'94 C200 is difficult to start, in a warm climate.

Ignition timing is controlled by ECU, battery is in boot so can't get hot, so I believe the cause is injectors are too hot & nozzles are clogged by wax, like in my '90 Accord before 2-10 when I replaced its injectors' resistors with a buck convertor & 5 inductors & 1 diode & 6 capacitors. This C200 's coolant's max tmprtre could reach 96ºC when under a hot sun & 5 users inside are cooled by aircon. I removed the bow shaped rubber lining under bonnet, to let out hot air, then max tmprtre was 90ºC with 5 users cooled. Does any1 here know whether this C200 's injectors' voltages ( I presume ~ 4v ) are fed from resistors, or a buck convertor ( maybe inside ECU ) ? Is a circuit diagram of these injectors & ECU downloadable ? Is this C

200 's coolant's ideal tmprtre 80ºC like BMW's ?

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Majority of the time in difficult fuel injected warm start condition during hotter seasons... such as spring, summer and fall... tt is because of leaky fuel pressure leak.

With pressure reduced to nothing on a hot summer day, the liquid fuel turn into vapor... hence vapor lock.

There are a couple of places to leak... fuel injector... which usually can be found by looking at spark plug... if it is fouled... that is the leaky one.

Another place for leak is the fuel pressure regulator and the last place of possible leak is fuel pump checkvalve (this checkvalve can be several different type... one is simply check valve... other is like fuel accumulator). This is all assuming you got zero fuel line leak

This last two is easily diagnosed with fuel pressure gauge.