Recently drove 100 miles with no apparent symptoms of engine malfunction. Ended short trip in my garage. Stopped vehicle with engine running. Engine began to run rough, deiseled, missed and acted as if had bad gas, vacuum leak or poor grade of gasoline. Immediately turned engine off. Turned ignition back on and checked gauges. All normal. Attempted to re-start. All necessary electrical functions working except starter neither turned nor engaged. Turned vehicle off. Had dinner. Came back 1 hour later. Turned engine on. Engaged starter. Engine started, Ran smooth and normal. My thoughts: "Partially clogged fuel filter", erratic fuel pump.
"Heat of engine and Arizona 105 o temp. caused starter to malfunction. When cooled down, was able to work. All suggestions will be appreciated.

 

wow 105. sounds like El Paso and my AC is acting skittish.

Alright the rough idle and stuff could be a... well I could hang up a dart board with malfunctions and throw darts and each of them could be a possibilty for the rough start especially ones that come and go.

Also with that hot weather during the restated attempt the first tiem after driving, what was yout temperature guage doing? Believei t or not these old W126s/C126s had a "mechanical" safe mode. If you overheat while driving you will loose power and be at a crawl. Soemtimes after a short trip especially ones with lots of stopping and going, the 5.6 tends to run hot anyways by itself and the 105 degrees dont. If you shut the car off immedieately, you stop all coolant flow etc and for a few secs to a min the temp actually continue to rise. If it goes a bit above normal just enough to kick into safe mode it wont start till it cool off. You'll get all lights, even the fuel pump "buzz" but it wont turn.

Have you had any other problems with it lately?

 

Yah, sounds like it was hot, dieseling can occur due to the fact it uses mechanical fuel injection and can still distribute fuel to the cylinders even with the key off and it wants to run on due to internal cylinder temperatures. Thermostat? Clogged radiator?