Hot start problem 92 190e 2.3
 

After a good cold start my 190e 2.3 takes 5 or 6 tries to start after it gets hot but sometimes can take up to 3 hours before it will start. Problem worse in summer. Runs good when it does start. I was thinking it might be an elec problem but something I did last time makes me wonder if it is fuel. When I took the fuel line off of the injector module there was no pressure, i.e. no fuel squirted out until I keyed on, then a stream a couple of feet. So, vapor lock seems possible but for 3 hours? Any help?

try to start it when it won't and see what's missing. no spark or no fuel. could be a number of things-fuel pump relay, crank sensor, ezl unit, low rest pressure(unlikely). vapor lock is not an option if the fuel pump runs when it's supposed to and the accumulator and/or fuel pump check valve is/are doing the job. no 1 item sticks out. you need to test. good luck, chuck.

From threads I have seen posted on here it points to the way a CPS does when bad. It would be a definite one to test.

Will do some tests soon. Now I have wiring diagrams and a meter in the car.

I think rebe has nailed it. My 300E had the exact same symptoms. A used sensor out of a 180 fixed it. Any sensor from a 4 or 6 cyl model Mercedes of the period should fit and might be a cheap fix for you.

You can check for a HOT spark output at any of the wires OR the coil wire.
Just open the gap on a regular plug OR cut the ground electrode off & see if the spark can jump to the case of the plug.

CAN also be the fuel accumulator!

Just now able to get back to the car. I have spark when it won't start hot. Also checked ohms of temp sensors and all are in range. Must be some kind of fuel problem. How do I tell if the injectors are leaking or if it's the pressure reg not holding?

To really know if the fuel pressure is being retained, you need a fuel pressure gauge.

However you can test the fuel accumulator w/o special tools.
There are several good write ups on that test.

The problem was getting worse - missing for 3 or 4 seconds when it finally started hot. I thought that might mean flooded so I bought new Bosch injectors but still same problem. I have found that it seems to start faster if I hold throtle to the floor while cranking. So, it has fire and new injectors, the sensors are within range but still seems to be flooded. What else could it be?

I would test the accumulator as others have suggested. No special tools needed.