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Discussion Starter #1
Where is the fuel pump relay located? I see plenty of pictures of it online but I can't tell exactly what all it is under. I removed the left side panel and only see gas tank. So am I looking in the right area and just need to remove the tank now/under that?

The long story of this is: was on a ride, stopped to talk and decide where we were going, and bike wouldn't start up again. Just cranks and cranks but no go. I never hear the fuel pump prime. Took the right panel off and checked for the quick disconnect issue and it has already been fixed. Jumpered the fuel pump manually and it comes on fine so don't think it be stuck. And never see power making it to the fuel pump. So my guess is relay..... I'm just having trouble finding it. Such a nice day today I want to get this baby going!!
 

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Wrencher Extraordinaire
2005 K1200LT
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OK Not a common failure. Most likely it is a loose or damaged hoses inside the fuel tank. When you turn on the key the pump only runs for a second or so and is hard to hear with the ABS cycling at key on. Better way is turn on the key and let the bike get quiet then cycle the kill switch. Every time you cycle the kill switch the pump will run for a second or so. If you can jumper the pump with 12 volts (don't use the extra accessory plug - it fits but is wired backwards) the bike will run if the relay is the issue.

The relay is located in the electrical box under the tank.
 

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Welcome to the forum cashman

Fuel pump relay is under the tank on the right side. There are many that can replace this from any auto parts store but be aware that they must have a resistor and not a diode inside as on the LT, the polarity would be forward biassed for a diode and it will short and burn up. Ask me how I know this?


The fuse to check for blown or power present is fuse #4 in box 1 of 3 15A if you have an 05 or older. Fuse 11 box 2 10A has only 2 fuse boxes for 06 and newer. Should be always hot at the box.
 

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Discussion Starter #4 (Edited)
So I got the tank off and found it. When I had tested before I never heard the pump run at all, and my abs doesn't run on this bike so no noise from it drowning it out. But now that I have the tank out I will pull the fuel pump and check the hoses to see if any came loose. While I have it apart I'm going to replace the relay to try it either way. Does anyone have a replacement part number that works or link to amazon or similar where I can order?

EDIT:

Well, I tested the horn and then swapped it with the fuel pump relay and tested again and still worked. So guessing not relay. I also pulled the fuel pump out and no hoses are disconnected. I had checked the fuses originally and none were bad. So now I'm at a loss on what to try next.

EDIT #2:

Ok....now I don't know what to think. For the hell of it while the tank was off I decided to test the voltage on the fuel pump again and now I am seeing it after turning the key on. So either I was doing it wrong before, or I don't know what. I'm going to take the fuel pump off again and make sure to tighten all the clamps down, then put it back on and try it and see what happens.
 

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So I got the tank off and found it. When I had tested before I never heard the pump run at all, and my abs doesn't run on this bike so no noise from it drowning it out. But now that I have the tank out I will pull the fuel pump and check the hoses to see if any came loose. While I have it apart I'm going to replace the relay to try it either way. Does anyone have a replacement part number that works or link to amazon or similar where I can order?

EDIT:

Well, I tested the horn and then swapped it with the fuel pump relay and tested again and still worked. So guessing not relay. I also pulled the fuel pump out and no hoses are disconnected. I had checked the fuses originally and none were bad. So now I'm at a loss on what to try next.

EDIT #2:

Ok....now I don't know what to think. For the hell of it while the tank was off I decided to test the voltage on the fuel pump again and now I am seeing it after turning the key on. So either I was doing it wrong before, or I don't know what. I'm going to take the fuel pump off again and make sure to tighten all the clamps down, then put it back on and try it and see what happens.
That is the worst kind of problem. One that seems to correct itself. If I were you, I would leave the horn and fuel pump relays swapped and see if you have any future issue with your horn :)

Also you haven't stated your year yet so those inside tank lines may be getting close to a failure from Ethanol poisoning. Several options now exist to replace them. the Euro MotoElectric nylon lines as well as after market molded rubber lines plus the dealer OEM molded lines at the usual premium.
 

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Discussion Starter #6
I put the tank back on and did the following: Hooked it all back up and tried to start, didn't work. Checked power to fuel pump, no power. Manually jumped the fuel pump to 12v: bike started. Shut down. Checked power to fuel pump, and power. Hooked up, no prime, no run. Manually jumped it again, didn't start that time. Checked power to fuel pump, no power.

So I'm at a bit of a loss. My problems seem to be: 1. Intermittent power to the fuel pump. 2. Starts and runs intermittently when manually powering the fuel pump.

Anyone have any thoughts on what to try next?

Also, I did leave the horn and fuel pump relays swapped.
 

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When you manually jumped it the second time, was the pump running full time when it didn't start?

I am also going to guess that you have an 01 or earlier US if your ABS is not running and you are still riding it.
 

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Do you have an anti theft system on it? Not sure it was available on your year which we don't know yet.
 

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Discussion Starter #9
I have a 2001. Sorry. Kept forgetting to say. And no anti theft system. And the second time I jumped it I had pump running the whole time I was trying to start it. Small chance I completely drained the tank of gas so have to try to add some. But at this point with the intermittent fuel pump power would I be right in thinking that it might be the motronic computer?
 

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The signal to engage the pump relay is pin 16 on the motronic. Looks like a blue with a brown stripe on the schematic. If you get the prime voltage there and it picks up when cranking, that would also say the hall sensors are working as it needs to sense those ( engine rotating) for the pump to start after the prime and keep running. I would make sure you have 12v at the relay plug and possibly try and measure from the pump plug back to the relay plug and make sure you have good continuity. The pump relay also powers the injectors so if you power the pump aside from the plug, the injectors won't fire if the system is not powering that circuit. If you had it running and then powered it again the same way and it didn't run, I would be tracing wires back to see where the issue is, possibly a loose plug or chafed wire? Of course, if the tank had no gas in it then fix that first :)
 

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Just out of curiosity what are the wire colors on the connector hooked up from the bike to the fuel pump? Is is Red/Yellow and Brown or Green/White and Brown.
 

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Discussion Starter #13
The signal to engage the pump relay is pin 16 on the motronic. Looks like a blue with a brown stripe on the schematic. If you get the prime voltage there and it picks up when cranking, that would also say the hall sensors are working as it needs to sense those ( engine rotating) for the pump to start after the prime and keep running. I would make sure you have 12v at the relay plug and possibly try and measure from the pump plug back to the relay plug and make sure you have good continuity. The pump relay also powers the injectors so if you power the pump aside from the plug, the injectors won't fire if the system is not powering that circuit. If you had it running and then powered it again the same way and it didn't run, I would be tracing wires back to see where the issue is, possibly a loose plug or chafed wire? Of course, if the tank had no gas in it then fix that first :)
I'll check later on the pin 16 and see if I can get repeatable results on the pump prime. It would be nice if that was the case and I just had a bad wire somewhere along the way.
 

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I'll check later on the pin 16 and see if I can get repeatable results on the pump prime. It would be nice if that was the case and I just had a bad wire somewhere along the way.
I think the motronic actually grounds the connection to close the relay so there would be 12v on pin 16 when the relay is open and maybe some lesser voltage closer to a ground reference when closed. I hope someone can confirm that the motronic is not the source of the 12v but the ground reference to close it.
 

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Yes the motronic provides the ground for the relay and for the fuel injectors (different pin).
 
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