The crankshaft position sensor may fail. Symptoms of this are: The engine will crank—but not start—especially when the engine is warm. The car may start again if it is left to cool off, but it may run roughly or have poor performance. Communicating these specific symptoms to your technician can save diagnostic time.Google+
Car Problem Reports
Mercedes-Benz G500 Engine Performance Problems Due to Crankshaft Position Sensor Failure
Mercedes-Benz G500 Problem
Visitor, 2003 Mercedes-Benz G500, 100,000 mi
Car was performing fine and suddenly power was cut off and car stalled, dash lights all came on. Starter would try to turn engine over but key was not springing back since engine did not engage, left alone the starter would burn out so I turned it off after about 2 seconds. About 20-30 mins later, car has cooled off a bit and was able to start and get back on the road only to experience the same problem about 5 miles later. Same procedure again and same results. The third time, I had the car towed to avoid any unnecessary damage to engine.