A few days ago, my '86 240 died just after I had started it. There was a buzz under the dashboard. It sounded like it was coming from behind the console. It stopped when I turned the key off, but started up when I turned the key back on. The engine would turn over, but not start. Later that evening I tried it again, it started, and it's run fine ever since. I don't really think the sound was coming from the fuel relay; but I don't know of anything else under the dash that would incapacitate the engine like that. The next evening I took the relay apart; and found a cracked solder joint. I re-soldered every joint on the board, and ordered a spare relay just to be safe.

Has anyone had a similar problem? Are there other things I should check? I'm going to drive this thing to Ohio in a week, and I would like to hear your advice.

 

I know in my '90 740, the buzzing is coming from my secondary fuel pump that's mounted on the undercarriage -in the area under the driver's seat. The motor kicks on when I turn the key. Sit in the driver's seat with your door open. Put your key in, and lean out and put your ear as low to the ground as you can then turn the key to position II. You should hear the pump motor start buzzing.

I'm not sure about your car dying, but I'm hoping this might shed some light on the first half of your problem.

 

That's the main fuel pump. The in-tank pump is the secondary one.

 

Right - What he said