If one has a FD that is not gunked up that badly, could one remove the EHA, shoot carb cleaner in both chambers, and move the air flow diaphram repeatedly to allow the cleaner to penetrate the plunger cavity? This is with the hope that a sticking plunger on the FD is the root cause; mine is only blowing black smoke out the exhaust. I was searching for evidence of successful attempts of that effort when I found this post.

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1988 300E
1993 300SL
1994 540i

If I have a problem with my Mercedes, I go to MercedesShop. If I have a problem with my BMW, I go to BimmerNut.
If I have a probem with my Dell, I reboot it. I was an engineer for them for 10 years and we blamed everything on Microsoft.