--- In st2_owners@yahoogroups.com, "Stephen" <ssellars@...> wrote:
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>
>
> Hi Phil
>
> I've got a 1999 ST4 down the road from you here in Raleigh that just contracted the problem you seemed to have suffered.
>
> I was heading the the biker breakfast over in Pittsboro this morning and the bike stalled at a light, then wouldn't start again. I get the sound of the fuel pump starting and it cranks fine, but won't fire up. It's been stalling occasionally in traffic, but was running great at speed and previously would always start again on first press of the starter button.
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> This was the first day running it in a couple of weeks, so may try adding fuel stabilizer first? Fired right up when cold this morning.
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> Any suggestions?
>
> Thanks
>
> Steve
>
Hi Steve,
More has transpired since my last post.
I found my source of intermittent rough running- vapor lock! You may want to look into this- stalling in traffic could be from engine heat creating gas tank vapor lock- fuel isn't supplied because air cannot enter tank to replace it. Most likely happens with a full tank (less air volume) and a hot engine (the heat may close off marginal venting). Here's my story:
I had a great ride on the Blue Ridge Parkway. On the way back, I stopped and got gas since I'd been running w/the fuel light on.
The next morning, I started out for another ride. I warmed the bike up, as usual. I hadn't gone 1/2 mile before the motor started running rough again.
I returned home and checked the usual culprits, spark plug wires, voltage, etc and pondered it the rest of the day.
What was different from yesterday's great ride? I filled the tank! It was too quick to be "bad gas".
To test my vapor lock theory, which is more likely with a full tank, I went for a ride until it started missing and losing power. I pulled over, opened the tank, and closed it. I was able to ride a good bit more before it started again. This time, I pulled over, opened the cap, and left it open (don't try this @ home). I was able to ride up and down the long straight road in front of my house- no problem.
I looked at the gas cap assembly, but could not find an obvious restriction.
I took the assembly apart (don't try this either- it has springs and stuff in it!)
The thing I like about digital cameras is taking pix while you take things apart- I do recommend this!
Anyway, I still couldn't find an obvious issue, other than the rubber boot between the cap and tank that allows air exchange. It was a little soft and deformed. It could be pinched if the cap isn't closed carefully. I drilled out the vent hole a little bit to get better mating.
I went for a ride after that. Ran great w/o any hesitation- problem solved.
That is, until I looked at my voltmeter and saw 16+ volts!
TBC.....
Phil
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