Strange no-start problem, 2000 SLK230
 

I have a 2000 SLK230 with 215,000 miles. Ran fine last time I drove, a week or two ago because of the ice.
Went to start it, you know how the car cranks automatically when you twist the key to start? Now, it very consistently cranks for about 2 pistons - about two seconds, and then stops cranking. Every time.
It sometimes starts like on one cylinder, bangs a couple times or backfires quietly once.

Plenty of gas. 45 degree air temp, not too cold. Gave it some starter spray, it tried to run on that for a second.

My best guess so far is that the computer is detecting no fuel pressure and turning off the cranking. I hear all sorts of humming that I assume is the fuel pump.

Put it on a battery charger, but that wasn't the problem. No Check Engine light.

Any ideas before I have to tow it to the dealer? Thanks for your help!

David

Key problem?
 

Have you tried locking and unlocking the car then try to start the car?
Have you tried starting using a different key?
It could be that the fuel computer is not receiving the start authorization signal from the ignition switch.

You are my hero! problem solved!
 

I had bought a new key fob from ebay and moved my key and electronics into it.
I just dug out the other key fob and it started right up. I must have screwed something up in the transfer.

Thanks team!

^my first thought too, drive authorization. Might get some error message in the odometer display window to confirm this.