K100RS 10km of glory

[K-Boom]

Hi All

 

I'm so down and out with this K100RS and since I waited so long to get a bike again and saved to get there as well.

 

I got this bike on Saturday and when the owner started it, then it started up the first time no problem. We stood and chat about the bike for a few minutes and then I opted to take it for a run just down the street and once again it started fine and all in order. I however noticed that the headlights are not in the "on" possition but left it there as I cruized down the street. Stopped and parked the bike and did the payment before I geared up and took off but switched on the headlights. The bike went super fine for about 10 km and just as I got to Lynwood off-ramp, the bike just died on me and tries to start it but nothing as the motor just turns and turns.. So I figured it might be low on fuel and pushed it with my frail legs ( Having Multiple scresoses ) to the garage where I filled it up. Tried to start it again but without any luck and opted to go fetch a trailer and tow it back home where I checked the fuses and found the 2nd fuse from the bottom to be blown ( 7.5 ). I was exstatic since I believed this was the problem and I replaced the fuse and geared up ready to go for that long awaited ride but as I tried to start the bike, it just turned and turned till my battery went dead.

 

I opted to jumpstart the bike from the car but it still kept on turning but this time with an ocasional glimps of something wanting to start. I then thought it might be a battery problem and went and got me a charger and charged it over-night. This morning I was so excited and in the freezing cold garage went to start the bike but it just turned again and then it blew that fuse again. I tried to listern if I could hear the pump but I don't know how it sounds so here I am with a K100 that is of no use to me and everybody is laughing at me once again since I told the wife that this bike is in a very good condition. I'll have to add that this bike came with 2 extra sets of clocks ( instrument panels ) so can't realy say what the mileage is.


Due to my lack of technical skills and my weak arms and hands from my illness, I have no option than to have it towed to BMW but I just don't have the finances for that since I sqeezed out every last cent to buy this wreck lol so I think I'll be selling this bike for spare parts and accept my losses and start saving again. These things always happen to me and after the last few months with my financial hardship, I'm broken with dissapointment once again.


If it's just a dodgy battery then it's good or perhaps just a dodgy pump then that too is ok. The last owner rode this bike to work and back every single day without any problems till I got it and did that 10km and killed the beast. I have read all the tech forums and I have the workshop Manuel as well but I just don't know.


Regards

Bobby Muller ( South Africa )

[Rick G]

Hi Bobby welcome to the forum.
Sounds like you got had a bit but don't dispair just yet.  Most likely the fuel pump has taken a big gob ful of muck and quite likely put it into the fuel filter so blocking the fuel supply.
You should hear the fuel pump run for 1.5 seconds as soon as you turn the key on and then each time you hit the starter button.
My advice is to remove the fuel cap by removing the four screws you see after opening the cap, this will give you access to the pump and filter.
The line that goes from the top of the pump to the filter, remove it from the filter and with the end of the line facing down into the tank or a bottle of some sort turn the key on and a heap of fuel should come out. Try to stop the flow with your thumb over the hose end, it should be very hard to stop if not impossible. If flow is weak the pump is blocked or just plain shagged.
Remove the filter and place it on the hose and try the same to find if the filter is clogged.
It probably will be where the problem is but the pump cant be cleaned so a new is in order. Have a hunt through the Lieberry card index and check the thread about replacement pumps.
The OEM pump is not at all hard to replace with an aftermarket. Almost any Fuel injected car of that era with a bosch system will have a suitable pump.
It has to be capable of pumping about 30ltrs/ min at 35psi and have 5/16in  or 8mm hose fittings.

[K-Boom]

Thanks Rick

I will do just this later and see if any fuel comes out when pushing the button. Another thing is that that dial on the right hand side does not move more than a mm even when the battery is fully charged. Could a worn battery cause all of this even if the starter makes the motor turn over and over again ?

[frankenduck]

We need to know the year of your K100RS in order to help you.  If it's 89 or earlier then you should not hear the fuel pump until you press the starter button.

[K-Boom]

It's a 1985/86 model RS

[frankenduck]

Replacing a blown fuse without determining what caused it to blow is just wasting another fuse.

Before you remove the gas cap be sure to clean out the Philips heads screws with a tack or pin and use a good screwdriver with some downward force to break the screws free.  The fact that they screw into the dissimilar aluminum of the gas tank often causes corrosion to build up in the threads.

Your problem may be as simple as a very clogged fuel filter.

Parting the bike out would be MUCH more work than fixing it so I'd see that as a very last resort.

[mystic red]

Could a worn battery cause all of this even if the starter makes the motor turn over and over again ?

No, sounds like your battery was good. My bets on the fuel supply like Duck and Rick. Do you have repair manual for it?

[ned37]

try the injector brain connector under the left side panel.  remove it and reseat it.

[K-Boom]

Gentlemen, I have beaten the demon on this K100 .............

I've followed all your advise and opened up the fuel-tank to find..........wait for it.......... the complete fuel pump floating around not secured with loose nuts and I suppose that is what caused the short that blew the fuses.

Thank You all so very much for assisting me !

Bobby :neener:

[mystic red]

Cool Bobby! Enjoy your new ride and post up some SA and bike pictures for us.

[K-Boom]

Will do so for sure

[mystic red]

While you're in there make sure all the rubber bits are in good condition. Ethanol treated fuel eats the rubber if left to sit for too long.

[Red]

 

Well done! ... I've been following your efforts to get your bike going all morning. I'm glad all is well again. You will really enjoy your K, I really like mine.  :2thumbup:

[DRxBMW]

Gentlemen, I have beaten the demon on this K100 .............

I've followed all your advise and opened up the fuel-tank to find..........wait for it.......... the complete fuel pump floating around not secured with loose nuts and I suppose that is what caused the short that blew the fuses.

Thank You all so very much for assisting me !

Bobby :neener:

You still may have to trace a short.

Congrats on getting this far.

Hang around motobricK long enough and you'll soon be a master K wrench.

[DRxBMW]

We need to know the year of your K100RS in order to help you.  If it's 89 or earlier then you should not hear the fuel pump until you press the starter button.

Thanks Drake, I assumed the 85 FP's were all the same.

Bobby, please ignore my stupid comment earlier about being able to hear the pump. LOL

[frankenduck]

Ethanol treated fuel eats the rubber if left to sit for too long.

It's not the ethanol.  It's water that gets in there that rots the rubber.

BMW issued a TSB that up to 10% ethanol is fine in K bikes.

[mystic red]

Ethanol treated fuel eats the rubber if left to sit for too long.

It's not the ethanol.  It's water that gets in there that rots the rubber.

BMW issued a TSB that up to 10% ethanol is fine in K bikes.

But ethanol treated fuel absorbs more water. It's the chicken or the egg. BMW states that ethanol treated fuel is OK but when it sits for an extended period.....then it rots the rubber. At least that's the way I take it.

http://www.fuel-testers.com/expiration_of_ethanol_gas.html

[frankenduck]

But if you ride fast enough then the water can't catch you and sneak into your tank.

[mystic red]

But if you ride fast enough then the water can't catch you and sneak into your tank.

You know that leaves me out then.