1990 Mercedes 420sel won't start
 

So I have this 1990 Mercedes 420sel with 200k on it that was running fine and then just stopped. Now it tries to start but doesn't - it seems to almost get there and then just can't get the last bit of vroom. It's getting spark and fuel, but not starting. I'm going to change the fuel filter but I'm not sure that will do anything, and it seems like the fuel pumps are working. What else could I try? I don't want to saw off the tail pipe and do things to the catalytic converter - but would that be the problem maybe? Any help would be appreciated.

What is the fuel pressure? (Measured with a fuel pressure gauge.)

Check the crank position sensor