Hmmm.....just guessing here..but my 85 VW westfalia had the exact same problem. It didn't like to restart when it was warm. It would restart sometimes but not always. It had tons of cranking power, but no start. I replaced my fuel pump and fuel injection relays. I also replaced a crusty vacuum hose on the fuel pressure regulator that i suspected was leaking. I'm not exactly sure which spot was the weak link, but it starts up everytime now! My first thought was that it was a spark problem, but now I know it was a fuel delivery problem. Good luck!