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Random bucking/hesitation/stalling.

91K views 269 replies 74 participants last post by  kamping 
#1 ·
Well, the honeymoon is over.

After buying mt 2005 ZX6R and riding it for about 400 miles, I am noticing a couple of issues. The most important being a strange hesitation and stalling issue. What happens is, I ride it and it runs fine for about 20 miles. Then somewhere between 20 and 30 miles, the bike will randomly start bucking and stall out at highway speeds. Attempts to restart it fail so when this happens, I pull over, wait 10 minutes and the bike starts and is good for another 20 miles or so. The only thing I find strange is that when cruising at 70mph on a 90* day, my temps sit around 215 to 220. Yes, the fan is on constantly. I have swapped the battery, checked coolant, checked fuses, changed the oil, etc.. Nothing seems to help.

Also, I used to own suzukis and I never heard the gas cap whistle.. This thing does. I assume it is to release fumes but it kinda sketched me out the first time I heard it. I assume this is normal unless someone tells me otherwise.

Any ideas about the stalling issue?
 
#3 ·
It sounds like a gas tank vent line kink. Gas cap should not wistle.. what's happening is as the bike requires more fuel at higher engine revs air needs to enter the fuel tank so fuel can leave the tank.. what you have now is a sort of vacuum inside the fuel tank causing the engine to starve for fuel.

Lift the tank up and check the vent lines, i would even remove the vent lines and blow them out with compressed air or run a piece of soft wire thru the hose to clear out any potential blockage. Reinstall the lines and run them so when the tank is on the bike they aren't kinked anywhere.

If that does not solve the problem, come back.
 
#4 ·
It sounds like a gas tank vent line kink. Gas cap should not wistle.. what's happening is as the bike requires more fuel at higher engine revs air needs to enter the fuel tank so fuel can leave the tank.. what you have now is a sort of vacuum inside the fuel tank causing the engine to starve for fuel.

Lift the tank up and check the vent lines, i would even remove the vent lines and blow them out with compressed air or run a piece of soft wire thru the hose to clear out any potential blockage. Reinstall the lines and run them so when the tank is on the bike they aren't kinked anywhere.

If that does not solve the problem, come back.
some kawi tanks do vent, and whistle..its pretty common.

but agreed, check the above(cant hurt)...might also be the reasons for it running poorly.
 
#5 ·
I checked the lines for kinks but didn't see anything. I will try yo blow them out though.

I just find it odd that it happends between the 20-30 mile mark. I had thought that it was heat related. Like the stator getting overheated and not outputting enough juice at high RPMs..

I had similar problems in my 90 AWD Talon race car a long time ago and it turned out to be the evap can. That is why I thought the whistling gas cap may have something to do with it. The only thing that changed from it acting normal to this stalling problem was I did an oil change. I don't see anything pinched but I will check.

Another quick question.. There are 3 hoses that hang out in the left fairing. One is (I assume) coolant overflow. There are also 2 vacuum hoses that just hang there as well. Are they the gas tank vent tubes? I can get a pic if anyone is interested.
 
#6 ·
fuel filter or something clogging the fuel pickup point would be my guess.
 
#7 ·
Ok, well last night I checked the vent lines and they are fine. But here is an interesting piee of info..

I took it out and rode it until it started bucking and stalled. Typically I have to sit there for 10-15 mins until it will start again. So thinking it is something with the gas tank, I opened it up after I stopped the bike. When opening the gas filler cap, there was a "whoosh" of air (sounded like when you open a 2 liter of coke". I immediately closed it and the bike fired right up.

There has got to be something going on with the fuel system but I am not sure where to go from here. Does this new info help any?
 
#8 ·
#9 ·
Pvt. Donkey,

Did you get this fixed or take it somewhere? Inquiring minds want to know!

Ethan
 
#10 ·
Welcome to the crappy world of the 05 636..... Ive been having this issue for a month now.. Ive read all over the Web people having the same issue with no reason y.. on thing I did do was changed the plugs... mine were pitch black... one I did that it runs pretty good but still every once in a blue moon it still bucks....
 
#13 · (Edited)
ZX6RRNewbie - Thanks for the help... :Damn: :lame:


Anyway.. I have since rerouted all of the tank breather lines, changed the coolant and done extensive road testing. Yesterday the ambient temp was about 85 degrees and low humidity. I didn't have any issues.

So today I am on the bike for about 45 mins and it happens again.. sputters, bucks and stalls. It HAS to be temp related at this point. I am wondering if maybe the fuel pump is getting overheated. My temps yesterday were 185 cruising and 215 sitting at a light. Today it was 98 degrees, I was seeing ~230 when stopped and 215 while cruising. I am running water wetter, and 30/70 coolant/water mix and it is still ridiculously hot. Failing water pump maybe?

EDIT: I forgot to mention that I did verify that the lines were clear. I completely removed them and cleaned them using a soft rifle cleaning rod. No obstructions. As a matter of fact, after doing so and rerouting the lines, the gas cap whistle stopped.
 
#16 ·
I was thinking maybe a head gasket but the fluid is clean and I'm not seeing any white smoke. I have also pulled the plugs and I don't see any signes of pre-ignition. Besides, I ran CAM2 a few weeks ago and still had the stalling problem. So I doubt it is that. This shit is annoying. It just isn't consistant enough to diagnose.
 
#17 ·
this really does sound like some sort of vapor lock, but I'm at a loss right now.
 
#18 ·
Hummm this is interesting. My 2005 6R is showing signs of a similar problems. It started doing it at the end of my racing at RA and now ever since and I can't figure it out. The bike "bucks" it doesn't stall just "bucks" and only when I am leaned over in a turn at steady high RPM's(which is really dangerous). Maybe 2 or 3 times and then I am picking the bike up and back on the throttle. I can't pin it to only left or right turns but seems to happen more on left turns then right turns. I am also running wetter water and actually blew the hose off of my water pump yesterday at the track while testing it. I kept thinking it was an ignition issue but I never throw a check engine. Also I am running the KIT ECU so if my problem is the same then it can't be the ECU for us.
 
#19 ·
Yikes.. Yeah, it is pretty scary when it happens. Not because of loss of control or anything but.. well.. for instance: I was on 495 today (which is an insane highway as it is here in DC) and traffic is merging. So I downshift and take off. all is well at first but suddenly as I am moving to the right lane, it starts bucking and stalls...... at 98 MPH with traffic doing a good 85-90. I had to nurse it across 3 lanes to the shoulder.. ugh. The shit nightmares are made of.

But yeah, the only constant is the temperature of the bike. When it is cool, no issues, when it is hot, is when the stalling seems to happen.. But not always. It is killing me. I fucking love this bike but the stalling is making me reconsider my choice. I have never had a problem like this with my GSXRs so it is a little disappointing that I have a bike that can demolish a GSXR600 but won't stay running.

So any suggestions to lower the temp? Higher RPM fan? Better coolant? Let's hear some ideas. I still have a strong feeling that the heat is making the fule pump shit the bed.
 
#20 ·
I don't think the temps are to blame well not entirely. I ride in Central Texas which now a days is REALLY HOT!! 105 oF ambient when I'm riding home from work. I run about the same temps as you do and never have any problems. 215 stopped at a light is very common I've seen as high as 225 oF. I think you should try to get a new ECU or a borrowed ECU and change it out to see if that works. I've heard about ECU's getting hot and causing a malfunction similar to yours.

I use the original coolant, I've thought of using water wetter but haven't yet. You said you checked the coolant but are you sure the radiator is full?

You said that you've ridden this bike for about 400 miles, are these the only miles on the bike or is this a used bike and could it have been abused by a previous owner?
 
#23 ·
See, I tend to think that the heat is to blame because when the ambient temp is 95 and low humidity my temps should not get up to 238 when idling. I can feel the hot air blasting out from the fan and the temps drop some but they still hover around 230..

So even if the problem isn't related to my temps, I still need to figure out a way to lower them. Once I have eliminated the temps being a contributor, I can go from there.
 
#26 ·
okay here's my input to this since this happened to me just the other week too.

here's my scenario and what i found;
riding home (42 mile trek with 10 of it being on suface streets and the rest on the hwy) outside temp around 110 and bike temp in the mid 220's once i hit the surface streets. it wasn't till i was about 2 miles away from the house when it died the first time going across an intersection. i had enough mometum to pull it over into a bus stop. sat for about 5 minutes and it started again. went down the road about 3/4 mile where it died for the second time on me. again sat for 5 minutes and started right up. died for the last time that day about another 3/4 mile further along, now at least i was only 100 yards from the house. once home, let the bike sit for a few days while i try to find out what my problem might be.

this has never happened to me until this day and have been following this post from the start since it happen to be the same day that i had my issue.

this is what i found; my vent line was infact pinched/kinked from the last time i had my tank up and the excessive heat of the bike and the weather made it too much for it to vent correctly. i had previously put in a full tank like this without any problems of the bike cutting off. i test this by using a small kitchen funnel and a little bit of water to see if it would drain from the side of the fuel cap area and it didn't. i started tugging on the vent line and sure enough it was kinked. as soon is i pulled it straight, the water drained right out.

i know you tested your lines to see if it was clogged but did you test it while on the bike and the tank down and secure? if this doesn't fix your problem then i'm not sure what yours might be. i just wanted to give you a solution to what another rider that had a similar problem found.
 
#27 ·
okay here's my input to this since this happened to me just the other week too.

here's my scenario and what i found;
riding home (42 mile trek with 10 of it being on suface streets and the rest on the hwy) outside temp around 110 and bike temp in the mid 220's once i hit the surface streets. it wasn't till i was about 2 miles away from the house when it died the first time going across an intersection. i had enough mometum to pull it over into a bus stop. sat for about 5 minutes and it started again. went down the road about 3/4 mile where it died for the second time on me. again sat for 5 minutes and started right up. died for the last time that day about another 3/4 mile further along, now at least i was only 100 yards from the house. once home, let the bike sit for a few days while i try to find out what my problem might be.

this has never happened to me until this day and have been following this post from the start since it happen to be the same day that i had my issue.

this is what i found; my vent line was infact pinched/kinked from the last time i had my tank up and the excessive heat of the bike and the weather made it too much for it to vent correctly. i had previously put in a full tank like this without any problems of the bike cutting off. i test this by using a small kitchen funnel and a little bit of water to see if it would drain from the side of the fuel cap area and it didn't. i started tugging on the vent line and sure enough it was kinked. as soon is i pulled it straight, the water drained right out.

i know you tested your lines to see if it was clogged but did you test it while on the bike and the tank down and secure? if this doesn't fix your problem then i'm not sure what yours might be. i just wanted to give you a solution to what another rider that had a similar problem found.
I will surely take another look. Just to be clear, can you explain how you tested the line with the tank down and the line secure? Also, how many total vents does the tank have? I know the gas filler cap itself has a vent, there is one coming from the front of the tank (close to the air box). Is there another one that I am missing?
 
#28 · (Edited)
Here is a shitty MSPaint version of what I know. The 2 vents I am aware of are circled in red.

But..... If I look at the left (driver's side) of the bike I have 3 hoses. One is clearly a gas tank vent as I can smell fuel when I sniff it. The other is the coolant overflow and the 3rd, I don't know really. It doesn't smell like anything. It was tucked under the tank but I freed it up last time I had the fairing off so it is clear of any pinch points. This 3rd hose doesn't smell like anything and does not leak anything so I am unsure what it is for. I never did trace it as it looked like it did not go to the gas tank.

 
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