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Discussion Starter #1
While heading home after work my LT just cut off on me without an explanation. Rather than going through the story of that night, I will list all steps done in an attempt to resolve:
1. check fuel level - about a half tank
2. checked fuel quick disconnects - no leaks, solid connection
3. checked the fuses - not really sure which one is related to the fuel system, all fuses OK
4. check fuel lines inside tank for any blockage - fuel lines OK
5. checked power at fuel tank plug - no power with voltmeter when key turned on
6. stab in the dark, took the power leg for the accessory adapter and connected it to the fuel pump receptacle - fuel pump starts pumping.

With the results of #6, I assumed it was a bad relay.

7. Checked each relay (continuity - not sure how to do more than that concerning a relay). I found one relay to have different results than the others. Removed the cover to the relay to find one wire was broken. Headed to the BMW shop (Nashville). I was told the OEM (TYCO V23073-B1005-X18 black in color) relay was no longer carried and they cross referenced to another (SIEMENS V23073-B1005-X58 yellow in color).

8. Plugged in new relay, no change. UGH! When pushing the start button, It turns over without any problem. Sounds like she's not getting fuel.
9. Broke out the fox and hound (from the old telecom days) traced the wires from the fuel tank plug (green w/white stripe & brown) to the relays. The relay that was replaced appears to be the relay for the fuel pump. Unwrapped the the wiring bundle to verify. (what a mess!)

I am going to attempt to attach an image of the relay strip showing which one was replaced. Other than the steps listed, anyone have any ideas on what is wrong or what else I need to check?

I hate to have it towed to the BMW shop (about 60 miles away) to find out it was something simple. Any assistance is greatly appreciated. I haven't been able to ride and I am going through major withdrawals.

Bob
 

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Wrencher Extraordinaire
2005 K1200LT
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The relay only turns on to pressurize the fuel rail when the key is turned on, then it turns off. It stays off until the engine starts. Put your meter on the plug and turn on the key. I you get juice for a few seconds the relay is working. Time to look else where. Often the hose pops off of the pump inside the tank.
 

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Discussion Starter #3
John,

Thanks for the reply, I think I retested the voltage at the fuel pump receptacle after swapping out the relay. I am pretty sure I did but I don't have it in my log. I will check again to make sure.

All hoses are connected and where they are supposed to be.

Bob
 

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Just to clarify what John said....when you turn the key on you get voltage to the pump for just a second then none. If you hold the starter turning over you should get constant 12V as it turns over.

Ron
 

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2005 K1200LT
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bsellers said:
John,


All hoses are connected and where they are supposed to be.

Bob
Even Inside the tank? The fuel filter is inside the tank and sometimes the hose pops off. Also the loop hose has been known to spring a leak with age.
 

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Discussion Starter #6
Sorry to leave you guys hanging... Teenager issues sort of trumped the working on the scooter the past couple of weeks. I am spending today verifying all is where it should be and that it's connected properly.

I will reply as to the results.

Thanks,
Bob
 

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Turn the ignition key to "on" and then toggle the engine kill switch from off to on. The fuel pump should spool up when you do this. If not, then I believe you are on the right track. Tracing that kill switch circuit might be worth looking at too.
 

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Discussion Starter #8
No juice while metering the connection and just turning on the key. When the engine kill switch is moved back and forth, I do get a reading of 12.4 then 12.3 then 0. So, you are on to something!

I am going to remove the pump from the tank and see if I can get the pump to react as the voltmeter did.

Bob
 

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Discussion Starter #9
Now I am really confused (which is not surprising). After working the kill switch a couple of times, I get a power reading when I turn the ignition on. ?????

So maybe I have a kill switch circuit problem?
 

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The kill switch cuts off power to the fuel pump. I do not know if this is direct or indirect (relay or Motronic). So with the kill switch in the run position you should see power at the fuel pump connection for 1 or 2 seconds when you switch on the ignition. With the kill switch off you should see nothing and then 12+ volts for 1 or 2 seconds when you switch it to on. If you have power at the harness and the pump is not running then it's likely a bad ground (brown wire) or you need a new pump. It could also be the fuel rail pressure diaphram switch but I do not know how it is wired into the pump. If the pump grounds through the diaphram switch for control that would be a possibility as well but I do not know if it is wired directly in series with the pump.
 

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2005 K1200LT
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Actually the kill switch cuts power to the emergency shut off relay. This relay provides power to the engine electronics relay and the motronic controlls the ground to the fuel pump relay. So there is more than just one relay involved. The fuel pump relay always has switched power to it and the on - off cycle is controlled by the motronic by providing the ground signal to turn it on.
 

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Discussion Starter #12
Over the past couple of months I have checked, checked and double checked fuses, relays and connections. I went as far as tracing wires in the harness with a "fox and hound" device. This morning I get up with intentions to work all day if needed to identify why she's not running and flip the kill switch back and forth a couple of times and she fires right up.

Of course I started a list of steps in the past to refer back to as I worked towards a resolution. Today, I did not. So I am not sure as to what was done to solve the problem. I am spending some time tomorrow reviewing the kill switch circuit to ensure I don't have an issue there.

As usual, a little patience, attention to detail and of course the good folks of the BMWLT.com forum, my scooter is running again. THANK YOU!
 

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Bob,

I am having the same issue as you did in this post. Did you have the handlebars apart (on right side)? I did and am wondering if my kill switch got disconnected. I swear, reading your post is like reliving my nightmare with this same problem. Thanks for the prior work!

Jerry

Over the past couple of months I have checked, checked and double checked fuses, relays and connections. I went as far as tracing wires in the harness with a "fox and hound" device. This morning I get up with intentions to work all day if needed to identify why she's not running and flip the kill switch back and forth a couple of times and she fires right up.

Of course I started a list of steps in the past to refer back to as I worked towards a resolution. Today, I did not. So I am not sure as to what was done to solve the problem. I am spending some time tomorrow reviewing the kill switch circuit to ensure I don't have an issue there.

As usual, a little patience, attention to detail and of course the good folks of the BMWLT.com forum, my scooter is running again. THANK YOU!
 
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