Originally Posted by ShawnQ
There have been a dozen or more times when the car will crank all the way through it's cycle (which I believe is 8-10secs) - at this point, the car realizes it is not going to start and then shuts off the starter. Try it again, and it fires right up - everytime this has happened, no problems starting on the 2nd try.
I always hear the CPS issues cause a car that wont start at all, and wont stay running. They also say the car stalls. This has never happened, however it could be on the horizon I suppose.
The fuel pump definitely initiates when the key is in the 'on' position - no problem there. However, there is a check valve that holds pressure in the lines when the car is turned off. This supposedly prevents the fuel from returning to the tank when you shut the car off, and allows quick fuel when you hop in to start the car. This is prone to leaking on the SLK32's from what I've read, which causes hard starts.
CHECK VALVE OPERATION
The electric fuel pump outlet contains a one-way check valve to prevent fuel flow back into the tank, and to maintain fuel supply line pressure (engine warm) when the pump is not operational. It also is used to keep the fuel supply line full of gasoline when the pump is not operational. After 30 minutes the fuel pressure may drop to 2.5 bar (36psi), but the liquid gasoline will remain in the fuel supply line between the check valve and fuel injectors. When the fuel pump is activated, the fuel pressure should immediately (1-2 seconds) rise to specification.
Abnormally long periods of cranking to restart a hot engine that has been shut down for a short period of time may be caused by either fuel pressure bleeding past a fuel injector(s), or fuel pressure bleeding past the check valve in the fuel pump. "
Seems to make sense...
SQ