94' E320 No Start
 

I have a friend with this car and she tells me the car would not start when she got off work. She says she can smell gas when she cranks it. I would think it might be ignition related. I was hoping someone could steer me in the right direction. I have never worked on any Mersedes cars. She has had this problem before and sad it would eventually start, but this time it would not. Where should I start? Spark test? Is the ignition switch a common problem? Anything else I should look at?
Thanks for any help
JohnT
ps: This is a gas motor, not diesel.

Should this be in the Tech Help section?