Difficulty starting car when cold

Nov 10, 2004 4 Replies

I have a 1991 190e and I'm having difficulty starting the engine in the morning. I have to crank for a while. When it's warm, it starts right up. Any ideas? In the morning when I have a hard time starting, there is a small bit of white smoke that I haven't noticed before.



thanks


It sounds as if the cold start valve isn't working (properly). This is the fuel injection equivalent to the old fashioned 'choke'. It ensures a richer (more fueled) mixture gets to the engine when it's cold. As there's no problem with warm starts I would look into this first. You don't mention which type of fuel injection your car has.

The cold start valve is pretty much just an extra fuel injector. When the car is cold and running check to see if there is power to this cold start valve, if there is, then pop that injector out and check to see if it is spitting out fuel. If there's power but no fuel - duff injector. If there's no power start by looking at the temp sensor for it and stuff like that. Mike Disclaimer: Petrol is dangerous, don't any of the above if you aren't completely comfortable with your skills under a car bonnet (hood). W126 300SE 234,000 Miles W115 220

Adding to this good description, there's a temperature sensor and a thermo / time relay. The temp sensor is On / OFF at about 65 degrees and the time relay is also temperature related - colder is ON longer, but the relay is ON for perhaps ten seconds, not minutes. Then one comes to the electro-mechanical cold start valve mentioned earlier.

It's a chain and any link can be bad but first check that everything is plugged in! Trace the wires back from the cold start valve.

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