Ok here's the deal. Calling on the brain bank to help with any fresh ideas on this nagging problem. Probably one of the most perplexing problems that I've had to deal with.

I had posted a thread asking for help a while back but didn't generate many ideas. So, I'm gonna try again to explain what's happening and what I've done so far in attempt to correct the problem.

The Problem: the title says it. Cold starts fine, idles fine, accelerates fine, top speed is fine, no smoke, nothing but a hesitation after taking a left turn at speed then some "chugging" for about 20 seconds afterwards.

Left turn and only a left not a right turn.

I've done about everything that I know how to do to diagnose and/or correct any possible fuel restriction and/or air leaks.

Tank strainer clean, new hoses and clamps, two new filters, newer bolt with fresher o rngs on spin on filter, newer good lift pump, Cleared tank vent, visualy checked everywhere for leaks.

Bonus diagnostic tip: been runnin straight D in the 2 tank. When I switch over to the 2 tank all symptoms are GONE. In fact, feels like it rips harder with the new lift pump. So, have to assume that any part of the system that is common flow is good. Would include: the lift pump,IP, fuel pressure relief valve.

Any ideas anybody? Feel free to chime in. Any other diagnostic techniques?

I'm thinking about maybe pressurizing the fuel system with air to look fo leaks. Don't really have any ideas on how to find a flow restriction.

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Current fleet
2006 E320 CDI
1992 300D - 5speed manual swapped

former members
1984 300D "Blues Mobile"

1978 300CD "El Toro"