Posts
365
Joined
12/24/2011
Location
CA
US
Temor a la Mancha
3/8/2012 5:20pm
3/8/2012 5:20pm
Edited Date/Time
5/31/2016 7:24am
Ok KX experts... I have a major head scratcher. I have a 2011 KX450 with 29 hours. The valves are in perfect spec. It fires right up when cold, but as soon as it reaches operating temperature, it will NOT start. I kick and kick and kick and it won't start. I've checked stator resistance and it's in spec. I took it to a dealer to have them check the FI for error codes and it showed nothing. Like I said, the bike starts right up just fine when it's cold, but as soon as it reaches a certain temperature, it will not start.
I've double checked the valves and they are perfect. It's either an electrical or fuel problem, I just have no idea how to narrow it down. Hoping someone else may have had this issue with a FI KX450. Starts fine cold, won't start when hot? Why the hell not?! I'm at my wits end. I don't know where to go from here other than disconnect everything and reconnect. I do have a remapped ECU, but it's been remapped since 5 hours and ran perfectly fine up until 24 hours or so. When the bike is started it runs perfectly fine. Doesn't cut out, perfectly crisp throttle, but as soon as I shut it off, it will not start again.
I would buy someone the hottest stripper in the land if they can help me diagnose this problem.
As a side note: one other new issue I've also noticed is that when I disconnect the fuel pump from the bike, it leaks right at the little black tube that comes off the fuel pump. It never did this before. It's almost as if there's a valve or something messed up in the fuel pump. This is giving me cause to believe perhaps the bike is getting too rich? I don't even know if that makes sense, but fuel shouldn't be flowing out of the pump unless it's running.
I've double checked the valves and they are perfect. It's either an electrical or fuel problem, I just have no idea how to narrow it down. Hoping someone else may have had this issue with a FI KX450. Starts fine cold, won't start when hot? Why the hell not?! I'm at my wits end. I don't know where to go from here other than disconnect everything and reconnect. I do have a remapped ECU, but it's been remapped since 5 hours and ran perfectly fine up until 24 hours or so. When the bike is started it runs perfectly fine. Doesn't cut out, perfectly crisp throttle, but as soon as I shut it off, it will not start again.
I would buy someone the hottest stripper in the land if they can help me diagnose this problem.
As a side note: one other new issue I've also noticed is that when I disconnect the fuel pump from the bike, it leaks right at the little black tube that comes off the fuel pump. It never did this before. It's almost as if there's a valve or something messed up in the fuel pump. This is giving me cause to believe perhaps the bike is getting too rich? I don't even know if that makes sense, but fuel shouldn't be flowing out of the pump unless it's running.
I'm going to go through all the connectors tonight, make sure nothing is loose, use dielectric grease and go from there. Frustrating.
i know your bike is fuel injected - do the EFI bikes have "hot starts"? just out of curiosity. I have the same issue with 15-20 minute rides. My bitch gets hot hot hot. then doesn't want to start for a little bit after that.
Good luck dude.
The Shop
Your flashed ECU may be too rich for hot starting. When the engine is hot, it needs more air.
The ECU mapping I have now is straight from the Kawi off-road team and it's actually a bit leaner so I run (usually) a 50/50 mix of 110 and 91, but sometimes a bit heavier on the 110. If I don't run race gas, it can detonate under a heavy load. I do want to reflash it, perhaps going back to stock or maybe one of the mappings Precision Concepts has for their off-road race bikes. I want to be able to go to Baja and not worry about running high octane gas.
I did remove the fuel pump awhile back and partially disassembled it (i.e. removed the outer rubber bladder and pulled off the fuel filter). It seemed relatively harmless and straightforward. I took it apart because I run a dry break and thought I might have introduced a small amount of dirt from the dump can. It was perfectly clean and void of any dirt particles. It went together just fine. The weeping is obviously not right, which leads me to believe it may be a fuel pump issue. I probably shouldn't have touched it.
It's just weird that the temperature is a factor. I can't quite pinpoint why that would be the case and how that would affect the fuel pump other than creating a super rich condition, like you suggested.
It only has 29 hours on the motor, but good god, do I have a leaky valve or is there something electrical happening between the kickstarter and the fuel pump?
Thanks for the tips. Much appreciated.
@Haven024 same goes for you, check your temp censor.
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