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Discussion Starter · #1 · (Edited)
Engine shuts off when idling after start/restart. (2012 CBR250R)

Here's the scenario: I start the bike and ride it like normal. I get to where I'm going, turn the bike off, and do whatever I'm doing. I come back out and start the bike up. About 5-10 seconds after starting the bike up, it idles so low it cuts off. I restart the bike and it holds a steady idle at the normal 1,500 RPMs and behaves fine after that.

It's done this in warm weather, cool weather, and with regular, mid, and high octane gas. I'm keeping notes on this to let the dealer know when I take it in for the break-in maintenance. Have any of you had this problem, or have any idea what could be causing it?
 

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Engine Quits Operating on Restart.

Greetings Rusty Shackleford,

What you are experience with your cbr on a restart after sitting, after engine has reached normal operating temperature.

After the ignition key is turned to the off position. The engine goes thru what is known as a heat stabilization cycle. All of the engine hot spots, Combustion Chamber, Exhaust Valves, Exhaust Valve Seats, Exhaust Valve Guides, Exhaust Header Pipe and also the hot coolant inside the engine's cooling system.

Remember that heat travels to cooler temperature. Until all of the combined components are at the same temperature.

Sitting above the cbr's engine is the Fuel Tank, with the electric fuel pump install in the bottom of the gas tank. This unit is close to the engine's Cylinder Head, which containes all of that Heat.

All of the gas lines are a type of plastic, which absorbes the heat from the engine.

Liquid Gasoline, can turn to a gas vapor below 32 deg F.

The Fuel system that supplies gas to the Fuel Injector is known as a Dead Head Supply System. What this refers to, is that there is only one gas line to the Fuel Injector from the Fuel Pump Assembly.

As the cbr's engine goes thru the Heat Stablization Cycle. The Liquid Gasoline that is inside the Fuel Injector and connecting Piping start to absorbes the Heat. The Liquid Gasoline, if it absorbes enough heat, will transform into a gas vapor. This will create the Condition, Known as Fuel Vapor Lock.

When the cbr's engine starts the first time. There is enough Liquid Gasoline to start the engine and then the Fuel Vapor Lock is injected by the pulsing injector and the engine quits operating (Dies). When the cbr's engine is restarted. The Fuel Pump Assembly will supply Liquid Gasoline to the Fuel Injector, Forcing the Gas Vapors to pass thru the Fuel Injector. Once the Fuel Vapors has passed thru the Fuel Injector and now the Fuel Injector has a Supply of Liquid Gasoline. The cbr's engine starts and operates in a normal manor.

This type of Fuel Delivery System won't be found on any Motor Vehicle. The System used on Motor Vehicles is known as a Constant Bleed System.

This type of System has a Return Hose to the Gas Tank. This is one of the reasons that the Fuel Pump is turn on for 2 or more seconds wheneve the Ignition Key is turned to the ON Position. This will Force any Fuel Vapors that may be in the Fuel Rail to the Gas Tank and supply the Fuel Injectors with Liquid Gasoline.
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Interesting post Soul Searcher (I'll have to remember that).

Rusty, out of interest, if the above is true, shouldn't giving it a bit of gas/throttle on startup (in neutral of course) let the engine rev higher (only by a few hundred rpm) for a few seconds and let 'good fuel' into the injector? Maybe the engine just needs a little 'help', until it can run smoother? I know I always wait until I hear the fuel-system complete its 'power up' before trying to start the bike as well.
 

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Do you turn the key on and let it sit for a few seconds so it has a chance to prime the system? I don't touch a thing until after it goes through it's little check and the fuel pump humming is done. That should prime the system and get rid of any vapor in the line and knock on wood I've never had my bike or my wifes bike shut off after starting them. I did see somebody else on here post the same exact problem you're having though. Not sure what the outcome ever was though.
 

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Time Heals All.

Rusty,

This Fuel Vapor Lock is Time Sensitive. Once, all of the components reach the same Temperature. Some additional components, such as the Fuel Delivery System, goes thru an unusual condition.

The Fuel pipe from the fuel pump assembly to the fuel injector is filled with Liquid Gasoline and Gasoline Vapors. This pipe is normally pressurized to 43 psi. During the Heat Stabilizing Cycle. When the liquid gasoline turns into a gas vapor, the static pressure inside the pipe Starts to Rise.

The Fuel Pressure Regulator is incorporated inside the fuel pump assembly. This keeps the fuel pressure at a constant pressure for the fuel injector. When the pressure inside the pipes starts to rise. The excess pressure is released back into the gas tank thru the fuel pressure regulator.

As the Heat Stabilizing Cycle start cooling towards ambient temperature. The gas vapor bubble in the fuel pipe will start to decrease in size. If enough Time passes. The gas vapor bubble will disappear completely.

When the next time the Ignition Switch is turn to the ON Position, the fuel pump will turn on for 2 or more seconds. This will repressurize the fuel pipe with Liquid Gasoline and a Normal Start of the Engine will occur.

When you experienced this condition with your cbr. It was somewhere in the Heat Stabilizing Cycle. You happened to be the Lucky One that this has Happened to.

If you experence this condition many times. I would suggest that you take the cbr to a Honda Dealer. What you need is a record of the operating conditions when this complaint happens. With enough details so the Dealer can verify the Complaint.

If this complaint occurs many times. I would suspect the Fuel Pump Assembly as being the failed component.

When this starting/running condition occurs. Just use the normal start procedure.

Do not apply any throttle.

When the cbr's engine quits operating. All of the oil doesn't remain in all of the oil passages in the engine/transmission. There are many clearance passages that the oil will drain out. All of the components will have an oil film left. The top most components is the camshafts and valve train components. There is two oil circuits that feed each end of the camshafts. All of this oil will drain back into the engine sump.

When you start the cbr's engine. The engine is rotating at about 400 rpms, when the engine starts. The idle is controlled by the ecm. This procedure will ensure that an adequate oil supply is supplied to all of the engine/transmission components.
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Discussion Starter · #7 · (Edited)
Okay, so it shut off during start-up idle this morning (Monday 04/30/2012) without being driven for 3 days (Friday 04/27/2012). I'm not sure why this would be the case. It doesn't usually happen under that condition. Like before, when I restarted it, it idled perfectly normal and ran fine on my drive to work.

Also, I took the bike to Honda on Friday after work, hoping the problem could be easily replicated. It couldn't because the bike was still at operating temperature from being ridden up there. When I take it in for break-in service, I'm going to really emphasize this issue. It literally does this 1/3 of the time when I start the bike.

Would it possible for the problem to be vapor lock when the bike is completely cooled down?
 

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Hello, I am getting this problem also for the last 4 days.
I ride my bike every day. When i start up my bike in the morning (temperature is around 5-12 °c) it starts then runs for about 5 or so seconds the just cuts out. I turn it all off then start the start up sequence again, start her up and she runs like there was no problem.
Dealer said to give it a bit of throttle and it looks like it is working.
But just this afternoon after work it looked and sounded like it was going to cut out again but i gave it a bit of throttle and it stayed running.
It only does it when i go to start her and she is cold.
By the way it is not far of to winter and it is getting colder, i had her all summer and have 6500km and not one problem until the last few days.
I might drop her of to the dealer one arvo so they can start it in the morning to see if there is anything wrong.
I will keep an eye on this and if i get a soulution to my problem i will post.

Thanks.
 

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I had the same problem happened to me after work yesterday, first time. Started it up and it was idling pretty weak then it shut off. I restarted it, gave it a little of throttle, it was fine. Again, this was the first time it happened and my baby only got about 450 miles on her. It's still in the breaking in period so I am not too worried about it, but I will mention it to the dealership when I get the 600 miles service and keep you guys posted if it keeps happening, hope not!

Keep on truckin!
2012/Tri-color CBR250R
 
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Quick question, anyone using NON-Ethanol gas????? I had this happen for one tank, thought i would be nice to MY bike and went down to the local SHELL and put in some of the NON-Ethanol gas and guess what? She would stall every single time i started it up after it cooled down. Decided to put the E10 back in her and has not stalled once since then.

Guess im stickin with the E10:confused:
 
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