I use to play with first person view (internal).
In some track the camera jumps to behind view just after star (when is a 3 seconds wait GPS), and when there's some stuff in TM like turn light on... This is anoying for me.
Is there any way to block my camera and avoid this jumps?

no.

I wouldn't have thought effects like the GPS countdown etc would switch the players camera angle. Sometimes the author will put a race camera as well as these effects which would cause this behaviour, but they shouldnt really. The MT should make no assumptions about which camera angle the racer prefers, and only force a certain view where it is neccessary - i.e. loops / corkies etc.

Agree.
But that's most of the times just now knowing how to use the mediatracker correctly. It rarely happens attentionally.

What you should do is to report such issues to the author and give tips how to do it correctly.

As newbie i like to ask is it correct that i cancel the gps with "camera race" & Default/Local Player ? Or is there a better way ?

I think forcing a camera jump always is anoying for other cams users. Don't know if there's a better way to do this...
Anyway, try to not place the "forced camera" in the middle of a corner, or just at entrance (when you're taking the outside to enter next corner)...

An empty trigger with no camera track at all is sufficient to cancel any previous MT.

Jonkster says:
An empty trigger with no camera track at all is sufficient to cancel any previous MT.

That!

In other words...
Add a new MT Clip, place that green box where the camera should go back to normal. Don't put anything in there, no effects, no camera, nothing.
You'll be fine.