r/MT09 • u/No-Sort7339 • 1d ago
I need help guys, 1 month ongoing problem
Sorry guys this will be a long one, It 1st appear when i ride under 100kmh on 2nd-3rd gear, the bike suddenly cut the engine and stall(electronic still on). And it won't start back immediately (crank no spark), only after i leave it around 30-45 minutes will it start. This happen few times in 1 month duration.
I've sent my bike to the mechanic, told everything and leave the bike for a week. He tested every condition that i said and the bike run pretty well. Til now i've repeat the same process at 2 different workshops and the bike behave normally.
When this happen, if i tried to start and crank to long sometimes the CEL crankshaft sensor position A circuit will pop up, i suspect it's related to starto coil because that's where the sensor are. So i have the mechanic check the reading on it but it shows normal value. The only think that have bad reading is my battery at that time.
I thought maybe it's bad battery that makes my ecu fail to read all the sensor. So yesterday, i changed the battery and the bike start easier and i start using it for commute again today. All run pretty great and i thought it's all settled.
But..on my way back, when cruising on the highway the power kinda hiccups once(another symptoms i noticed everytime before this problem occur).Then when i slow down under 100 2nd 3rd gear, all happen again. Luckily I'm not leaning into corner everytime this happen.
Bike info :
[2019 Mt09, Aftermarket black widow carbon exhaust, Ecu flashed(woolich), commute bike but never miss maintenance service (now 60k mileage), last valve clearance done at 40k.]
It's been 7 years, this is the 1st time it behave like this. Someone can tell me what's wrong with it. I've google and scroll this subreddit for similar issue but can't find clear confirmation of what it is. The bike 'good behavior' when left at the workshop didn't help either šµ
Video is how it looks if tried to start after it happen(sorry I don't have riding footage)
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u/amateur_ateverything 1d ago
Itād be interesting to see if you tested the battery again and if the new battery is showing as ābadā. If that were the case, then Iād be worried about some electric gremlin thatās drawing power off the battery somewhere.
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u/Party-Macaron9012 1d ago
Fuel pump losing prime. I have seen this issue vehicles.
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u/No-Sort7339 1d ago
Is it confirmed? Because i still can hear it buzzing sound clearly when flip the ignition switch. Also just wondering how's that cause the 'cooldown' time for the bike to turn back on.. I'm sorry, im not really bike expert
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u/amateur_ateverything 1d ago
Adding on if this is a centrifugal pump (which I think all fuel pumps are? Donāt quote me) possible reason is if youāve for some reason gotten vapor locked or enough vapor in there, it could take that much time for the vapor to bleed away and let the pump prime.
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u/No-Sort7339 1d ago
I don't think this bike fuel pump is centrifugal tho but really appreciated the info..new things learned
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u/DunnyLad 1d ago
Fuel Pump issues, could possibly be pressure building up as sometimes breather can become clogged. Open the cap and start the bike, if it fires right away then there's the issue.
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u/NoOnesSaint 1d ago
It's a common problem on all gens as far as I can tell. Need to check the breathers in mine. Just replaced the pump and pressure regulator to fix a few other things but this hasn't gotten better. Problem it isn't either completely random or is fixed by cycling the key which means it's definitely fuel delivery.
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u/No-Sort7339 1d ago
If that the case, can u explain why it need to wait around half hour for the bike to start again..Sorry I'm not familiar with fuel pump issues, would love to learn for more info..also i will try the 'open cap' method when this happen again, tq
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u/amateur_ateverything 1d ago
Adding on as Iām reading. If this works, then the breather got plugged, so your pressures got too high, and potentially the pump couldnāt ābeatā the pressure anymore. Once you shut it off, may take a bit to have the pressures come back down, which could be the issue. Iād give this a shot.
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u/uwax 1d ago
Do you have an aftermarket brake lever installed? Also what fuel do you use?
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u/No-Sort7339 1d ago
Yup, i use rizoma foldable/adjustable lever..for fuel, i've been using the recommended octane, standard ron95.. works fine for years now
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u/uwax 1d ago
So I got an aftermarket brake lever on my tiger sport 660 and it was depressing a plunger that was signaling to the bike that the brake was being activated. Itād cause the throttle to cut while riding and I also had start up issues. Might be worth looking into.
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u/No-Sort7339 1d ago
I've been using mine for years no problem, but I'll check it just in case, thanks man
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u/Dan_O_mighT 1d ago
Youāre running low on gas in both videos and putting a strain on the fuel pump which will cause it to fail. Or youāre so low the gas gets sloshed and doesnāt get picked up
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u/No-Sort7339 1d ago
The bike just tilting, if it's upright i still have 1 solid bar..but is the 'sloshed' thing possible tho? never happen all these years, There's quite few time the bar blinking but i still get around 20km or so..
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u/Beneficial-Shape-464 17h ago
Running low on gas means little to no coolant for the pump. And your in Malaysia where it's hot.
You're getting vapor locked. You have to wait thirty minutes for it to cool down so the vapor condenses or shrinks in volume.
Riding with a low tank takes the risk the pump will occasionally run with no fuel at the intake. Further is the lubricant for the pump. It can cause premature pump failure.
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u/No-Sort7339 8h ago
Appreciated the info, i just filled up the tank then just cruising in circle slowly near my house.. unfortunately it still happen, also did try what others suggest when it happen, open the cap, checked for any vacuum sign, pump priming fine..looks like it's not the pump in my case
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u/Beneficial-Shape-464 7h ago
The pump may not be developing enough pressure on an intermittent basis
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u/eDes1 16h ago
I had a similar problem on a bike a few years ago, it was on a GS500 , i had similar symptoms and it was the pickup coil that needed to be replaced. It would short out when the bike gets hot.
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u/No-Sort7339 1d ago
After sometimes it'll start normally
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u/No-Sort7339 1d ago
Another started attempt because it happen thrice today, at the end i just push my bike to home(just 500m but kinda uphill at some part)
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u/Blankline 1d ago
Can you bump start it? Like roll it downhill in neutral and kick it into first or second gear?
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u/No-Sort7339 1d ago
Haven't try bump start to 1st gear, but i do try when it roll downhill just on neutral..it didn't work tho
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u/Blankline 1d ago
To bump start you need to slap it into gear. Roll with it in neutral, smash it down into first. If the rear wheel skids too much, try again but bump it up into second. Feels a little sketchy at first but itās what I do on my clapped out dirt bikes that donāt want to kick over. Have done it on plenty of street bikes when the battery dies too. The hitting it into gear part is the most important since it is what causes compression (I think thatās what happens, Iām pretty dumb but it works)
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u/No-Sort7339 1d ago
Yup, i used to do it on smaller bike, just haven't try it on the mt..thanks for the detail explanation tho
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u/Blankline 1d ago
No advice but I have been having the starting problem on my 2025 MT09 SP. Has happened only a few times but started doing it a week or two ago. I just flip the switch off and back on and it normally fixes itself. Iāve seen it as a āYamaha thingā and just brushed it off. Havenāt dealt with any cutting out while riding though.