The 27 / 73 outback fuel mix...

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The 27 / 73 outback fuel mix...

Postby Raider » Sat Jul 11, 2020 8:36 pm


Here is a big tip for all you outback adventure riders…

Head into a fuel servo with a near empty tank. In my case and the example used, the R 1250 GSA. Put 8 litres of diesel into the 30 litre tank before you recall it is not a diesel 4x4 you are filling. Top up the tank with 98 octane. Hope no-one saw what you just did and hope for the best…

That is the 27 / 73 outback fuel mix.

Ride a (very) few kilometres and as soon as the first of the 27 / 73 outback fuel mix clears (?) the injectors the mighty R1250 GSA, or other adventure bike, will splutter to a stop.

The big tip? The 27 / 73 outback fuel mix is a dud.

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Re: The 27 / 73 outback fuel mix...

Postby Digger » Sat Jul 11, 2020 9:35 pm


Very ballsy to admit to a stuff up like this! Tell me; how did you get out of this one. Who came to your rescue and how did you fix the problem?

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Re: The 27 / 73 outback fuel mix...

Postby boomer61 » Sat Jul 11, 2020 10:45 pm

I reckon either Mr BMW assist or Mr RAC Ultimate +.
OH for bike that dosen't have a brain that is that fussy about what it is digesting.
May have been able to drain and refuel then go again like in the olden days.
Now you will have to psychoanalysis with a computer to try and bring it back to a normal existence after its terrifying experience with a foreign substance.
Is the ICE for bikes!!!
Then you have to think of the poor owners mental state every time he goes out on his trusty bike thinking has it recovered from its substance abuse, but in the back of his mind he will be think can I trust it or have I scared the bike for the rest of its mortal life!!!
Mean while in the bikes little brain there will forever be the imprint of a fault code for substance abuse for anyone game to go looking for the criminal history of 1 previous
careful owner who succumbed to the fuel substance abuse of his poor bike.
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Re: The 27 / 73 outback fuel mix...

Postby BillB » Sat Jul 11, 2020 10:52 pm

Is that covered by insurance? If you have it insured with BMW they do a new for old deal.
I must admit I did something similar about 8 years ago. I put about 8 l of 98 petrol in my diesel Rover 75 before I realised they had changed the bowsers at the station and the hoses were in different positions from where they used to be.. I had a 60 l tank in the car and filled the rest with diesel. I went for a couple of fairly long trips to burn up the fuel quickly to get rid of it, refilling the tank by topping it up many times to dilute the petrol. That car kept going right up till I sold it to the mechanic who serviced it back in March this year. He is still very happy with his new purchase as far as I know.
Petrol motors probably react a bit different to diesels thou.
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Re: The 27 / 73 outback fuel mix...

Postby Raider » Mon Jul 13, 2020 2:33 pm


The bike was picked-up on an RAC flat-bed truck and taken to Auto Classic to sort. Could have also used the service provided by BMW. Would have probably ended up with the same truck.

If I had a suitable hose with me and a better understanding of the issues I could have pushed the bike to a quiet spot and drained the tank. Problem sorted - provided I actually drained ALL the diesel. Even easier if I hadn’t topped-up the tank.

Given that I started the engine and rode the bike a short distance the effort to sort the problem multiplied - big time! At very least I would have needed a good tool kit and plenty of battery power to crank the engine quite a bit with the plugs out - required to flush diesel out of the system. No issues, however, with the electronic engine management...

It turns out I didn’t have a 27 / 73 outback fuel mix in the tank. Instead I had 8 litres of diesel in the bottom of the tank with the 22 litres of lighter 98 octane on top. Once though the injectors the bike was trying to run on diesel alone. Not good for the engine or for the catalytic converter.

The up-shot? Don’t put diesel into a tank designed to supply gasoline to the engine.

From now on I might carry a just-in-case hose… I could grab the one I have for transferring fuel on the DR. Then again, maybe I will chance it as this is a first in many many MANY tank-fills.


PS: In case you are wondering how I could have made such a mistake...

I have two diesel vehicles that are regularly filled by me. On the day, as I turned into the new BP servo on Welshpool Road the pricing sign had the usual list of prices but for diesel it indicated only "truck diesel". That piqued my interest as I figured that the price for the average punter was probably quite a bit higher. So, when I arrived at the pump...
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