Bizarre Ninja 250 Carb/Petcock Issue. Please Help!

jvernon · 11-11-2005

Hello,
So for about the past 2 months my Ninja 250 has been dumping gasoline out of the overflow in between the two carbs. After trying just about everything to fix the carbs and the float bowls, I decided to buy a new pair of carbs.
Guess what... same problem. When the engine is running, the carbs dump gasoline.
I then discovered that with the fuel switch off, the carbs stop dumping gas, but then start again when the fuel selector is turned to on. This led me to believe that maybe the petcock was damaged and forcing gas into the carbs, so I opened it up and cleaned it real well, but no change in the problem. And I also tried allowing air to escape from the tank to make sure there wasn't a pressure buildup, but that didn't help either.
What could possibly be going on!? I've totally run out of ideas.
Thanks,
Jess

chiatello · 11-11-2005

check the tubes and see if they are in good condition

i had a very similar problem, with consequences that looked very similar

and it turned out to be that a tube had rotted and had holes in it

jvernon · 11-11-2005

Which tube? I'll check them all, but which one failed for you? The main fuel line, the vacuum line from the carb to petcock, or something else?
I feel like though that if the vacuum line was leaking, the petcock wouldn't dispense fuel, and if the fuel line was leaking, the gas would come out there and not out of the overflow between the carbs.
I really think this is a pressure buildup issue, but I don't know how pressure could be building up and forcing gas into the carbs.
I'll check the lines and let you know what I find, but any other suggestions?

78_KZ750_Cafe · 11-11-2005

check/replace them all. if there is a problem in one line, there is a problem in all the lines. rubber installed on the same day will rot at the same rate.

jvernon · 11-11-2005

I checked the vacuum lines... no leaks. Any other thoughts?

78_KZ750_Cafe · 11-12-2005

underwear gnomes, perhaps helper monkeys. set up a surviellance camera.

not vacuum lines, fuel lines.

larrycavan · 11-12-2005

You don't think it's possible that you've just plain got crud in your fuel tank that's getting into your carbs do you ?

QKENUF4U · 11-12-2005

hey
just got back from a prev. customers house that ownes a 1985 GPZ900 w/ the same problem you do.
tore the carbs down and lots of crud to be found but that wasnt HIS problem. his floats are made of plastic and they are old so now they have filled with fuel which in turn causes the bowl to keep filling and filling and filling and filling and filling w/ fuel so it has to go somewhere.
i would pull the carbs and make sure the needle is actually sealing in the seat (look for a small groove on the needle tip) and make sure the floats are empty and that there is no dirt down in the seat area holding the needle open.
good luck

EX-Man · 11-13-2005

I had same problem with my EX500, I eventually got a petcock repair kit and rebuilt it, that seems to have solved the problem, maybe it's just worn out and needs replacing, if you're confident of your carbs.

jvernon · 11-13-2005

Okay, well I'm pretty confident that the carb needles aren't worn seeing as how they're new. But crud in the tank is an interesting idea, I'll look in to it.

Also, the dude with the EX500 - I have petcock issues too... every now and then it leaks. It's seems to happen mainly when I switch from off to on or reserve. What exactly was damaged in your petcock that caused it to flood the float bowls?

swimstarguy · 07-08-2008

necro-BUUUUUUUUUUMP.

I'm having the same problem as the OP.
The overflow between the two carbs is dumping gas when I ride. It's not leaking any gas when it's off. The lines are all fine, no holes to be found. When the fuel lines are disconnected to the petcock and it is turned to on, no fuel dumps out. I do not believe there's a problem with the vacuum diaphragm. It's not leaking anything near the petcock as well.

When I ride, gas just starts dumping. And it will surge constantly. There's zero power, it will just not take off (don't say that the problem's that it's only a 250...) The air box also has lots of gas pooling in it after I ride as well.

I do not know what the problem is. It just started doing that. No idea why. >_<

Any help would be appreciated.

Thanks!!!!

~Zar4

Ole Yeller · 07-08-2008

I say this without any meanness or rancor, but, some of the vacuum operated petcocks that Kaw uses are not the pinnacle of kaw engineering, IMHO.
I switched mine out for an old school ON/OFF/RES one because, now if I have this kind of issue, I at least know that it is my carb.

StarGate · 07-08-2008

I'm not sure what overflow you're talking about since you didn't post what bike you have. First guess would be a stuck float. Could also be trash in the float valve or a worn out valve.

swimstarguy · 07-09-2008

Sorry, my bad.
It's a 95 Ninja 250.

Suppose it is a stuck float or crap stuck in the float holding it open, how would we clean it out? Just take the carbs out at go to town on them with some carb cleaner? As far as I know, you're not supposed to do that because it's bad for all the little rubber seals in there.

~Zar4

07Ninja250 · 07-09-2008

If something's stuck in a float valve orifice, you're gonna have to remove the carbs, take the float bowls off, remove the floats and needles, and take a q-tip to the orifices. Might as well put in new needles while you've got it apart. Make sure the floats are actually floating. If they're deteriorated, they may not float on top of the gas as they should. Put everything back together, put the carbs back on the bike and start it up. (It'll take some cranking to get the bowls re-filled, so don't worry that it doesn't start at first).

After running for a minute or two, shut down and get about a 6" length of clear tubing that fits the 'nipples' on the bottom of the float bowls. Fit it on one of the 2 nipples and open the valve with an allen wrench, while holding the tubing facing upward next to the carb. When the tubing fills with gas, it'll tell you how high the fuel level is in the bowl. It shouldn't be any higher than the mating surface between the bowl and carb body. If it's higher, your floats need to be adjusted to keep LESS fuel in the bowls.

Sorry to get so detailed....I went through this with my '94.

swimstarguy · 07-09-2008

Thanks, get as detailed as possible.
I've messed with carbs before on another bike, I've just never encountered a problem like this. It just doesn't seem to make any sense as it happened out of nowhere. If it was tuned doubleplusrich, it would have been flooding out since it was last adjusted. Just one day it started surging and puking gas.

07ninja250, mind if I PM you should I need any more specific help? I'll be sure to post the solution with pics afterwards.

~Zar4

11-11-2005	#1 (permalink)
jvernon Newbie Join Date: Nov 2005 Posts: 4	Bizarre Ninja 250 Carb/Petcock Issue. Please Help! Hello, So for about the past 2 months my Ninja 250 has been dumping gasoline out of the overflow in between the two carbs. After trying just about everything to fix the carbs and the float bowls, I decided to buy a new pair of carbs. Guess what... same problem. When the engine is running, the carbs dump gasoline. I then discovered that with the fuel switch off, the carbs stop dumping gas, but then start again when the fuel selector is turned to on. This led me to believe that maybe the petcock was damaged and forcing gas into the carbs, so I opened it up and cleaned it real well, but no change in the problem. And I also tried allowing air to escape from the tank to make sure there wasn't a pressure buildup, but that didn't help either. What could possibly be going on!? I've totally run out of ideas. Thanks, Jess

11-11-2005	#2 (permalink)
chiatello Still On The Kickstand Join Date: Aug 2005 Location: Knoxville,TN,USA Posts: 28	check the tubes and see if they are in good condition i had a very similar problem, with consequences that looked very similar and it turned out to be that a tube had rotted and had holes in it __________________ 2000 Kawasaki Ninja 500r

11-13-2005	#9 (permalink)
EX-Man Foil Inspector BTK Beginner Join Date: Feb 2005 Location: SW FL. Posts: 104	I had same problem with my EX500, I eventually got a petcock repair kit and rebuilt it, that seems to have solved the problem, maybe it's just worn out and needs replacing, if you're confident of your carbs. __________________ NightRider

07-08-2008	#12 (permalink)
Ole Yeller Forum Supporter Forum Supporter Join Date: May 2008 Location: Space, the final frontier Posts: 295	I say this without any meanness or rancor, but, some of the vacuum operated petcocks that Kaw uses are not the pinnacle of kaw engineering, IMHO. I switched mine out for an old school ON/OFF/RES one because, now if I have this kind of issue, I at least know that it is my carb. __________________ 4 cylinders are better than 2 1985 ZL900 ELIMINATOR

07-08-2008	#13 (permalink)
StarGate Navy Vet Search & Rescue BTK Expert Join Date: Apr 2007 Location: NE Arkansas Posts: 6,117	I'm not sure what overflow you're talking about since you didn't post what bike you have. First guess would be a stuck float. Could also be trash in the float valve or a worn out valve. __________________ Mike Original Owner 1981 KZ1000-K1 LTD 2000 Suzuki King Quad Refurbish Photos

11-11-2005	#3 (permalink)
jvernon Newbie Join Date: Nov 2005 Posts: 4	Which tube? I'll check them all, but which one failed for you? The main fuel line, the vacuum line from the carb to petcock, or something else? I feel like though that if the vacuum line was leaking, the petcock wouldn't dispense fuel, and if the fuel line was leaking, the gas would come out there and not out of the overflow between the carbs. I really think this is a pressure buildup issue, but I don't know how pressure could be building up and forcing gas into the carbs. I'll check the lines and let you know what I find, but any other suggestions?

11-11-2005	#4 (permalink)
78_KZ750_Cafe Burt Munro Is My Hero BTK Expert Join Date: Jul 2005 Location: Clawson, MI Posts: 652	check/replace them all. if there is a problem in one line, there is a problem in all the lines. rubber installed on the same day will rot at the same rate.

11-11-2005	#5 (permalink)
jvernon Newbie Join Date: Nov 2005 Posts: 4	I checked the vacuum lines... no leaks. Any other thoughts?

11-12-2005	#6 (permalink)
78_KZ750_Cafe Burt Munro Is My Hero BTK Expert Join Date: Jul 2005 Location: Clawson, MI Posts: 652	underwear gnomes, perhaps helper monkeys. set up a surviellance camera. not vacuum lines, fuel lines.

11-12-2005	#7 (permalink)
larrycavan Foil Inspector BTK Beginner Join Date: Oct 2005 Posts: 114	You don't think it's possible that you've just plain got crud in your fuel tank that's getting into your carbs do you ?

11-12-2005	#8 (permalink)
QKENUF4U AZ's Official Mechanic BTK Expert Join Date: Sep 2004 Location: lake havasu city arizona Posts: 4,551	hey just got back from a prev. customers house that ownes a 1985 GPZ900 w/ the same problem you do. tore the carbs down and lots of crud to be found but that wasnt HIS problem. his floats are made of plastic and they are old so now they have filled with fuel which in turn causes the bowl to keep filling and filling and filling and filling and filling w/ fuel so it has to go somewhere. i would pull the carbs and make sure the needle is actually sealing in the seat (look for a small groove on the needle tip) and make sure the floats are empty and that there is no dirt down in the seat area holding the needle open. good luck

11-13-2005	#10 (permalink)
jvernon Newbie Join Date: Nov 2005 Posts: 4	Okay, well I'm pretty confident that the carb needles aren't worn seeing as how they're new. But crud in the tank is an interesting idea, I'll look in to it. Also, the dude with the EX500 - I have petcock issues too... every now and then it leaks. It's seems to happen mainly when I switch from off to on or reserve. What exactly was damaged in your petcock that caused it to flood the float bowls?

07-08-2008	#11 (permalink)
swimstarguy Newbie Join Date: Jul 2008 Posts: 3	necro-BUUUUUUUUUUMP. I'm having the same problem as the OP. The overflow between the two carbs is dumping gas when I ride. It's not leaking any gas when it's off. The lines are all fine, no holes to be found. When the fuel lines are disconnected to the petcock and it is turned to on, no fuel dumps out. I do not believe there's a problem with the vacuum diaphragm. It's not leaking anything near the petcock as well. When I ride, gas just starts dumping. And it will surge constantly. There's zero power, it will just not take off (don't say that the problem's that it's only a 250...) The air box also has lots of gas pooling in it after I ride as well. I do not know what the problem is. It just started doing that. No idea why. >_< Any help would be appreciated. Thanks!!!! ~Zar4

07-09-2008	#14 (permalink)
swimstarguy Newbie Join Date: Jul 2008 Posts: 3	Sorry, my bad. It's a 95 Ninja 250. Suppose it is a stuck float or crap stuck in the float holding it open, how would we clean it out? Just take the carbs out at go to town on them with some carb cleaner? As far as I know, you're not supposed to do that because it's bad for all the little rubber seals in there. ~Zar4

07-09-2008	#15 (permalink)
07Ninja250 Way Too Much Free Time BTK Expert Join Date: May 2008 Location: Plano, TX Posts: 1,186	If something's stuck in a float valve orifice, you're gonna have to remove the carbs, take the float bowls off, remove the floats and needles, and take a q-tip to the orifices. Might as well put in new needles while you've got it apart. Make sure the floats are actually floating. If they're deteriorated, they may not float on top of the gas as they should. Put everything back together, put the carbs back on the bike and start it up. (It'll take some cranking to get the bowls re-filled, so don't worry that it doesn't start at first). After running for a minute or two, shut down and get about a 6" length of clear tubing that fits the 'nipples' on the bottom of the float bowls. Fit it on one of the 2 nipples and open the valve with an allen wrench, while holding the tubing facing upward next to the carb. When the tubing fills with gas, it'll tell you how high the fuel level is in the bowl. It shouldn't be any higher than the mating surface between the bowl and carb body. If it's higher, your floats need to be adjusted to keep LESS fuel in the bowls. Sorry to get so detailed....I went through this with my '94.

07-09-2008	#16 (permalink)
swimstarguy Newbie Join Date: Jul 2008 Posts: 3	Thanks, get as detailed as possible. I've messed with carbs before on another bike, I've just never encountered a problem like this. It just doesn't seem to make any sense as it happened out of nowhere. If it was tuned doubleplusrich, it would have been flooding out since it was last adjusted. Just one day it started surging and puking gas. 07ninja250, mind if I PM you should I need any more specific help? I'll be sure to post the solution with pics afterwards. ~Zar4

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