Engine Wouldn't Start After Valve Checks and Other Maintenance

[dnktng]

Probably not the last time I'll have that sinking "oh crap, what did I do this time" feeling.
I had just fininshed the 16000 miles valve check (at 20000 miles), replaced spark plugs, and the o-rings under air cleaner housing. When reassembling everything I had got to the point where everything is back together mechanically & electrically.....gas tank on & filled, all wires connected..... ready to start. It fires right up & I let it run for 5-10 seconds, sounded fine, confident everything is good, I turn it off. All good so far.
Next day I install new undercowl, put all the plastic back on and park it.
2 days later I try to start it and the starter motor does its thing and grinds away, but no fire. That's weird, it fired right up 2 days ago. Here is what I think may have gone wrong:
- Maybe bumped a sensor wire putting on plastic, or possibly tightening gas tank down. But I didn't have any Malfunction Light (MIL?)
- I had drained gas into container that I thought was empty. Possibly it had some residual gas (and water in it) and when I poured it back in tank, water settled to bottom after 2 days, and prevented firing.
- Throttle cables got pinched or stretched causing throttle to be slightly open when installing plastic (especially left cowl pocket) and flooded engine.
- New oring under Air Cleaner Housing are creating a clearance problem when gas tank tightened down. This seemed pretty unlikely to me, but stranger things can happen.
- Pinched Fuel Line or air/vent hose.

So, I drained the gas out and dumped it in my old truck & got fresh gas for the NT. Took off plastic until sensor on the front of air cleaner housing was accessible. I was concerned about that sensor because the wires are so tight. Gave the sensor a giggle, and it was definately connected correctly. Dumped fresh gas in and cranked it over. After about 5 seconds of cranking I hear the engine try to fire. Re-crank it and slightly open throttle and it roars to life....mmm, didn't expect to get it started that easy. Restarted it a couple of times, put plastic back on, restarted it a day later and everything seems fine. Believe it must have been bad gas or water in my container, or the throttle was slightly open & flooded the engine....still not sure.
Took it for a 40 miles ride yesterday and everything seems great.

Glad I started it immediatly after the maintenance was done and it started fine then, even if it was for only a few seconds. It eliminated many potential problems.

 

[Coyote Chris]

Dan, I would say of all the things mentioned, flooding due to throttle body butterfly valve being partly open would probably not be a possibility with Fuel injection.
Unfortunately, the normal trouble shooting one might do is not too easy on this bike. Or many modern cars that are computer controled. Is there spark and is there fuel?
Not easy to tell with out taking things apart, which might fix the problem if a wire/connector connection wasnt making contact. I cant wait to other, more savey folk weigh in on this one.
One thing I am very careful with is draining fuel and then putting it back into my bikes....I would rather put the old fuel in one of my old vehicles and put in fresh fuel from one of my good
containers where I store my non-E-10 stabilized fuel. I think someone said there was an obdii connector? If the computer stores trouble codes, I think it would be worth the money to
by a reader and check that for your own piece of mind. Another question I have is, Is it a good idea to completely drain the tank? I have heard there can be issues doing that as the fuel pump
may take awhile to start pumping high pressure fuel to the injectors after a drain, but that might only be an urban legand.

 

[seagrass]

Draining the fuel should not be a problem as the fuel pump "primes" the system as soon as you turn the key to on. If you have the kill switch active (so the bike cannot start) the priming does not happen.

Do not ask me how I know this :redface:

 

[Bear]

Whenever I transfer fuel from a gas can to the bike, I use a funnel with a filter. They can be bought at any NAPA store for about $5.00. I also use it when I fill my gas cans at the pump an immediately treat the fuel with Star-Tron. I have had no Ethanol related problems with any of my engines--two or four stroke. Chain saws are particularly sensitive to Ethanol, and I have had no problems.

 

[Lorien]

FYI: it is possible to flood a Nt by opening the throttle. I did so about a year ago after as they say "further review". One day out on a day tour mine would not start even though it turned over. Could not find anything dumb until I remembered I had leaned on the throttle and slightly turned the grip while starting. It took about a minute of cranking and 5minutes of waiting before it fired very suddenly as if nothing unusual was going on. Very memorable as I was a long way from home. Has never recurred.

 

[dnktng]

Looked at the shop manual after everything is back to normal to see if there any more insight on the problem. Here is what I learned:
1) Chapter 24, Troubleshooting is actually a pretty good guide to start if problem recurrs. Eventually it sends you to the chapter that explains all the MIL and fault codes, chapter 6 IIRC.
2) I should have cranked the starter for >10 seconds to see if a MIL light & fault code would come up. I did not know that, but will try that if it ever happens again.

Thanks for the inputs. I rode to work last night & will get a chance to ride home in the morning. Not much too worry about unless it happens again. Starts fine now.