I had my 1990 420SEL running great. Yesterday I was flooring it from a traffic light and as it was accelerating, it just shut off. I have idea why. It was driving perfectly and then all the lights came on the dash board and there was no power. i pulled to the side of the road and tried cranking it and all it did was crank (sounded different too than the usual cranking sound). I towed it home and started looking at it. It has spark. I tried spraying ether in the the plunger area and still nothing. I pulled the relay and jumped positions 7 and 8 and tried starting it and still nothing. It just cranks. I'm open to ideas of what to check next.

In the past 2 months I've replaced-

both fuel pumps

fuel filer

fuel accumulator

fuel pressure regular

cold start injector

cap/rotor/spark plugs and wires

new 02 sensor

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Current fleet-
2015 BMW 750i xDrive
2009 BMW 535i xDrive
2004 Chevy Avalanche 4x4
1993 Mercedes 300SD
1993 Mercedes 300SE (parts car)

Previous Benz's-
2001 Mercedes SL500
1983 Mercedes 300SD
1980 Mercedes 300TD
1996 Mercedes E300D
1999 E300DT
1984 300TD-T
1988 Mercedes 560SEL (parts car)
1979 300SD
2003 E500
2004 S430 4Matic
2001 E55
2003 E430