Bike is hard starting when hot

[Jbaker229]

For someone reason my RX has a ton of trouble starting after it has been warmed up. It seems like the injectors are not pumping fuel into the bike once it has been warmed up. I have been getting the occasional 02 sensor error - so I am wondering if replacing the 02 sensors will solve my problem? I was also wondering if a race ECM would help things out.

[mackja]

I am dealing with the same issue, actually it seems to be flooding out. I just sent an email to EBR tech, will share info as soon as I recieve it.

[zviadi]

http://ebrforum.com/showthread.php?377-Chain-slap-and-O2-code

[buell-fan]

Check to make sure your throttle body are seated and attached properly. They have been being "blown" up off their proper locations causing other owner's issues starting and running properly.

[Jbaker229]

Check to make sure your throttle body are seated and attached properly. They have been being "blown" up off their proper locations causing other owner's issues starting and running properly.


Thanks I will take a look - I have had the bike backfire really badly before - but only after I had issues with starting it (bike backfires on start if you give it gas).


I am dealing with the same issue, actually it seems to be flooding out. I just sent an email to EBR tech, will share info as soon as I recieve it.

Thanks! Let me know if you hear anything, I think my issue is their is too little gas when the bike is hot.

[mackja]

Got in touch with EBR and talked with the fuel evap engineer, possible cause is the purge valve is not working, check the line going down to the cylinder under the throttle bodies by turning ignitin off and place a vaccuum on the purge valve, should pull down to 0 if not needs to be replaced, second after running the bike with engine off look at live timming fuel pressure, pump will cycle after engine off fuel pressue should varie from 400-500kpa, if number fall off quickly fuel injector is leaking fuel into the cylinder or fuel pump is bad, and will cause a hard start problem. If it falls off slowly that is normal. Hope this helps.

[mackja]

Checked the fuel pressure with engine off key on, everything is normal, next I checked the purge valve and it was faulty, would not hold a vacuum, good thing is I just happened to have an extra one on hand. Started up immediately, real test will be at Jennings GP next month.

[Jbaker229]

Checked the fuel pressure with engine off key on, everything is normal, next I checked the purge valve and it was faulty, would not hold a vacuum, good thing is I just happened to have an extra one on hand. Started up immediately, real test will be at Jennings GP next month.


Thank you so much, my bike is sitting in North GA about 50 miles from my house - I will check tomorrow. You pick your bike up from Rider's Hill?

[mackja]

Thank you so much, my bike is sitting in North GA about 50 miles from my house - I will check tomorrow. You pick your bike up from Rider's Hill?

Bought both my rx and sx from David and Anthony at Rider's Hill, sure do miss that place, hate they closed up shop.

[noone1569]

Mine has the same issue; suppose I need to follow Mack's advise up there.

[mackja]

check one other thing also. Throttle bodies can come loose and cause an air leak, make sure they are mounted all the way down, best way to make sure is with a flashlight open the throttle and look down the throat and see if their is a gap between the aluminum and the plastic intakes, should be no gap at all, loosen up lower clamp push down until properly seated and tighten snugly, becarefull not to over tighten or you could split the rubber sleeve.

[noone1569]

Will do. thanks!

[Jbaker229]

I have yet to get into the fuel purge valve for my bike. I have noticed some odd behavior when it comes to fuel pressure, when the bike is cold the fuel pressure drops rapidly, but the bikes start just fine, when the bike is warm, the fuel pressure stays around 400-500kpa but the bike will not start.

Giving the bike a bit of gas helps the bike start when hot, but sometimes it backfires through the airbox.


Mackja what is the production number of your bike?

[mackja]

Mine is number 116. I still have the problem not as often as before. I am thinking about replacing fuel injectors, but I dont want to just swap parts. I sent a video to EBR of the hard start happening while at the track, so far they dont have an answer, but said they will continue to work on the issue.

[Jbaker229]

Mine is number 116. I still have the problem not as often as before. I am thinking about replacing fuel injectors, but I dont want to just swap parts. I sent a video to EBR of the hard start happening while at the track, so far they dont have an answer, but said they will continue to work on the issue.


Thanks, mine is 135 - interesting both our bikes came from the same dealership. I also sent them some of the onboard telemetry as the bike was starting, i am beginning to think it is the rear injector that may be toast (the non-showerhead injector), I often get an error for the rear 02 sensor when I am having the issue.

[Jbaker229]

Thanks, mine is 135 - interesting both our bikes came from the same dealership. I also sent them some of the onboard telemetry as the bike was starting, i am beginning to think it is the rear injector that may be toast (the non-showerhead injector), I often get an error for the rear 02 sensor when I am having the issue.

EDIT: upon further research the injectors being off is unlikely as it would cause very hard running, if the injector was leaking the bike would be hard starting when cold. I only EVER has this issue while the bike is hot. A clogged injector would cause the bike to run poorly while underway, so much so that you may loose a cylinder at idle.

There is a sensor near the airfilter that was slightly out of place when I opened up the airbox, Dan alluded that something may not be connected correctly in there, but I do not speak engineer so I was a bit vague as to what he was talking about. The sensor sits right on top on the airbox right near the filter, I am wondering if this is the culprit??

[d_adams]

The sensor sits right on top on the airbox right near the filter, I am wondering if this is the culprit??

Air intake temp sensor if you want the correct nomenclature.

[mackja]

Nope air intake sensor is not the problem, although when it fumes ignite in the air box it can melt and set a code, ask me how I know!! lol

[Jbaker229]

Ha, I am slow, the airflow sensor makes no sense.

I am thinking that it is an issue with the intake tract. Mackja - what happens when you get your bike really hot, and try to start it with the airbox cover totally off (exposed throttle bodies)?

[mackja]

Don't know, have not tried, but I would think the issue would not be their because any residual fuel or fumes (which seems to be present during hard starting) would evaporate rapidly.

[Jbaker229]

Don't know, have not tried, but I would think the issue would not be their because any residual fuel or fumes (which seems to be present during hard starting) would evaporate rapidly.

I do not know about your bike, but when the fuel tank is hot it is venting out fuel from the top vent which in turn goes into the built in charcoal canister inside the airbox. The canister then vents to the purge valve then down a hose to the intake manifold where the gases are consumed while running. With the purge valve always opened when stopped there are fumes building up in the intake tract.

My dad, who has 8 times more mechanical ability than me (thanks dad!), routed a vent tube from the charcoal canister out the airbox and down through the frame through the ground. For now it looks like the bike is starting correctly, I will take it for a long ride this weekend and let you know if it worked. Perhaps this might solve your problem as well?

[mackja]

I believe I have found the problem, I checked my charcoal canister and the glued seal around the top was not sealing, when the engine gets hot and fumes are venting into the canister fumes would leak into the airbox, this will cause a rich fuel mixture and the hard to start condition when hot. I thought I checked this previously but I just missed it. I have sealed the top lid with epoxy, hopefully this solves the issue.

[Jbaker229]

I believe I have found the problem, I checked my charcoal canister and the glued seal around the top was not sealing, when the engine gets hot and fumes are venting into the canister fumes would leak into the airbox, this will cause a rich fuel mixture and the hard to start condition when hot. I thought I checked this previously but I just missed it. I have sealed the top lid with epoxy, hopefully this solves the issue.

Excellent, let me know if it works!

[jdubxb]

I will need to check the canister thing as well as maybe the purge valve. I recently had two episodes of difficult starting when the motor was hot. It cranks and cranks but does not fire. The first time it happened, the fan started blowing as soon as I turned the key. Motor would not start after several tries. I tried holding the throttle WOT and that almost made it start; doing it again caused a backfire. Just when the fans stopped, I hit the start button and it fired up and I rode away. Not sure if it was just coincidence or if the fans being off was a "requirement" for starting.

The second time, the bike had been sitting for about 2 hours, no fan came on when key inserted. I don't remember clearly, but after several unsuccessful tries, I decided to hold at WOT and I think that is what got the motor running. But it also popped a "fuel pressure sensor" fault code. Unfortunately, I deleted it before riding off and I don't remember the code. The engine light was lit for the entire 45 minute ride home. The dash showed no fault codes were stored after I got home. The bike started up fine the next morning with no engine light.

I also checked the pins on the fuel pump connector (suggested on another thread) and they appeared fine.