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Hard to start and keep running when cold.

I rode down to Virginia in two days. Last Saturday morning it was about 28F degrees in the VA KOA campground I was at. When starting, it wouldn't keep running without adding throttle. Eventually I was able to leave and ride, but at low revs there was no power, so I had to keep the revs up to move. When warm it seemed to be running OK but about 20-30 minutes later it would bog down while accelerating at highway speeds. The bogging lasted maybe a minute or two and then it rode great for the rest of the day while putting on maybe 250 miles.

On Sunday morning it was about 23F and time for the two day trek home. I had the same problem, but revved it a lot before taking off. Once warm, it ran perfectly again riding from Natural Bridge KOA to Altoona PA. I was thinking that it was just a cold weather thing.

Monday morning at about 22F, I had the same experience, but also puked a small 3" diameter puddle of coolant onto the ground, and again it ran perfectly for the rest of the day with no coolant leaks or any other problem.

Today, I just started it in the garage at well above freezing, and had the same problem, rough idle, and died without throttle, so I turned off the ignition.

My FJR is a 2008 model with 80,000 miles. It's just due for another valve check. Spark plugs were changed at the last valve check. Coolant is due to be changed. Air filter was checked and blown out a few months ago.

On all days, the check engine light would come on. I would turn the ignition off, restart and the check engine light would stay off. There are no error codes showing on the meter display. On all days it would eventually rough idle at 800 rpm, and later when warm, at the normal 1100 rpm.

I was wondering if I had some bad gas, or water in the tank, but I have run several tanks of gas through, since Saturday morning.

I hope someone here can lead me in the right direction to solve this problem.

Could be some bad fuel clogged an injector. Try some injector cleaner, like Seafoam, and see if it helps.

I woulda guessed some water in the fuel at first, but not now. Start with the MAP sensor.... check the hose going to it, and clean it with a pipe cleaner. Check there's not greasy stuff blocking the port in the MAP sensor itself (comes off with 2 screws).... See if that fixes it.
Vacuum leak? Check the hoses and TBS caps are all connected. Your TPS switch might be acting up (won't necessarily show a code, and may indeed test good when it's not). Was the coolant temp normal/OK (not low) throughout all this?
I'll venture that the coolant puke was not related, but I don't know why it would happen.

The coolant temperature read as normal when hot, four bars.

That's your bike telling you its too frikin cold to be riding!


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bobrider wrote:That's your bike telling you its too frikin cold to be riding!


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I'm not listening!

I had time to look at it today.

Following Rayzerman's advice I took the vacuum hose off the MAP sensor and peeked inside the line and the map sensor, see picture.



Well, there was nothing to see, so I put a long thin screwdriver into the hose, and out came a small bit of thick oily goop, stuck to the screwdriver. I didn't think it was that much so I had little hope, but I persisted and took off all the vacuum lines (lines with a grey stripe) from the throttle bodies, but kept the assembly of hoses together . I then sprayed WD40 through the lines to dissolve any thing that could be in there. After that I blew the lines clear with compressed air.

I put everything back together, hit the starter button, and right off it just purred like brand new, not a hint of a problem anymore.

You da man Ray!

Kick ass