Bike won't start. Where do I start?

[WinterHack]

Hey all!

So my 2006 winter hack wouldn't start this morning. Starter turns over, but engine won't start. I did have an almighty backfire, but wound up draining the battery for trying to many times.

I've pulled the plugs, and I do have spark, so that's OK.

The bike has only been sitting three days since the last time I rode it. It's always started within seconds of pressing the button.

I am thinking maybe there's some crud caught in the fuel line? Though, it was running fine three days ago.. Would that be enough time for all the fuel in the carbs to evaporate?

I don't know if it's related, but the reserve doesn't work. I went 230 miles, switched it to reserve, and had to push it most of the rest of the way home... Suggests crap at the bottom of the tank, maybe? The tank is half full now, though...

Anyway, I've got the day off work tomorrow, so am wondering where I should start to figure this out...

Thanks in advance!

[Rallyfan]

I'd start by ignoring the problem. Set fuel to Prime, choke on, and try it.

Next I'd see if the fuel switch is OK, if there's crud etc.

[WinterHack]

Yup, I tried switching to Prime, no luck.

I'm thinking fuel switch too. As I said, my reserve "doesnt work", so I think there may be a lot of crud in there somewhere. When it ran out of petrol a few weeks ago, I was able to "limp" it home; ride it a hundred meters or so, push it for a bit, ride it for a bit, push it for a bit. It was like fuel was getting though, only *slowly*...

Should I be checking the petcock, or the filter?

[MeeLee]

Yeah, unplug the drain hose, and see if the fuel flow is obstructed or not.
Also check the air filter.

If the fuel flow is good, try to drain the carbs. It might have some crud in there as well.
Most common is clogged jets.
I don't know if you could inject some acidic stuff in there, to dissolve the junk.
I remember a guy putting his jets in a coke can for a day, they came out sparkling new!

[NakedTwins]

I've had similar problems as you mentioned. First clean your carbs and inspect your Jets & all fuel passages are clear of debris. Second i would completely bypass the fuel petcock by running a fuel hose directly to the carbs. (This may inadvertently identify a potential problem with your petcock delivering fuel) I achieve this with a Corona bottle filled with fuel, rubber stopper with a hole drilled through it lol. Try to start the bike while adjusting your choke to its 'sweet spot.' My GS500 loves to be at 3/4 full choke when cold. If you can, make a video recording troubleshooting tests.

~~ Ciao!!

[WinterHack]

Thanks, all, for the advice. I went out to figure out the problem yesterday, and the bike had magically fixed itself. I am guessing there was some crud somewhere, that's worked itself loose. No doubt it will re-crud when I'm late for work, but for now I'm not going to disassemble anything.

Are fuel additives any good for keeping the fuel clean?

[MeeLee]

Yes, however...
I would install a fuel filter first!
Sometimes adding a cleaning agent in the fuel can make the corrosion in the tank come loose in the fuel and clog the jets much more.

Seafoam is your number one fuel cleaning agent!
Chemtool B12 is also good; works better on hard starts, as it actually adds power to the fuel, unlike seafoam that is just a form of oil that doesn't combust very well.

B12 is more aggressive than seafoam, and I'd only recommend one tank of B12, after which seafoam is a great alternative!

[Janx101]

Once the tank of fuel cleaner stuff is used. .. then take the added fuel filter out again! .. they seem to be problematic long term