My 450 SL wend from a dream to drive to a cripple after truning a corner and not being able to gem more that 1000 RPMs. There was slight overheating coaxing it home but not to boling. I tried the fuel flow test (1 liter in 30 seconds0 and the flow is right.) I loosened a fitting at one injector and fuel is there too. The cam and crankshaft both line up on the 0 markon the pully and notch on the cam carrier at the same time and ignition is showing to fire at or near TDC. There is spark at the plugs but I can't even get it to fire now. Does any one have any suggestions? Could the catylic converter be plugged???

 

You don't mention age/mileage etc.
The suddenness of this problem suggests that it is something relatively simple although finding the problem may not be so easy.
Since you state there was some overheating this suggests the engine is running very weak or is firing at the wrong point.
Not familiar with 450SL so don;t even know if it has electronic engine magement. if it has do you have any codes/warning lights?If electronic I'd suspect "limp mode" (Should start and idle fine but revs and gears changes limited) then have a look at the crank position sensor (might explain reluctance to start) them the electronic accelerator/throttle valve.
More data might narrow things down a bit
Stuart

 

Age? I'm 66. No the car is a 79 with 113,000 miles. The timing chain was replaced around 100K. It has electronic ignition and mechanical fuel injection. I'm not sure if there is a pickup on the harmonic balancer, but I'll certainly check both visualy and in the manual I have.

 

I couldn't find any pickup associated with the crankshaft. I tried putting a small amout of gas directly into the intake system but still it won't fire. I checked the spark at the plugs and it was there good and strong. Any more Ideas?