2 parter...Won't idle once warm and now won't start - K-Bikes.com - Excellence in Motion
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post #1 of 9 (permalink) Old Jan 16th, 2020, 12:00 am Thread Starter
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Question 2 parter...Won't idle once warm and now won't start

Hello All,
I'm hoping someone here can shed some light on my issue(s).

To begin, I have a 2009 K1300S. A few years ago I spun a bearing. The bike had about 47K at the time of death. After some research, I found that it was not practical to replace the bearings and shaft. I found a used engine from a 2010 with about 14Ks. I installed the new(er) engine.

Keep in mind, this was about 2-3 years ago...The bike started right up, but once the engine warmed up to operating temp, the bike would not idle and then stall. Once hot, you could get it started, but the bike would simply stall again. The only way you could keep it running was to give it gas and even if you did, it didn't sound or run like it did or should. The result was an unrideable bike. I put it on the back burner and purchased another bike for commuting purposes. I stored the bike outside, for the first summer it was uncovered and then covered up until now. Any ideas on why the engine will not idle once warm?

Now that I have extra time (and I miss the hell out of this bike), I decided to see if I could figure out the problem, but now I have a new issue. The engine will turn over, but will not start. I was able to get it to run on starter fluid, but the bike would die once the fluid was depleted. So, I know I'm getting spark. The culprit seems to be no fuel. I cannot hear the fuel pump prime, but honestly, I never noticed if it primed before. My feeling is that the pump died or corroded while sitting for so long. I want to test the pump, but I am not sure which wire is positive and ground. There are three wires as you may know. Can you tell me which wire is which? I can then apply 12V to see if its the pump or the signal coming from the canbus. I did take a meter to the three wires and detected about 3V on one wire coming from the harness.

Thank you in advance!
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post #2 of 9 (permalink) Old Jan 16th, 2020, 2:12 am
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Same pump like in the video...

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post #3 of 9 (permalink) Old Jan 16th, 2020, 8:40 am Thread Starter
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Originally Posted by Patrique83 View Post
Same pump like in the video...

Thanks! I'll give this a try today. I will just make my own leads and test off the battery.
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post #4 of 9 (permalink) Old Jan 16th, 2020, 2:53 pm Thread Starter
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Thumbs down

I tested the fuel pump by removing the controller and putting voltage directly to the pump. All I heard was a quick bump, but no spinning. I tried reversing the polarity as well with the same result. Each time the wires got very hot. It sounds like the pump is seized. I'll replace then report. It sucks to have to take a step backwards. My main problem is the idle issue. I hope to get back to that soon.
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post #5 of 9 (permalink) Old Jan 16th, 2020, 4:48 pm
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Originally Posted by mkoch View Post
My main problem is the idle issue. I hope to get back to that soon.
Sounds like the pump is your idle issue.
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post #6 of 9 (permalink) Old Jan 16th, 2020, 6:13 pm
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I agree the pump seems to be your present problem, but probably not the only one, so fix the pump and report. You also need to know that after long storage, there's good gas in there.

A long-stored engine could have rodent infestation that blocks airflow, or some little booger gnawed a great horrible hole in the intake tract. Since the bikes don't use manifold vacuum as an ECU input, it's unclear whether an intake leak would cause a starting problem. Running issue, probably, since more air would enter than indicated by the throttle position sensor, and the bike would stall lean.

I'm may be a little out of my depth but: an engine starts on a preset rich mixture and is then controlled by the ECU according to information received from sensors. That it may not idle could be caused by several things.

Verify adequate fuel delivery (pressure and volume) but since there is no fuel filter there should be no restrictions downstream of a properly working (on/off) pump. The pump is not "controlled" by the ECU, other than on/off.

The fuel rail and injectors should see constant pressure, monitored by the fuel pressure sensor on the fuel rail. The sensor could be off, telling the ECU that the pressure was high (mixture is rich) so the ECU compensates by shortening the injection pulse width/duration, resulting in lean stall. If you have a GS-911 it will tell you the fuel pressure as reported by the sensor, as if the pressure sensor is correct, which latter may not be. My fuel pressure sensor showed a constant incorrect value at about 42 psi (converted from whatever the GS-911 readout was, and they don't tell you the units, damn their eyes).

OR, as I found to my expensive dismay, the fuel pressure sensor could report low, resulting in longer injector pulses and a very rich/barely running engine. This does not seem to be your problem, I only mention it to illustrate that when the sensor takes a shit, the bike may run very rich if at all.

BMW cars with slowly failing crank sensors (they report rpm to ECU) show resistance values out of spec, but I don't know the bike sensor resistance spec. Perhaps someone will chime in. It might be the same or not much different from the car sensor values, I dunno.

Please post the diagnostic approach, results and solution for your bike. There's a real dearth of tech info how the bike is supposed to run, and each found solution can enrich the rest of us.

Last edited by Honolulu; Jan 16th, 2020 at 6:20 pm.
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post #7 of 9 (permalink) Old Jan 17th, 2020, 5:37 pm Thread Starter
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Thanks Honolulu. I can confirm there isn't any pest damage. The idle issue was my initial problem right after I changed the engine a few years ago. The pump should be here on Monday (1/20). I should be able to at least reproduce the initial issue at that point. I'll keep the thread posted. I'm also filming this process on my Youtube channel. I'll post the link with the pump install once completed.
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post #8 of 9 (permalink) Old Jan 25th, 2020, 3:59 pm Thread Starter
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Talking All Fixed!!

Well, good news. I changed the fuel pump and the bike started right up! However, I still had my initial issue idle and all-around poor performance. I did a pressure smoke test to rule out vacuum leaks. I found none. I then went back to square one and pulled the air box. From there I double-checked my electrical connections. It turned out that I had a knock sensor and idle air control valve crossed, basically all sorts of F**kery. I buttoned the airbox up and she started up and idled as she should. I'm so happy that's all working, but yes, feel stupid. I searched and searched for a wiring schematic but couldn't find one. The only picture I found that helped was a tutorial for an aftermarket fuel controller. There happened to be one picture with the color-coding that clued me in.

I documented the fuel pump replacement for our bikes here. It only cost me about $59.

Thanks for everyone's help!

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post #9 of 9 (permalink) Old Jan 26th, 2020, 9:23 am
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Glad you are sorted and the bike is happy once again!
Thanks for documenting the process too!
I know it will help several in the long term.

2014 Honda F6B "Isleen"
2008 BMW K1200S "Lena"
1995 HD Heritage Special "Saorla"

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