Replace the 12" long section of rubber fuel hose that connects the hard fuel line from the tank, to the plastic pre-filter. I know this from experience....I would bet that in many of our 20-year-old-plus cars, this hose is original! It will develop cracks on the inside diameter that may not be visible from the exterior...when you connect it to the fuel line and pre-filter and sinch down tight with a band clamp, the cracks distort and allow air in. On my car, this was the cause of many days of poor running, and ultimately a no-start condition. When the hose just starts to leak air, you will be able to drive the car fine, but you will notice hesitation and lack of power when you accelerate. Eventually, as the air leak gets worse,a big air bubble will form in the IP preventing starting.

Another thing, when the car is not running, you will not see fuel leaking here because there is no pressure head.....(on my 300TD, the fuel tank sits very low, and this hose connection is above the tank. On sedans, the tank sits up higher, so I would suspect that you might see fuel leaking here when tank is full).

Anyway, replace that hose and you might solve the problem.

Good luck,

Mark

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1984 300TD Wagon, 407,800 mi (current daily driver)
1985 300DT Sedan, 330,000 mi (gone to that great autobahn in the sky)