i tried to start the bike & the battery was low, then even though i turned the key & the emergency shut down off,  the starter & engine turned weakly continuously about 4 times b4 the battery completely fell.
i got a new batt but when i tried to connect it, the starter & engine turns even though key is off.
to take off tank so pulled off the electrical cable to the fuel pump, i then connected the batt but this time the starter didn't turn until i turned on the ignition. reconnected the electrical cable to fuel pump & tried to start, the starter & engine turns but the engine doesn't start. i tested 1 spark plug & its ok but still the starter & engine turns but engine doesn't start.
help!!! please

check the rest of the fuses first

the fuses are ok

can you hear the pump running ?  (should run for about 1.5 seconds after the start button is pressed ..)

Open the gas cap and then turn on the ignition.  Listen for the pump It won't run a lot, as it only has to pressurize the system.   if the pump doesn't make a sound, then either the connector is not completely connected or the pump bit the big one. 


If it tires to start without the ignition being on, you may have welded the relay.  List tank and locate the starter relay (back edge of relay box with thick wires.  Tap/whap it with the back of a screwdriver that will generally free the relay contacts.

Could have flooded it if the pump runs.  Wait about 20 minutes and try it again

i hear the whining sound of the pump,
about to check the relay

Relay is welded, happens trying to start with a weak battery, lots of posts on it. You can open it up and sort it or get a replacement. Keith has it picked up and you need to do as he said. Hopefully that will sort it.

the relay & everything in the box is fine, the wires too are fine

i got a new batt but when i tried to connect it, the starter & engine turns even though key is off.

As far as I know this happens when the relay is welded.

Relay may "look fine" but if the starter turns with the key off or out, then the relay is welded. Disconnect the battery, lift the tank , remove the outer cover and rap it a good one. Reconnect and see if it still tries to start when off.

You can remove the outer cover of the relay and have a look at the contacts they have welded together due to high current.  Sometimes they can be pried apart but not always.
The relay is in the back right corner of the relay box under the rear of the tank. It has 2 thick cables and a small push on connector.

the relay is fine, the starter no longer turns when i connect the batt but the engine cranks but never starts, that's the problem now. i tested 1 of the plucks but its good. even this morning, the starter turns and engine cranks but never starts, I've check electrical connections but it still doesn't start. please help

Check the connection of the EFI computer (computer seating on the top of the battery).

Your post doesnt say what year your K is.

If its an early one there is a plastic 4 pin connector at the front of the fuel tank, left side. Just check it is a tight push fit so that the electrical connections are good. If it comes off very easily then it may not be making a good electrical connection. If there is a problem with his connection the engine will turn over but not fire because no fuel. You will hear the fuel pump relay click but the current doesn't reach the pump. You can open up the pins very slightly to improve the connection and fit.

I'll check the connections under the tank to the pump and the EFI.
I must say that there's fuel in the hoses and rail: in fact I tried to loosen the clip of a hose on the rail & fuel gushed out.
nevertheless I'll check the connections as suggested

When you say gushed out was it under pressure? If the connection is erratic, which is possible, it will stay under pressure for a while. If you open the connection immediately after the engine has cut out you will still get a gravity flow.

I have had the same problem and the cause was that 4 way connector.

The pump should run for 1.5 seconds when you tap the start button does yours do that?

it's the 4-way connector to the pump on the tank, thanks a lot guys.
1 more thing, i wonder if my alternator works fine: when i started the bike, the batt light came on and remained on even though the engine was idling. when i raise the rev, it goes off but comes on as i allow it to fall back to idle?

You have to rev the engine to get the alternator/battery light to go out. But if its coming back on when you let the engine idle with lights off doesn't sound right. It will glow a bit at idle with lights on.

so might it be the battery ain't charged or the alternator. nevertheless, after revving it a bit, the light stayed off at idle

You should be ok, but just check out why the battery was down. It can happen just by leaving the bike parked up for a long time.

But if you ever find the battery low and the starter is struggling don't keep trying it. It actually draws a lot more current through the realy and welds it.

The forum is about sorting things too so glad you are sorted. Go and enjoy a few miles on the K to charge the battery.

You have checked the starter relay but try the load shed relay, smaller one towards the front of the electrical box under the tank,

you may have welded the contacts, I did the same as you not so long ago, starter relay OK, swapped out the load shed and all fine.

If your alternator charge light is staying on past idle then the alternator probably needs new brushes.
You would probably be best off to get a complete new regulator/brush combination as the regulator tends to get a bit tired over time. It's easy to replace them just 2 screws on the alternator and you don't need to take the alternator off the bike even. Don't buy a genuine BMW item from a dealer get a genuine Bosch from almost any auto electrician or auto store for around $30

thanks. but my alternator light doesn't stay on past idle, it comes on once the engine falls back to idle.
another thing, its almost impossible to get parts in my country, Ghana-West Africa.

Does the alternator light stay on bright at idle? At night mine will glow bright enough with lights on and when braking but it does keep the battery fully charged. Do you have a meter to check it? If you don't and if its keeping the battery charged then you should be ok.

emmanuelfiadjoe wrote:thanks. but my alternator light doesn't stay on past idle, it comes on once the engine falls back to idle.
another thing, its almost impossible to get parts in my country, Ghana-West Africa.

The idle speed is 900-1000rpm so it may be idling a bit slow or if that is OK then it usually is a sign the brushes are well worn so it may be worth ordering some new brushes now to save the wait. Usually I just change the regulator which includes the brushes but brushes can be bought separately and soldered in.
Motobins in UK have them http://www.motobins.co.uk/bmw-parts.php?model=K%20Series but most likely would be available from auto electricians as they are a common size.
Motobins in UK would probably be your best place to buy parts.

I have a meter, how do I check the alternator?

Rick, I think it idles a bit slower when i start it first but when the revs up about 900-1000, the alternator lights do go out.

is it normal that while i start the engine cold without revving it, it runs shortly and then goes off? this doesn't happen when its warm.

The black or negative lead to the negative of the battery and red to positive of the battery. Start the bike and at idle the meter should read close to 12.6 volts increase the revs to 1500rpm and the voltage should go to at least 13volts and at 2000-2500 the reading should be close to 14 volts.  13.8 is acceptable and 14.2 is really good.

This is a good post to read it gives the amateur a better understanding of using electrical testing gear
https://www.k100-forum.com/t264-testing-electrical-systems-with-a-digital-multimeter?highlight=using+a+multimeter

thanks rick

the link in that post takes you to a different page i think, where can i get the hard copy

It could be that Rick did have the following page in mind, but linked to the wrong one.

https://www.k100-forum.com/t725-using-a-test-meter-volts-amps-and-ohms

Thanks Inge I have never even looked at that as I am very conversant with meters etc