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Very Odd Cold Start Problem


woozer

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This happened this morning. After running perfectly for 8 months/4K miles (just serviced last week) it wouldn't start. Cranking and cranking, not even trying to fire. Nothing. So I took the other bike to work.
 
About five hours later I tried it again. This time it was sort of trying to fire, and feathering the throttle like an old dirt bike, I coaxed it to life. Off to the dealer we go.
 
They threw it on the probe and said the atmospheric pressure sensor and the sidestand switch had both generated fail codes. But each were functioning perfectly. They had no explanation other than to say that if it ever did it again to bring it back in (duh) and they'd dig deeper to find what might be causing it throw bogus codes.
 
In other news, it apparently keeps track of how many times you have stalled it. In my case, the number is four. It finked on me and told them this, which was a little embarrassing. But whatever.
 
Has anyone else had this happen? I would sure hate to have it happen anywhere other than my garage...
 
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It's common for my bike to turn over 5-6 times, then I let the start button go, then I hit it again to get it to fire. Not sure why it just doesn't fire the first time, and yes, I do turn the key and let the fuel pressure come up before I hit it. The electronics on this bike do make me nervous at times, I guess it's just something we'll have to get used to.
2015 FJ-09
2009 WR250R
1989 HawkGT
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The side stand code isn't anything to worry about. For some reason the ECU is quick to report that one as an occurred code, usually with multiple counts. Have yet to see it cause an actual problem.
 
The air pressure sensor could also have triggered during maintenance procedures (sync) or could be the issue
 
I would assume they cleared the codes. If so, and the starting problem returns- they will have a clearer picture of what's going on - esp if the Air pressure sensor code triggers again.
 
However, the ECU should default to a known value and still allow the engine to run, if it's a code for the Barometric pressure sensor, though I would need to check the Service manual to be sure.
 
Where it gets complicated is that the Intake air pressure sensor is also used by the ECU as a cam position sensor signal. If the line is kinked so the sensor is getting an intermittent drop in pressure, the engine would fail to start.
 
 
Hope that clarifies somewhat.
 
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Where it gets complicated is that the Intake air pressure sensor is also used by the ECU as a cam position sensor signal. If the line is kinked so the sensor is getting an intermittent drop in pressure, the engine would fail to start.
 
 
Hope that clarifies somewhat.
 
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This I do not understand. How can the ECU use this sensor to determine which cylinder is ready to fire? Is this sensor only reading pressure to a specific intake?

 
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Where it gets complicated is that the Intake air pressure sensor is also used by the ECU as a cam position sensor signal. If the line is kinked so the sensor is getting an intermittent drop in pressure, the engine would fail to start.  
 
Hope that clarifies somewhat.
 
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This I do not understand. How can the ECU use this sensor to determine which cylinder is ready to fire? Is this sensor only reading pressure to a specific intake?

 
 
Because the sensor recognizes a drop in pressure as the intake valve opens. The ECU already knows the position of the crankshaft/piston, so it then knows which cylinder is on the intake stroke. It fires the injectors and spark plugs accordingly.
 
The FJ/FZ engine has 2 intake air pressure sensors: the one connected to cyl 1 is used for cyl ID. Once it reads that cylinder is on the Intake stroke, the second and third cyl can be calculated.
 
Neat stuff.
 
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Because the sensor recognizes a drop in pressure as the intake valve opens. The ECU already knows the position of the crankshaft/piston, so it knows which cylinder is on the intake stroke. It then fires the injectors and spark plugs accordingly.
 
The FJ/FZ engine has 2 intake air pressure sensors for cyl ID. Once it reads those 2 cylinders, the third can be calculated also.
 
Neat stuff.
 
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Ahhh....I see

 
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  • 3 weeks later...
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This happened this morning. After running perfectly for 8 months/4K miles (just serviced last week) it wouldn't start. Cranking and cranking, not even trying to fire. Nothing. So I took the other bike to work. 
About five hours later I tried it again. This time it was sort of trying to fire, and feathering the throttle like an old dirt bike, I coaxed it to life. Off to the dealer we go....
 
 
Has anyone else had this happen? I would sure hate to have it happen anywhere other than my garage...

Same thing happened to me just before the holiday.  Pushed the starter, it started to start then almost immediately stalled.  Couldn't get it to crank.  I assumed a weak battery (getting colder and only riding it ~ 2.5 miles each day to work) so I threw it on a battery tender and drove to work.  Next day it took 4 or 5 times to finally get it to crank.  It was raining so I stopped and started it repeatedly with 0 problems.  I didn't see any codes when I checked on the display. 
We finally have good weather today so I'll try to take it out and see what happens.
 
I also need to go back and reread the other threads about engines suddenly dying.
 
My bike is 6 months old with ~ 4600 miles on it.
 
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I have two friends with FJs who have all reported varying degrees of the same hard starting situation.
 
Two things seem to make for a clean start:
 
1) As noted previously, wait until the fuel pump quits whirring.
2) Hold the starter button down until the motor is actually running.
 
A pal who's on his 5th R1 (he keeps wearing them out, go figure) concurs and says it's a Yamaha quirk.
 
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... 
1) As noted previously, wait until the fuel pump quits whirring.
2) Hold the starter button down until the motor is actually running.
 
...
 

(1) Always always do. 
(2) This could be it.  I thought the motor had caught and let go of the starter.  I've done that before with no problem, but it was a little colder this time.  Still disappointed that it took many, many tries (and a battery tender) to start it again after this problem.  As I said in my "Kawasaki" post, this bike is a little rough around the edges (and that's not a bad thing, but I like a bike to start). 
 
At least we can't experience carb icing like my old Kawasaki. :P
 
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For what its worth Super Teneres and FJRs also have a hard start problem although random and seldom. My Tenere did it once when new and has not done it again. With the Teneres owners figured out if the bike is run for a short period of time and doesn't get up to temp it can create a hard start on the next ride. Something confuses the ECU. For what its worth on the Tenere they figured out a sequence that seems to eliminate this problem. To start; ignition on kill switch off, let electronics cycle then start. In the case of a hard start wide open throttle seems to work. This is what seems to help on the Super Tenere it may or may not be the same on the FJ-09. After a Super Tenere caught fire and burned during a hard start this summer Yamaha admitted there is a software glitch and are supposedly coming out with an ECU update soon. Key thing to remember is it seems to seldom be an issue. My Super Tenere has never done it again so either the kill switch thing works or it is a rare occurrence.
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For what its worth Super Teneres and FJRs also have a hard start problem although random and seldom. My Tenere did it once when new and has not done it again. With the Teneres owners figured out if the bike is run for a short period of time and doesn't get up to temp it can create a hard start on the next ride. Something confuses the ECU. For what its worth on the Tenere they figured out a sequence that seems to eliminate this problem. To start; ignition on kill switch off, let electronics cycle then start. In the case of a hard start wide open throttle seems to work. This is what seems to help on the Super Tenere it may or may not be the same on the FJ-09. After a Super Tenere caught fire and burned during a hard start this summer Yamaha admitted there is a software glitch and are supposedly coming out with an ECU update soon. Key thing to remember is it seems to seldom be an issue. My Super Tenere has never done it again so either the kill switch thing works or it is a rare occurrence.
A former Super Tenere owner nods with the donkey (see what I did there :D  ) 
Also happened once on my Tracer. Wide open throttle sorted it and not seen again. I put it down to, "it's a Yamaha, it happens, don't stress, just WFO the throttle". 
This signature is left blank as the poster writes enough pretentious bollocks as it is.
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Also happened once on my Tracer. Wide open throttle sorted it and not seen again. I put it down to, "it's a Yamaha, it happens, don't stress, just WFO the throttle". 
 
When in doubt, WFO? :)
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