EHA is for enriching during acceleration, dont think it would prevent your car from starting. After it starts, if EHA is not working, you will not get a good throttle response. If you can rev up your car to 5000 rpm once it starts, it is less likely to be the EHA.

The most critical part is the cold start valve. Is it an electromechanical valve like mine on a 87 260E ? If it is, then it can be tested. When you turn on ignition, you should get a voltage (about 10-11V) on the valve's coil. If there is a voltage, you can remove it and then see if it sprays gas when you try to crank. I am suspecting it is not working and that would explain why putting gas in the intake makes it start and then all is fine after it starts.

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Saumil S. Patel