I just bought a matrix like 2-3 weeks ago and now every time i get abou half a tank through it it will stop and i can't get it started agin.
Even if i prime it, it will only run for 2-3 seconds.
There is some bubbles in the fuel line when i look at it.
It will run again if i let the engine cool down.

Whats my problem?

Same I problem I am having. Posted the same question earlier and have had no replies. I thought about the fuel lines getting to hot. What about you? Have you tried to re route the fuel lines? Otherwise I have no problems. If I find an answer I will let you know. Good luck.

i can't figure it out

I have re-routed the fuel lines on my Matrix. I did it because I do not like my fuel lines to wrap around the engine head. You probably have a air leak some place. Air leaks can be a "*****" to find. If you can not get it worked out, simply call Cen and send in your buggy with reciept. I'm sure they will take care of the problem. I know that may take a week and half out of your rc fun, but it can eliminate a lot of the headache.

I had the same problem and found it to be a slight split around the tank join after I replaced it and used AT fuel no problems since.

Steve