WOT does indeed delay upshift, it just takes forever to get there. In such cases, the shift is rather harsh. The tank strainer is possible but unlikely, I think, because something that limited the fuel flow would cause stumbling. I test-drove an '87 300TD that had such a problem (due to a clogged fuel filter, said the owner).

Nonetheless, for CYA purposes, I'll pull the jumper hose at the tank-to-pipe junction and see what happens.



OK, I jacked up one side of the car and crawled under. It's much harder to access the fuel hose connections on the 124 body than the 123: the point at which the rubber hose from the tank attaches to the metal fuel line is up over the differential; I could feel the junction and the clamp on the hose but I couldn't see it. On a hoist, not too bad, but I don't have one. I think I'd rather leave it to the mechanic.

As an alternative, I decided to disconnect the fuel line at the primary filter. With the fuel tank nearly full, the level of the fuel in the tank is quite a bit higher than the exit in the engine compartment so there should be a fair 'head' at that point. Do you agree?

In fact, what I got was a trickle (that's a technical term, folks ) of biodiesel: not what I was expecting. Compare the size of the trickle to the end of the primary fuel filter and hose. So maybe there's is indeed a clog somewhere in the strainer or the lines.

The fuel itself was clean -- that's commercial biodiesel from the Midwest in the pint Mason jar. I didn't time it but it was rather slow, not the flow I was expecting. And yes, I removed the fuel filler cap, just in case there's a plugged vent somewhere (or no vent?).

Jeremy

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__________________

"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .343,000 miles Wife's car
2005 E320 CDI . . 148,000 miles My car
Santa Rosa population 177,300 (2026 projected)
Total. . . . . . . . . . . . 668,300
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970