250SL Auto running rich

[cfm65@me.com]

Hi Guys,
Over the past few weeks, I managed to get my 250SL Auto running quite well and have biult up a reasonable understanding of the fuel injection system.
However, all of a sudden and without any provocation, it started running very rich. It is not the cold start solenoid or the cold start valve. Fuel injection pump oil level up to the line.
Any suggestions will be much appreciated.
Regards
Chris

[ctaylor738]

It sounds like you need to expand your understanding of the injection system to include the Warm Running Device aka the Won't Run Device.  The plunger may be sticking in the cold/rich position. Plenty of information on this.

Another possibility is a plugged fuel return line.

Cheers,

CT

[cfm65@me.com]

Thanks,
Your advice is much appreciated.
Regards
Chris