Engine cuts out at high speed only
 

Car: 1986 300E

Day 1 - Driving down the highway at 60-70 mph, engine suddenly cuts out. I pull over to the side and start the car. Car starts and all is fine.

Day 2 - Same thing, drving on hwy at 60-70 mph. Engine cuts out. The engine is being driven by the transmission now - I didn't switch the trans to neutral. Without thinking, all I do is turn the ignition off and turn it back on (did not crank the starter) and the engine fires right up and no problems.

Day 3 - Same thing. But this time, I pulled over again and tried to start the car. After about four of five tries, the engine came to life and it ran like a champ.

Temperature on all three days was about 50 degrees. The stalling happened after drving about 12 miles from work out of which 7 are on the highway usually driving close to 68mph

What could be the problem? Is is fuel delivery related - vapor lock, or clogged fuel filter, or bad fuel pump/fuel pump relay.

Thanks

Fuel delivery OR lack of it is a common problem.

ON the return side of the system you need to have a quart of fuel in 25-30 seconds.

Is it not a very dangerous thing to turn off the ignition while the car is running? the steering wheel can be blocked.

MB steering columns don't lock until the key is removed.

Any insight on where to start troubleshooting the problem will be greatly appreciated.

Would replacing the fuel filter be a good start or is the problem more serious.

Thank you,

HS

i would go straight to the distributor cap and rotor.look carefully at the centre carbon pole in cap where touches the centre of rotor.other possibility is tdc pickup at the flywheel going to ignition unit.

Check the OVPR fuse and all fuses in the box...they corrode where they touch the copper fingers.

Does the Tach' drop to zero when it does this while still rolling. If so, the coil is suspect.


.

I experienced this in the past--FUEL PUMP RELAY!. I think it was around $125 back when I had my 300E. Its located right behind the battery...

Replacing the Fuel Pump Relay fixed the problem. Thanks Agron.