Somtimes when I shut the engine off on my 84 300d, it will continiue to idle. I can take out the key and still drive it around. Finally it will get a lower and lower idle and finally shake and turn off. Whats up?

Whats your brakes like? are they ok? do you get pressure buildup when you turn the engine over while pressing on the brake pedal?

if your brakes are crap then its a vacume leak.
check the vacume line from the brake servo to the entry by the fuel filter. then check the little elbow joint that comes out the valve in the brake - engine pipe. Tiny pipe reddish brown on mine. pipe runs to back of engine. joins up with a white pipe.

Check the one way valve on the vacume pipe. you should be able to blow in it the way of the arrow but not the other way. if you can then its fubared and you need a new one.

Turning the key to switch off the engine causes a vacume to the fuel pump. if the vacume is not there then the pump continues to run thus engine still runs. but the fact that you have disabled the electrics. the ecu and all electrical items are unavailable to control the engine. therefore the engine dies.


I only know this coz i put my one way valve on the WRONG way. drove 15 miles with ROCK HARD brake pedals. (scary on highway!)

Got back home and fixed this. then forgot to connect vacume line to brake servo. started engine and your situation came to light. fixed this and everything was sorted.

hope this helps.

probally a vacuum leak or shutdown unit. it uses vacuum to turn the engine off.

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toy list:
82 300sd----244000 miles
98 dodge ram quad cab 4X4----190000 miles
93 buick lesabre----216000 miles
71 pontiac lemans sport--tmu

The IP shutoff valve is suspect. You can get that for anywhere from $40 to $140, there is a special precaution to take when changing it to avoid run-away engine. I did mine, it was fairly easy. Do it now before you get oil in your vacuum lines. you can easily figure this problem out with a Mityvac.
All the instructions are here in the forum, read carefully before diagnosis and replacement.
Use the search engine for IP (injector pump) shutoff valve.

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Think Alternative Energy!
300CD '80 (now gone but not forgotten...)

try reving it and then turning it off. this willl tell you if its a vacuum leak

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Lock the driver's door, and then shut it off.

If it stops, then it is a leak in the locking system.

JCD

http://www.peachparts.com/shopforum/showthread.php?threadid=73871&highlight=engine+wont+shut+off