So I replace the wire harness last week all was good in the universe!!!!!!!!!!! Then I go to get my Sunday moring coffee and that DAMN thing won't start AGAIN!!!!!!!!!!!! Its not cold out this time so the only common thing from the other time is the car sat for more then 24 hours cranks fine just won't catch!!!!!!!!!!!!!!!

I didn't follow the last thread, but have you checked fuel pressures yet?

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2016 Monsoon Gray Audi Allroad - 21k
2008 Black Mercedes E350 4Matic Sport - 131k
2014 Jeep Wranger Unlimited Sahara - 62k
2003 Gray Mercedes ML350 - 122k

No not yet, thats what I was thinking today I think thats my next move. Any Idea what I should have for fuel pressure???

Somewhere in the mid 50 psi range, last time I checked I think mine was 55 psi.

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98 Dodge-Cummins pickup (123k)
13 GLK250 (135k)
06 E320CDI (323K)
16 C300 (62K)
82 300GD Gelaendewagen (54K)

Figure out what you aren't getting. Fuel or spark. Then check for error codes.

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Current cars:
2000 ML55 AMG, 174k miles
2003 C240 T-Modell, 202k miles
1995 S320, 207k Miles

Anyone know where I can pick up fuel pressure test gauge, auto parts store??

As it has in the past went out today car started right up!! WTF this thing is driving me crazy

Think back and determine if the weather was damp when it would not start, and dry when it would. If so look to the plug wires and spark distribution for leaks that allow humidity into the sytem.

Any know why the parts for the 400E are so much $$$$$$$ $75 for cap $40 for a rotor $200 for wires DAMNNNNNNNNNN I might need to start selling crack on the side to do a half of a tune up!!!!!!!

Today I did the fuel filter, pump relay, and fuel pressure regulator still take 4-5 seconds to start. Let see if these changes help!!