Help! As I'm driving down the highway at 65 miles an hour the machine just turns off I'm totally dead in the water. As I'm coasting at 55 miles an hour I put the car in neutral and turn the ignition but no go. I pull over to the side of the highway and after I come to a complete stop the car starts right up.

I have 200k, It's my daily driver to and from work. 20 miles each way. I've changed the fuel pumps two years ago. I just replaced the fuel relay, got a tune up a couple hundred miles ago. I've also had the oil changed. It seems as if after the service I'm having this shut down problem. Can someone shed some light on this for me?

WHy did you replace the fuel relay? Was it before or after? Someone in another thread was having a similar problem.

My car went out and I was told by my the mechanic that the relays needed to be replaced. I paid the have it replaced.

possibly the relay he replaced it with is defective?

Stanmick63,
I have a '85 500SEC. I've posted a number of times on this subject.
My car would shut down at the oddest times. And it would not re-start.
I finally discovered a bad solder joint on the relay.
I even picked up a replacement and it also had the same bad solder joint.
Just open the relay(s). Check the larger of the two solenoids. The back side of the circuit board. The main support for the coil of wire, that is the solenoid, is also the ground. If you see a dull gray solder joint and maybe a circular crack this is your culprit.
Re-solder the joint, trying not to overheat the circuit.
Mine has not missed a beat since I did this. It took all of 15 min. to fix.
Good luck, John F.