Dhouston you think it does not expect a rising edge while Bruce you are pretty sure it does.
When I read the manual info about PULSIN it looks like there is an EDGE detection...

The manual says that it waits for and EDGE, you're right but the I don't know how I am supposed to start PULSIN if I don't know when the EDGE will appear on the line and PULSIN has a timeout.

Something very weird:

To do some experiment, I've tested the code I've posted above (a polling loop). In this configuration, PULSIN will NOT see a rising edge but will start no matter what, so I assume PULSIN begins and runs until it sees a falling edge (which is not the way you tell me PULSIN works) or until the timeout happens because the pulse is too long.
I connected my application circuit to the tespin and I trigger my application circuit where I set the pulse pin HIGH at the begining of the code section for which I want to mesure the execution time then set the pin low when I reach the end of the section. This way, I expect PULSIN to tell me how long it takes to execute a section of a program.

I get a value of 14925~14927.
If I read well PBP manual, as I'm using a PIC16F684 (with DEFINE OSC 8) the resolution should be of 5US per iteration of the PUSLIN internal counter. Which makes 74ms.
What a surprise because in the application circuit in the section of code I'm testing, I use a 80ms pause, so the mesured execution length should be of AT LEAST 80ms...
How is it possible???