Have you checked the timing? It's electronic so there's not too much to adjust...and I am a points guy, so I con't tell you how to do that, but when I hear backfire, I start thinking about timing.
I don't think the float valve is likely to be the problem with at least getting it to fire correctly, but it could be an issue with getting it to run smooth down the road. I wouldn't worry about it at this point unless gas is overflowing.
I don't think the float valve is likely to be the problem with at least getting it to fire correctly, but it could be an issue with getting it to run smooth down the road. I wouldn't worry about it at this point unless gas is overflowing.