REV COUNT DROPS TO ZERO WHILE DRIVING

[maloisane]

I own a 500sec MODEL 126.

The car cuts off while on cruzing and a sencond or so later you start it again and it comes back on.Th elocal merc specialists suspected a fuel pump relay and we replaced with a new one and it still cutts off while driving.

Defition of cut off (While the engine is runnign and you drining 100k/h or so the car cuts off)

Please help witha correct diagnosisi and may more specific questions will describe the problem futher and clearer

 

[jberks]

Sounds electrical. I had a car once that developed a hairline crack in the secondary coil. Would run fine, then suddenly cut out, and restart almost immediately (often before the wheels had stopped turning). I'd doubt the fuel pump as I would expect different symptoms. Id be checking the ignition wiring. Do the ignition lights come on immediately the engine stops ? Does it always start ok ? Ho whard is it to restart ?. If its fuel starvation I would expect a second or two delay before it would fire again.
Thinking about it, have you checked the fuel filter and pick up. Perhaps its getting clogged, engine stops so suction is released.

 

[Arnie]

The engine has a variety of fuel cut-off solenoids, including one for over-run. These may be the cause of the problem or otherwise, the problem could be ignition or wiring related. A fuel-pump problem would not be so on/off.