Need some input on a stubborn problem that is becoming very annoying. I have a 1985 500 SEC, only 215,000 and runs like a top.

However, the engine is ususlly VERY stubborn about re-starting after sitting 10 minutes to 3 hours. First thing in the morning, fires right up, regardless of temperature, after it sits all day at work, fires right up, regardless of temperature, if driven and shut off, say to fill with fuel, fires right up. But, give it 10 minutes and it is very difficult, skipping sometimes on more than one cylinder, sometimes requires re-starting, seems to be flooded. Once started, rev to 1500 or so, it clears and smooths out and runs fantastic.

I am open to suggestions? Thanks in advance.

(Also, sometimes when it is tempermental like this, the fuel pump sounds like it is cavitating, this usually abates in a few moments, but not in sync with the smooth running of the engine.)

may be the fuel pump check valve. have it checked...

Alon

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'92 300CE - Sold
2004 C240 - 744 - C7 Wheels - Android Radio
2002 C320 - 816 - Sport Wagon

Hi Mark,
I'm not familiar with the 300SEC, but your symptoms are indicative of a flooded engine. Try depressing the throttle about halfway down when it doesn't start and see if it doesn't allow the engine to clear itself more quickly. Your fuel pump noise is probably due to the fuel having lost pressure and taking a little time to pump it back. You might possibly benefit from one of the snake oil fuel injector cleaners... possibly not, also.

Good luck with it,
Richard Wooldridge
'82 300D/4.3L V6
Etc...