MY 1989 560 SEL IS VERY DIFFICULT TO START WHEN IS WARM OUTSIDE. IN COLD WEATHER IT STARTS ON THE FIRST TRY BUT WHEN I STOP AND AND TRY TO START THE CAR AFTER IT IS WARMED IT TAKES A FEW CRANKS BEFORE IT STARTS. AT ONE POINT IT JUST REFUSED TO RESTART AND I ENDED UP REPLACING THE FUEL PUMP, FUEL FILTER, ACCUMULATOR, EZL, IGNITION COIL, DISTRIBUTOR CAP, ROTOR, OVP, SPARK PLUGS, ETC, AND IT STARTED AGAIN. STILL HAVING THE SAME ISSUE WITH THE HARD START WHEN HOT....MOST RECENTLY AFTER COMING HOME FROM WORK AND TRYING TO START THE CAR IN THE MORNING IT WILL NOT EVEN CRANK. ALL THE LIGHTS WILL COME ON AND YOU CAN HEAR THE BUZZING SOUND OF THE FUEL PUMPS BUT NO CRANKING I CHECKED THE BATTERY AND CABLES FOR ANY SIGN OF CORROSION BUT EVERYTHING LOOKED FINE. I HIT THE STARTER A FEW TIMES WITH A HAMMER AND STILL NO CRANKING. I GAVE UP AND LEFT THE CAR IN THE DRIVEWAY FROM WEDNESDAY TO SATURDAY AND PUT MY WORKING PANTS ON SUNDAY TO WORK ON IT AND DECIDED TO GIVE IT ONE MORE TRY. TO MY SURPRISE THE CAR STARTED JUST FINE. CAN ANYBODY TELL ME WHAT IS GOING ON?? I AM ABOUT TO GIVE UP ON THIS CLASSIC. I HAVE OWNED THE CAR FOR A LITTLE BIT OVER A YEAR NOW. IT TOOK ME 3 MONTHS AND 2 MECHANICS TO WORK ON THE ABOVE MENTIONED ITEMS...THXS

Not sure about the hot starting problem, but...

Are you sure the shifter was positively in either P or N? Sounds like on Wednesday it might have not been, so the P/N gear interlock switch prevented the starter from cranking. Or maybe your shift linkage needs new bushings and/or adjustment as it is no longer falling exactly in place on each gear position due to bushing wear.

When Mercs have trouble starting hot, one common cause may be related to air bubbles forming in the fuel lines (fuel cavitation I believe its called) because pressure is not maintained due to a faulty fuel accumulator or fuel pump(s). But if you've already replaced both, could be something else in your case. But just to be sure it might be a good idea to check the fuel system pressure with the engine running, and then see for how long a correct reading is maintained after the engine is shut off. I believe the accumulator should be able to keep the system pressurized for up to 30 minutes. It also now comes to mind that perhaps one of the injectors may be leaking fuel into a cylinder, or the cold start valve is leaking fuel into the intake manifold.

Good luck
-Alex

__________________
300E 1986 - 117KMi
Sikkens Metallic Azurite Blue
Member #120 of MB Club VE
Caracas, Venezuela