Sudden death

[Zorman]

It has happened to me 2x in a row now. I am riding my bike and over sudden it just dies. I pull over and it starts up, sometimes  it's hard to start it again though. Once it starts it runs fine.

any suggestions?

cheers

'85, K100

[frankenduck]

Like suspects:

Fuel tank connector

Ignition switch

[Rick G]

More often it's the fuel pump than anything else. When it stops try turning the kill switch of and when you turn it on the pump should run for 1.5 seconds then stop, if this does not happen the pump is the likely culprit but take it out and test it futher.
Check out the lieberry card index here to find a thread about fuel pumps. Our high priest here (frankenduck) has many notes about them, also I think how to do a chicken bone dance to exorcise the demons from the bike.

[frankenduck]

When it stops try turning the kill switch of and when you turn it on the pump should run for 1.5 seconds then stop, if this does not happen the pump is the likely culprit but take it out and test it futher.

The fuel pump on K75s and K100s only runs when the engine is turning.  Only the 4V Ks pre-pressurize  the fuel system.

[Rick G]

When it stops try turning the kill switch of and when you turn it on the pump should run for 1.5 seconds then stop, if this does not happen the pump is the likely culprit but take it out and test it futher.

The fuel pump on K75s and K100s only runs when the engine is turning.  Only the 4V Ks pre-pressurize  the fuel system.

My appologies you need to touch the starter button to get the pump to run for the 1.5 second

[BrickFlyer]

The 85 K100 had a really touchy fuel pump connector.  Remove the left hand side fairing cover and you'll see it. It connects the fuel pump and fuel level sender and if it wiggles loose you'll lose the fuel pump and the engine will cut off. See picture below.  The symptom is totally random and can happen 5 minutes or 2 hrs into a ride. You can also sometimes just get a hesitation, like when you're doing 70 mph and all of the sudden it feels like you totally cut the throttle. Then it will restart before you slow to 50 mph and launch you like a bucking horse and run like nothing ever happened.

The same things can happen if your EFI brain connector is not fully seated, or if your Hall Effect Sensor is going bad. If it is the Hall sensor, the cutoff will usually occur only when the engine is heated up. Then it will be hard, if not impossible to restart the engine until it totally cools down.

Make sure the fuel pump connector and EFI brain are solidly connected. They can look good, but all it takes is a little wiggle and you're hosed.  If it is you Hall sensor you'll have to replace it. Not a cheap item.  Can run close to $300 or maybe you can go with used on Ebay for $100. Easy replaceent if required.

[Zorman]

The 85 K100 had a really touchy fuel pump connector.  Remove the left hand side fairing cover and you'll see it. It connects the fuel pump and fuel level sender and if it wiggles loose you'll lose the fuel pump and the engine will cut off. See picture below.  The symptom is totally random and can happen 5 minutes or 2 hrs into a ride. You can also sometimes just get a hesitation, like when you're doing 70 mph and all of the sudden it feels like you totally cut the throttle. Then it will restart before you slow to 50 mph and launch you like a bucking horse and run like nothing ever happened.

I suspect it's the connector. Would spraying lithium grease inside the female end would fix this?

[frankenduck]

If you want something reliable then replace it with a different connector.  The terminals get loose in the connector housing.

[Zorman]

If you want something reliable then replace it with a different connector.  The terminals get loose in the connector housing.

No question, where would I find such a connector?  BMW doesn't sell just the connector.

[robleyd]

Pretty much any car spares place should carry a generic four pin connector. These are available this part of the world - http://www.narva.com.au/products/browse/specialised-connectors - and I'm sure there a load of places on your side of the world :-)

[motodude]

Frankenduck has used (http://www.motobrick.com/index.php/topic,879.msg3428.html#msg3428) a four-pin flat trailer connector.  I've used the same thing with good results.

Tom

[motodude]

And, dielectric grease is an insulator, not a conductor.  It is used primarily to keep the environment out of electrical connections.

Tom

[frankenduck]

And, dielectric grease is an insulator, not a conductor.  It is used primarily to keep the environment out of electrical connections.

Tom

Excellent point.  I wouldn't necessarily call it an insulator but it's certainly not conductive.  Just like WD-40, it's main attribute is that it deters corrosion.

[motodude]

And, dielectric grease is an insulator, not a conductor.  It is used primarily to keep the environment out of electrical connections.

Tom

Excellent point.  I wouldn't necessarily call it an insulator but it's certainly not conductive.  Just like WD-40, it's main attribute is that it deters corrosion.

Yes, of course.  It is not used to _insulate_ but to protect.  I just hear/read all too often of folks using dielectric/lithium grease to restore connectivity.  It won't do that.

The trailer connector is a gem of an idea.  It is robust and it fits between the rear of the tank and the under-seat glove-box nicely too.

Tom

[Zorman]

Pretty much any car spares place should carry a generic four pin connector. These are available this part of the world - http://www.narva.com.au/products/browse/specialised-connectors - and I'm sure there a load of places on your side of the world :-)

I am sorry if this is obvious to you all... but I am kinda stuck with the male end of the connector as it is part of the fuel pump isn't it?
And the female end needs to sink into a cylindrical socket.  :hmm:

[Opus]

@ Rick G.

Dude, everyone knows that you use " Chicken Blood Vodoo" to fix Microsoft & Mac OS Problems.
To fix a problem with a bike you have to deflower a virgin on bike night!


Opus!  :hehehe

[kennybobby]

the male end of the connector as it is part of the fuel pump isn't it?

It looks like you have a broken male pin in that connector?

[Inge K.]

I am sorry if this is obvious to you all... but I am kinda stuck with the male end of the connector as it is part of the fuel pump isn't it?
And the female end needs to sink into a cylindrical socket.  :hmm:

Earlier suggestions about changing out the connector is valid on -86. on models, which have a pigtail connector.

Inge K.

[mystic red]

So Inge, what would you do to fix the flaky connector on his 86? Or does he have to replace the fuel pump?

[motodude]

I am sorry if this is obvious to you all... but I am kinda stuck with the male end of the connector as it is part of the fuel pump isn't it?
And the female end needs to sink into a cylindrical socket.  :hmm:

Earlier suggestions about changing out the connector is valid on -86. on models, which have a pigtail connector.

Inge K.

Yes, I did not realize that this was an '85 nor did I know their connector was so different.  My apologies for the confusion.

Tom

[Inge K.]

So Inge, what would you do to fix the flaky connector on his 86? Or does he have to replace the fuel pump?

Sometimes pictures wiewed on the computer could be quite different from as seen with your own eyes in the real world, but those male connector pins looks far from clean to me........and if the female is in the same condition.................search DeOxit.

The fuel pump is a separate unit, the connector is combined with the level sensor as one unit.

Inge K.

[mystic red]

If you want to check your ignition switch (someone correct me if I'm wrong) turn it on and check the voltage at the fuses. Less than 12 volts and you've got your problem. Ignition switch will cause you're symptoms.

[frankenduck]

If you want to check your ignition switch (someone correct me if I'm wrong) turn it on and check the voltage at the fuses. Less than 12 volts and you've got your problem. Ignition switch will cause you're symptoms.

You're wrong. :ba:

Only 1, 2 & 6 are switched.

First key position - 2 only for the parking and tail lights

[mystic red]

Yea, that's why I thru in the disclaimer. Should have said "check voltage at #1 fuse.

Decreased voltage there is an indication of a faulty ignition switch."

[Inge K.]

Decreased voltage there is an indication of a faulty ignition switch."

Or kill switch.................