1992 190E Won't start when hot.
 

This is a new car I just bought so I don't have any history. I determined that the fuel pump cuts out after a couple of seconds starting it when hot so it won't start. I jumpered pins 9 and 7 in the fuel pump relay, now it starts and runs fine. Pin 12 is labelled crank rpm and I have no input from that. Is this the crankshaft position sensor? Does that sound like the problem, and how hard is it to change? Is it under the engine? Any help would be appreciated.
Thanks

If the crank sensor was the problem the engine wouldn't start even with the fuel pump relay jumped!

That signal is from the EZL (ignition module), it takes the crank signal (AC sine wave) & processes it into a DC (square wave) signal.

190e won't start hot
 

Thankyou - so does that take me to the ignition module being bad?? I can't find anything telling me how to check that input- or am I headed up the wrong path.

Thanks