BenzWorld Junior Member
Date registered: Aug 2012
Vehicle: 1984 300D, 1990 420SEL
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420SEL - Fuel Distributor Rebuild
I rebuilt my 1990 420SEL fuel distributor last night in an effort to solve a hard start condition. If the car sits for more than fifteen minutes, it would start on the first turn for a moment and then stall. The next attempt to start woudl be successful and a slight "seeking" idle would be experienced until the engine was up to temperature. If the vehicle sat for more than twelve hours.. this symptom would not appear.
Here's what's been replaced or repaired so far:
Distributor cap, spark plugs, wires, IAC (cleaned), all vacuum hoses checked, air filter, fuel filter, EHA valve, checked OVP, and repaired fuel pressure regulator vacuum line. All of these repairs significantly improved this vehicles performance but didn't solve the original symptom.
Next up was the fuel distributor as I could clearly see fuel draining into the throttle body after the engine was off and it was sitting for at least two minutes. Upon further inspection, significant varnish was found in the throttle body with an origin of just under the air meter arm below the fuel distributor.
So off it came and I spent about three hours carefully rebuilding the fuel distributor with a kit I found on ebay by American Machinist.
I'm driving it today and if it still runs well by the time I get home I'll start posting instructions on how to rebuild. Hopefully with my findings and others I've found on this forum, I can add to the knowledge base already available on BenzWorld.
Updates should be around 10:00PM EST or just a little later.