したら?

The sentence is, 誠は言いだしたら全然人の話を聞かない。 It's an example of a -だす usage, but I've never heard する conjugated as したら [which is where the だしたら is from]. What does it mean?? I looked it up and the best i could come up with was 'try to' [so, "when makoto tries to talk he doesn't listen to what other people say at all"] but I'm not sure that makes sense.

sorry i post so many questions ;-;

~たら form of verbs is a "conditional" (can be either "if " or "when"). だしたら isn't itself from する、it's just a conjugation of 言い出す which happens to look the similar to the たら form of する

There's no sense of "try to" here. When he starts talking/comes out with an idea, he won't listen to what other people have to say about it.

oooh O: i thought that it was somehow connected to する. thanks for clearing it up, and for answering my question. you're really helpful :'D