if you can get the bike to the red line....do it safely, in any event, remove the can altogether and ride the bike for a tankfull. I know you might have a bobby call your attention, but tell him that it fell off and there is one on order. Was the cat converter crunched too?

2) Have they inroduced the E10 gas in the UK......gasoline with 10% ethanol. If you have been using this gas as opposed to the regular gas, your mileage would have dropped ~ 20% or 28 less miles per tank.

3) A gasoline leak - This would be hard not to notice

I don't think the ECU/CDI have been compromised, so my best and only choice is # 1. Good luck and let us know what you find...

Boxer - we don't get ethanol fuel in the UK, I don't think it's even legal tbh.

[Biff's R]

Check your air filter, too. I noticed 3-5 mpg difference after replacing.

[boxermania]

zax1150

Good call on the "bungs",as any ingress of air will lean out the mixture while the O2 sensor via the ECU is trying to enrichen the mixture, however, the mileage loss is too great to be from that source.

[NoRRmad]

We still don't know if your milage is down, or if it's a problem with your low-fuel warning system. Have you actually computed your milage yet?

[tweetyoost]

Hello

I have exact the same problem with my 2004 twin spark rockster, and I tried everything to get it right but nothing has helped so far...

I checked:

Spark plugs > replaced
Air filter > replaced by a K&N
Valve adjustment done
TB synchro done
Reset the motronic done
TPS sensor voltage > 0,36V done
Putting a can of fuel injector cleaner in my fuel tank done

And I still have the fuel consumption problem... I'm doing about 150km before the led goes on (that's about 95 - 100miles)

Could the lambda sensor (oxigen sensor) be the problem? and how to I measure it?
Or maybe leaking fuel injectors?

I've got only 18.000km..

I will keep watching this topic, till we both have found our fuel consumption problem

[boxermania]

tweetyoost

Now it seems we have a rash of 100 mile tanks......

Where do you live? How do you ride? Are your excursions all in stop and go traffic? At what rpm do you go into the next gear? What octane gas do you use? Any recen addition of Ethanol to the gas where you live?

Right now I have absolutely no idea.....in your case.

[tweetyoost]

No ethanol as far as I know:p

I live in Belgium, switch to next gear on 4-5-6-7 Krpm depends in what mood I am:p

My record was 180km's with one tank till the green led.. and on sport style I'm doing 145km's with one tank..
so the differents is not that big.. and 180km's (112miles) is still not a normal tank milage..

I use 95 or 98 octane gas but I'm not noticing any differents..

I'm trying to find a solution by myself.. not planning to give all my money away in a beemer garage..

[zax1150]

How are you guys riding?

I mean I know I have a lead wrist

I'm still bedding the engine in atm, but @ an avg 110Mph (open road) my avg is 9.8mp/Ltr, I know the float does tend to rise under constant acceleration which results in the low fuel indicator @ 15-16ltr
whereas round town the norm is 18ltrs for low fuel indication city driving avg is 7.2mp/ltr so 130miles to a tank

So questions are as follows

1# when you've done your 100miles to a tank (city driving) how much are you putting in?.....less than 16ltrs then possible faulty float (seen that one a lot, as they're pathetically unreliable:roll: )
2# tweetyoost you say replaced plugs all or just the main?
3# tweetyoost you say you reset the ecu, what with? what interface did you use?

[CorvuS]

My Rock runs about 1l./14 km
Sometimes a bit better but still roughly thesame as my car...
I use thesame fuel. (Euro 95) as tweetyoost
My Fuel led starts burning at about 150-170 Km.
When I fill her up after 200 Km, about 14 litres go in.
According to the little book (wich in my case only mentions the R1150R Roadster) Fuel consumption should be around 1/17,5 ( 5.7 /100 Km)

The R1150R of my buddy runs 1l/17 km
But I understand the roadster has a different tuning than the rockster.. (can't find info in the little books about that)

If there's some good solutions I'd be happy to know. And offc, Ill start checking some things out...

[zax1150]

But I understand the roadster has a different tuning than the rockster..?

on the ecu no.....on the drive ratio's yes...roadster is about 4250rpm @ 70mph...the rock being 3500rpm

[boxermania]

As a point of comparisin.....my bike a 02" R1150R with mods could run at all difrent throttle openings and would require about 15 liters every fill-up. The typical distance traveled was 273 kms when the low fuel light would come on and would fill with ~ 4 gallons of 89 octane gas. I very seldom deviated +/- 0.375 liter from these numbers.

The above works out to an averafe of 18 km/liter or 42+ miles/gallon. Of course I had the low highway gear which works out to 70 mph = 112 kmh @ ~ 3500 engine rpm.

[zax1150]

actually boxermania makes my point, the overdrive ratio's make a big difference,

my old 04 roadster would only return 12.5mp/ltr (20km/ltr) thats with the low fuel light coming on between 15-16litres

but that's with Brisk DOR14LGS plugs (std engine) very popular with the single spark riders as they kill the surge problem, touch more power & better economy

DOR14LGS-T is what I use on my much modded rock, boxermania you might like to give 'em a try, much cleaner burn

[tweetyoost]

I replaced the main sparks by HALO spark plugs (same as brisks) and let the twin tiny sparks the same..
If I have driven about 200km's(125miles) I can tank 17L (8.5l/100km)

Or is it just a rockster thing?strange.. it's the same engine as the R1150R...
everything I know inclusive circuit racing does not get above 7l/100km MAX! and my MIN is 8l/100km or so..

so.. there's something wrong;)