Another Starting Issue Thread

GenuineChevy39

GenuineChevy39

Registered
The bike:
03 with under 26,000km
small airbox mod
stock filter (clean)
D & D slip ons
Marble mod

In the last few days i have noticed the bike is taking longer to start up. Usually it takes a touch of the starter button and she fires. Now it takes about 3-4 seconds whether the bike is hot or cold. The bike runs the same as the day i got it. No hesitation, no bogs, no backfires.

The battery is about 3 months old. With the bike off it sits at 12.4-12.9. at idle its around 14.5 and with some throttle it's about 14.9. That was as deep into the electrical end as i went.

I was going to check the spark plugs as i don't know if they were ever replaced so i pulled the air box off and that's when i realized i didn't have any extensions with me for my ratchet set (i keep my tools at my parents shop). So for the hell of it i decided to fire the bike up without the airbox. A split second after i hit the button it fired right up and ran great. Tried a bunch of times and it continued to fire up no problem.

I put the bike back together and went to fire it up again and its back to the same issue. So i'm either thinking it's one of the sensors on the air box or maybe a clogged fuel line or filter? Maybe with the tank up it helps push the fuel through the lines?? I'm kinda stumped so any help would be greatly appreciated.
 
Sounds like a failing fuel pump, lifting the fuel tank, will give a better 'head' of fuel weight, it could also be a partially blocked fuel filter (it's located in a moulded plastic holder, next to the fuel pump, in the tank).
Can you fill the tank right up and note if it gets harder to start, as the fuel level drops? That's an easy test.
 
David Offor said:
Sounds like a failing fuel pump, lifting the fuel tank, will give a better 'head' of fuel weight, it could also be a partially blocked fuel filter (it's located in a moulded plastic holder, next to the fuel pump, in the tank).
Can you fill the tank right up and note if it gets harder to start, as the fuel level drops? That's an easy test.
Click to expand...

It has a half tank right now so i will fill it up tonight and see how that goes. Thank you
 
So filling up the tank didn't make any difference. Now it seems intermittent. This weekend i will strip all the fairings off to check wire connectors and grounds. I know my 99 SRAD's had serious issues with the connectors in the plugs arcing causing the wires to burn. Not sure if this is the same on the Busa but that was usually my "go to" on the SRAD.
 
Is this a lead acid battery? (I am unfamiliar with specs of other types.) It is unclear from your post but if the battery is charged, then left to rest for 24 hours, and the resting voltage is 12.4V, that is 65% depleted which is significant for a newer battery and would point to an electrical problem. Was there a reason for the battery swap or did the prior battery last until a good natural age? Do all of the electrical checks in the manual, such as voltage at 5,000 RPM, stator AC voltages, and stator impedances, check for shorts with the bike off. From your stats I wonder if the peak voltage will exceed the spec. That would point to a rectifier and a battery that is damaged and cannot provide the current needed.
 
Hayabusa Wannabe said:
Is this a lead acid battery? (I am unfamiliar with specs of other types.) It is unclear from your post but if the battery is charged, then left to rest for 24 hours, and the resting voltage is 12.4V, that is 65% depleted which is significant for a newer battery and would point to an electrical problem. Was there a reason for the battery swap or did the prior battery last until a good natural age? Do all of the electrical checks in the manual, such as voltage at 5,000 RPM, stator AC voltages, and stator impedances, check for shorts with the bike off. From your stats I wonder if the peak voltage will exceed the spec. That would point to a rectifier and a battery that is damaged and cannot provide the current needed.
Click to expand...

The battery i put in is a Yuasa YT12A-BS. The reason i replaced the battery is because when i bought the bike it wouldn't crank at all. I know the bike has done a lot of sitting in its lifetime as it only had 24,000 km on it. This weekend i will get more into it.

Mathewrussell52 said:
I would look fuel first sounds like clogged filter. It runs sucks up all debree makes it hard to start then sits sediment sinks and fires right up.

And this is prob one of most common issues on these old busas.

Chrisjp did a great fix thread also

https://www.hayabusa.org/forum/threads/fuel-filter-mod.175027/
Click to expand...

This is more what i am leaning towards. With the bike being more of a garage ornament in its early life i'm sure it sat around with bad fuel in it causing the filters to clog.
 
ok so i am going to go out on a limb here. Is the wether starting to get a little cooler there? My older bus used to do that, as the weather would change i noticed the bus would start different.
 
VIPER said:
ok so i am going to go out on a limb here. Is the wether starting to get a little cooler there? My older bus used to do that, as the weather would change i noticed the bus would start different.
Click to expand...

In the morning and evening it gets a bit cooler but i first noticed it when it was 25*c and sunny out.
 
Little update,

Did an oil change over the weekend. Checked some of the wires for signs of a bad connection and couldn't find anything. Tested the electrical after i plugged it back together and it seemed fine. I don't remember exact numbers but the bike was 14.5v at idle, 14.2v at 3000rpm and 14.09v at 5000rpm which seem normal to me. I don"t have a book for the busa yet but the numbers seem right.

Anyway, i have had no starting issues since although i have only been on the bike a few times as the weather here has been really shitty. That being said it was pretty chilly last night and she fired right up.

jermzfree said:
What rpm idling? Might just need a throttle cable adjustment.
Click to expand...

Bike idles at 1100-1200 rpm
 
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