I have an 89 190e 2.6 and I had the same problem when my car sat for a while. Turned out the cold start valve was gummed up. Put a fresh battery in it so you can crank it over and when you try to start it, hold the gas pedal to the floor for about 5 seconds while cranking it and then let off. When you let off the gas while cranking, see if it tries to start. My problem was due to my gf putting regular gas in the car instead of super. Changed the valve and it starts fine now.