Well folks I have now had a look inside the fuel tank and it does not look good. The fuel pump, sender, filter and hoses were all out when I got the bike and there has been a small amount of fuel in the very bottom of the tank (about 50ml) for in excess of five years. The photo below is not good but as you can see there is a whole bunch of black stuff around where the fuel pump mounts. I can only assume that this is the remains of the rubber vibration mount that started to perish. The whole tank also seems to be covered in a yellowish looking lacquer that wipes off rather easily.

Is the inside of the tank supposed to be this color or should I clean all this out prior to replacing the fuel pump etc? What is the best method for cleaning the fuel tank out?

NO NO NO and yes I am shouting the inside of your tank should look and I am not joking, an immaculate silver aluminium colour and all that muck is as you say the remains of the damper surrounding the pump. You do need to clean it out thoroughly so there are no more bits of muck in there. I would throroghly wash it out with petrol and using a long scrubbing brush remove all of the rubbish. Lots of washes with small amounts rather than one with a lot is the way to go, do it outside away from sparks and flames and so you don't inhale the petrol vapours.

Don't do as a good friend did which was use his mum's cylinder vacuum cleaner to suck the fumes out the tank to dry off the petrol prior to coating the inside with rust preventer. The vacuum cleaner took off literally like a rocket blowing the end off, his mum was not pleased. I didn't witness it but heard al about it from her when I got there a few minutes later (I think most of the street heard her too).
Regards,
K-BIKE

Hi there,

To back up what K-BIKE says, the inside of the tank should be gleaming, I have just spent several hours over many days cleaning one of my tanks out. I found too that some of the goo (technical term) was removable by old rags and then clean out with bicarbonate soda and warm water, let it work over night if possible - rinse out - start again - soak - rinse - rag out - soak - rinse - rag out - you get the picture, its hard work. The black stuff is where you have said, its the old rubber mount and possibly fuel hose too, best to replace hoses and mount rubber and whilst out give the pump a good flush and probably best to replace the filter otherwise you may find that it cloggs the system and you don't get the volume off fuel required.

Best of luck!
Ian

good work dave ... youll get there mate .

OK gents a bit further info required. It has been suggested that I use Carby Cleaner to get rid of the ULP varnish inside the tank and that this should also help get rid of the 'melted' rubber in the tank as well.

Anyone else used this in the tank? Will it work? Does it damage the aluminium?

All help appreciated. If you think I am looking for the easiest way of doing this job.......You would definately be right. Being in the shed at this time of year is a bit cool.

id be prepared to use lots of old rags dave .....probably paint thinners would be a good start on the rags as they would absorb lots of the gunk as well .

Well the tank is now reasonably clean when compared to the original. Just have to blow out the dust and she will be ready to go. The little bits of rubber that slide on the side of the pump mount between it and the tank sidewall are missing. Will this present a problem as I can't find them on the parts list?











What did I learn? Cleaning a tank is a painful experience when you have fat arms. Being the lazy sod I am I looked for the quick way and stumbled across a relatively easy way by accident and after much scrubbing with a plastic brush. As a cleaning medium I used carby cleaner. As most carbies are aluminium in nature I figured the cleaner would not be caustic. I spent half a day cleaning and then left the tank overnight. The next night I found out the carby cleaner had softened the yellow fuel deposit and when it dried it turned to dust. A simple wipe with a rag and off it came. Did this a couple of times for some really soiled bits and the result is the pictures above. Now just have to get the air in there and blow out all the dust to ensure the new fuel pump doesn't get clogged up. I also learned to use the carby cleaner outside and with a mask. The safety data sheet makes for fun reading. Not.



There is a small pipe that runs to one of the overflows on the right rear of the tank. It points downward just under the fuel cap mounting ring. Does it have a hose on it? Just wondered as it has a lip that looks like it holds the hose. The pipe itself is smaller in diameter than the ones for the fuel pump outlet and return. You can just see the end of it in the first picture above.

That tube goes to the filter on the bottom of the fuel pump. You will see that the filter is round and pushes onto the vibration damper rubber that the pump sits in. Please don't ask what the hell does it do because I don't think that even the all knowing all seeing boffins at the great BMW factory in the sky know either.

It is just there

hi dave ....yes.... there is a basket on the fuel filter with a take off of 1/4 inch ...this pipe is only maybe 6 inches long ...and squeezes down in that elongated point of the fuel pump holder area ..... and up to that aluminium pipe that flows down to the under tank outlet....



although i really dont know the benefits just yet .....we have seen issues of fuel over flow /expansion of fuel bleeding out that pipe and further down to the under tank "catch cup " and then out to near the swing arm area ........

to me there should be a really porous line used there to allow vapours rather than fuel to be presured out to the under tank collector .



hope this helps mate ......good write up about the carbi cleaner experiences and result

Now I am a bit confused. I thought the fuel return from the injector rail goes onto the bottom of the fuel filter (or doesn't this have a hose on it?). The one I am talking about is only 3-4mm in diameter (much smaller than the two other fuel lines) and goes directly to the right rear of the tank and then into the overflow doover under the tank.

yep your right mate about the return line (external ) and fuel feed out ......but i guess you never saw it before the cage and suspension system melted ....the fuel lines are 8mm internal diameter from the pump to the filter and then to the outlet (at the bottom of the tank ) this little piece of pipe we talk of ,,,is probably new to you ... there are exploded diagrams on the real "oem" sites for explanation ... number 15 in this pic

CanberraDave wrote:The little bits of rubber that slide on the side of the pump mount between it and the tank sidewall are missing. Will this present a problem as I can't find them on the parts list?

A member in the K11OG forum did make a slit in two pieces of submersible gasoline hose as a substitute for this parts.

Inge K.

Well folks an eventful weekend so far. Fitted the new fuel pump. Didn't have any small hose to go on the breather so that will happen next week.

Pulled the rear diff and gearbox off. Greased everything. Have a noisy crown bearing. Bugger. Mate has a second hand diff at home he is going to check for me.



Refitted everything and turned on the key. All lights as they should be. Pressed starter but just turned over. No firing at all. Tried a bit of start ya bastard, but that didn't work either. Pulled the new plugs and they are as dry as a bone. Checked the fuel rail and definately getting fuel, but the rail was pretty dirty. Replaced it with a spare but still no go. Checked the injector relay and the ECU with spares and still no joy.



So now I have 4 injectors on my bench waiting to go to the cleaner on Monday. The bike has sat for 7-8 years and the fuel hoses were disconnected and not sealed. My guess is that it wasn't the off fuel that stopped the bike but some of the rubber gunk getting down to the injectors and clogging them up. Does anyone know what it costs to have the injectors cleaned and tested? Will the people supply new 'o' rings or do I have to get them from BMW seperately? Have I missed something simple?



So all in all a mixed bag so far.

You wont need to go to BMW for O rings, all the Ford falcons of the 90s had the same injectors and O rings.

hey dave,,, i wonder if the pins are just stuck in the injectors ...maybe a couple of days in a jar filled with some fuel might loosen them up a bit ? maybe even overnight ?

Dave, BTDT on both my K's. Had to discard both set of injectors, no amount of cleaning would clear them. They remained seized. On one bike I bought the refurbed Ford injectors on ebay for $100. On the other, I bought of used set of injectors for $40 on ebay. Here in Canada it is $100 to clean injectors, so for me it was an easy decision.