No crank sensor on a 380.

This doesn't sound like a spark issue to me. How did you test for it?

Can you verify that the fuel pump is running in the no-start situation? Have someone crank, and put your hand on the pump and see if it vibrates. If it doesn't investigate the fuel pump and the fuel pump relay.

Given the odd timing, stops after 5 minutes, I would suspect:

- Engine warms up OK in open loop. At 81 degrees, it goes into closed loop, thinks the engine is rich when it's really not, tries to lean it and kills the engine.

- You have crud in the fuel strainer in the tank. Runs OK until it runs out of gas, then has to sit long enough for gas to dribble down to the pump.

__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe