Sorry my search didn't work so I'll ask.

1989 300CE

I have now on two occasions had the car not start after it was hot and shut down. Continued cranking results in the occasional back-fire out the intake. After leaving the car alone for a while (15-20min.) it starts right up and runs fine. At his point I'm guessing fuel pump relay or fuel pump. Correct? Any way of testing these components? Thanks.

Jorg