yfz450r running very poorly! please help!!! - Yamaha YFZ450 Forum : YFZ450, YFZ450R, YFZ450X Forums

yfz450rjunky · 10-19-2011, 02:21 PM

i own a 2009 stock yfz450r and have had it now for 9 months. all of a sudden at the track the yfz450r doesn't want to run anymore past half-throttle, it just cuts out like it ran out of gas and starting backfiring but when i ease up on the throttle a little bit then it runs again. to me it sounds like a fuel problem but i have had the fuel pump pressure tested and it has exactly what the manual calls for. my check engine light is not on and it starts off really nicely! just doesn't want to run past half-throttle to 3/4 throttle like the ecu doens't let it go past. it just happend out of the blue! when the quad hits rev-limiter in nuetral i have 6" flames shooting out of my pipe! is there anybody at all that can help me in anyway????!!!!!!! i'm completely out of ideas and at the end of my rope!

YFZ450Rider43 · 10-19-2011, 02:22 PM

Quote:

Originally Posted by yfz450rjunky

i own a 2009 stock yfz450r and have had it now for 9 months. all of a sudden at the track the yfz450r doesn't want to run anymore past half-throttle, it just cuts out like it ran out of gas and starting backfiring but when i ease up on the throttle a little bit then it runs again. to me it sounds like a fuel problem but i have had the fuel pump pressure tested and it has exactly what the manual calls for. my check engine light is not on and it starts off really nicely! just doesn't want to run past half-throttle to 3/4 throttle like the ecu doens't let it go past. it just happend out of the blue! when the quad hits rev-limiter in nuetral i have 6" flames shooting out of my pipe! is there anybody at all that can help me in anyway????!!!!!!! i'm completely out of ideas and at the end of my rope!

Any mods? Gotta give us an idea of what you have done. Was it your first time at a track with a large elevation change?

yfz450rjunky · 10-19-2011, 02:30 PM

i haven't done any mods and is still completely stock. has been running really good for 9 months but now all of a sudden its running bad. no it hasn't been my first time. i've been on the track with large elevation changes for 6 months now. changed the oil and oil filter 2 times a month and cleaned the air filter once a week. i am running 10w50 semi-synthetic yamalube oil.

jayracingman · 10-19-2011, 10:30 PM

Check your spark plug, throttle position sensor, coil and the way these quads are the wiring harness for grounds.

pogipogi · 10-19-2011, 11:08 PM

I haven't had any problems with mine... I would say check the spark plug. Also is your warranty up? I think they are 6 months on that quad. make sure the injector or something isn't loose either..

yfz450rjunky · 10-20-2011, 12:53 AM

i thought it was the spark plug too so i replaced it with an iridium spark plug but it didn't change anything. i also checked the throttle position sensor and coil and all are like they are suppose to be. since i live in Belize, Central America; sadly the nearest dyno or Yamaha shop is in the U.S. so i would have to ship it there and back which would cost me around 2000 bucks :-( I'm really surprised nobody has had this happen to their quad before! thanks guys for posting so far :-)

yfz450rjunky · 10-21-2011, 10:34 AM

bump

cpenalty217 · 10-21-2011, 12:03 PM

Almost sounds like it is sucking air from somewhere other than the air filter. Check all the connections from the filter to the motor maybe a boot slipped off.

yfz450rjunky · 10-21-2011, 08:30 PM

yah thats what it sounds like to me too but i have taken it apart once already and everything looked fine. i'll take it apart as soon as i have time and double check everything to be sure. oh and i should mention that the problem is on and off. the problem will get worst then the next day it runs totally fine only to run twice as bad the day after. thats what got me puzzled! do you think my wire harness is rubbing against somewhere and its shorting or somewhere the wire harness just doesn't have good connection?

L4UR3NS_95 · 10-22-2011, 08:00 AM

Could be, check you're wires and maybe it isn't a bad idea to clean your adaptors.

Ripcityrider2010 · 10-22-2011, 08:59 AM

The yfzr's have problems with the wiring harness rubbing next to left front shock tower and back by the air box where drops over the frame into the rear of the bike. Check these two areas for bad connections.

yfz450rjunky · 10-22-2011, 10:31 AM

thanks alot for that info!! I'll get right on that and check all my wiring harness contacts! is there a grease that's specifically designed for electric plugs so it gets better contact?

L4UR3NS_95 · 10-22-2011, 10:51 AM

I always use WD40 and it works perfect.

hillbilly123 · 10-28-2011, 08:31 AM

Check the screen on the fuel injector. Mine plugged up from debri in the aftermarket tank i had. Cleaned it out very gently, seems to run good now. If you run it too much plugged up you may have to change the injector. Hope this helps

yfz450rjunky · 10-29-2011, 12:22 AM

the first thing i did was to take the fuel pump out to check how dirty the filter would be but it was completely clean. so just in case i removed the throttle body and checked the fuel injector but it also appeared to be clean! finally just to be safe i mixed a bit of fuel injector cleaner with my gas...

daddio · 10-29-2011, 12:13 PM

My first YFZR did almost the exact same thing. Check the harness at the front of the tank as it snakes through the frame by the left front shock mount. I had 4 wires that were rubbed through and shorting. It also did not throw a check engine code. It just wouldn't run past 1/2 throttle, and would sometimes quit.

yfz450rjunky · 10-29-2011, 09:13 PM

thanks for the info daddio!! somewhat boosts what confidence i have left in this bike!!! should get plenty of time tomorrow to pull the bike apart!.....again!

yfz450rjunky · 10-30-2011, 01:40 AM

what do you guys use to grease the electric contacts? besides wd-40...

1shooter · 10-30-2011, 09:14 AM

Without sounding to rude, living in a different country. I could be bad gas.

Make sure it it is at least 92. If not add some octane booster.

Some gas stations here in the us, that are not so much on the up and up dump a lower grade gas in a higher grade gas well. So you think you are getting good gas but your not.

If thats the case you could rip stuff apart for the rest of you life and never figure it out.

daddio · 10-30-2011, 11:11 AM

Quote:

Originally Posted by yfz450rjunky

what do you guys use to grease the electric contacts? besides wd-40...

Dialectric grease, sold at auto parts and hardware stores.

10-19-2011, 02:21 PM	#1 (permalink)
yfz450rjunky Member Join Date: Sep 2010 Posts: 76	yfz450r running very poorly! please help!!! i own a 2009 stock yfz450r and have had it now for 9 months. all of a sudden at the track the yfz450r doesn't want to run anymore past half-throttle, it just cuts out like it ran out of gas and starting backfiring but when i ease up on the throttle a little bit then it runs again. to me it sounds like a fuel problem but i have had the fuel pump pressure tested and it has exactly what the manual calls for. my check engine light is not on and it starts off really nicely! just doesn't want to run past half-throttle to 3/4 throttle like the ecu doens't let it go past. it just happend out of the blue! when the quad hits rev-limiter in nuetral i have 6" flames shooting out of my pipe! is there anybody at all that can help me in anyway????!!!!!!! i'm completely out of ideas and at the end of my rope!

10-22-2011, 08:59 AM	#11 (permalink)
Ripcityrider2010 Senior Member Join Date: Dec 2010 Location: southeastern PA Posts: 530	The yfzr's have problems with the wiring harness rubbing next to left front shock tower and back by the air box where drops over the frame into the rear of the bike. Check these two areas for bad connections. __________________ 09 YFZ450R- Pro Armor Revolution Nerf Bars, Pro Armor Cross Country Bumper, Rath Grab bar, PRM Skidplate, Dasa Full Exhaust, MSD Blaster Ignition, Pro Flow Intake, Precision Stabilizer, Racetech suspension conversion, 07 intake cam, GYTR kill switch, ODI Lock-on grips, Custom Dyno tune by Stump's Garage, Houser + 2" stem, Speedlinez front brake lines, Steel braided throttle cable, Steel braided clutch cable

10-29-2011, 12:13 PM	#16 (permalink)
daddio Senior Member Join Date: Feb 2004 Posts: 3,246	My first YFZR did almost the exact same thing. Check the harness at the front of the tank as it snakes through the frame by the left front shock mount. I had 4 wires that were rubbed through and shorting. It also did not throw a check engine code. It just wouldn't run past 1/2 throttle, and would sometimes quit. __________________ Mechanic ITP & WORCS Pro #191 Daddio19@Gmail.com

10-19-2011, 02:30 PM	#3 (permalink)
yfz450rjunky Member Join Date: Sep 2010 Posts: 76	i haven't done any mods and is still completely stock. has been running really good for 9 months but now all of a sudden its running bad. no it hasn't been my first time. i've been on the track with large elevation changes for 6 months now. changed the oil and oil filter 2 times a month and cleaned the air filter once a week. i am running 10w50 semi-synthetic yamalube oil.

10-19-2011, 10:30 PM	#4 (permalink)
jayracingman Member Join Date: Jul 2009 Posts: 65	Check your spark plug, throttle position sensor, coil and the way these quads are the wiring harness for grounds.

10-19-2011, 11:08 PM	#5 (permalink)
pogipogi Junior Member Join Date: Oct 2011 Posts: 12	I haven't had any problems with mine... I would say check the spark plug. Also is your warranty up? I think they are 6 months on that quad. make sure the injector or something isn't loose either..

10-20-2011, 12:53 AM	#6 (permalink)
yfz450rjunky Member Join Date: Sep 2010 Posts: 76	i thought it was the spark plug too so i replaced it with an iridium spark plug but it didn't change anything. i also checked the throttle position sensor and coil and all are like they are suppose to be. since i live in Belize, Central America; sadly the nearest dyno or Yamaha shop is in the U.S. so i would have to ship it there and back which would cost me around 2000 bucks :-( I'm really surprised nobody has had this happen to their quad before! thanks guys for posting so far :-)

10-21-2011, 10:34 AM	#7 (permalink)
yfz450rjunky Member Join Date: Sep 2010 Posts: 76	bump

10-21-2011, 12:03 PM	#8 (permalink)
cpenalty217 Member Join Date: Sep 2011 Location: Sand Mountain, Utah Posts: 64	Almost sounds like it is sucking air from somewhere other than the air filter. Check all the connections from the filter to the motor maybe a boot slipped off.

10-21-2011, 08:30 PM	#9 (permalink)
yfz450rjunky Member Join Date: Sep 2010 Posts: 76	yah thats what it sounds like to me too but i have taken it apart once already and everything looked fine. i'll take it apart as soon as i have time and double check everything to be sure. oh and i should mention that the problem is on and off. the problem will get worst then the next day it runs totally fine only to run twice as bad the day after. thats what got me puzzled! do you think my wire harness is rubbing against somewhere and its shorting or somewhere the wire harness just doesn't have good connection?

10-22-2011, 08:00 AM	#10 (permalink)
L4UR3NS_95 Junior Member Join Date: Oct 2010 Location: Belgium Posts: 23	Could be, check you're wires and maybe it isn't a bad idea to clean your adaptors.

10-22-2011, 10:31 AM	#12 (permalink)
yfz450rjunky Member Join Date: Sep 2010 Posts: 76	thanks alot for that info!! I'll get right on that and check all my wiring harness contacts! is there a grease that's specifically designed for electric plugs so it gets better contact?

10-22-2011, 10:51 AM	#13 (permalink)
L4UR3NS_95 Junior Member Join Date: Oct 2010 Location: Belgium Posts: 23	I always use WD40 and it works perfect.

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10-28-2011, 08:31 AM	#14 (permalink)
hillbilly123 Junior Member Join Date: Oct 2011 Posts: 21	Check the screen on the fuel injector. Mine plugged up from debri in the aftermarket tank i had. Cleaned it out very gently, seems to run good now. If you run it too much plugged up you may have to change the injector. Hope this helps

10-29-2011, 12:22 AM	#15 (permalink)
yfz450rjunky Member Join Date: Sep 2010 Posts: 76	the first thing i did was to take the fuel pump out to check how dirty the filter would be but it was completely clean. so just in case i removed the throttle body and checked the fuel injector but it also appeared to be clean! finally just to be safe i mixed a bit of fuel injector cleaner with my gas...

10-29-2011, 09:13 PM	#17 (permalink)
yfz450rjunky Member Join Date: Sep 2010 Posts: 76	thanks for the info daddio!! somewhat boosts what confidence i have left in this bike!!! should get plenty of time tomorrow to pull the bike apart!.....again!

10-30-2011, 01:40 AM	#18 (permalink)
yfz450rjunky Member Join Date: Sep 2010 Posts: 76	what do you guys use to grease the electric contacts? besides wd-40...

10-30-2011, 09:14 AM	#19 (permalink)
1shooter Junior Member Join Date: Mar 2006 Posts: 25	Without sounding to rude, living in a different country. I could be bad gas. Make sure it it is at least 92. If not add some octane booster. Some gas stations here in the us, that are not so much on the up and up dump a lower grade gas in a higher grade gas well. So you think you are getting good gas but your not. If thats the case you could rip stuff apart for the rest of you life and never figure it out.