Not familiar with your car, but your hypothesis makes sense to me.

If the accelerator pump chambers are dry (no squirt), then you are definitely without gas in the carbs. But it also sounds like your pump loses its prime as well because it should not take more than a few turns to get enough gas to the carbs.

Maybe a small pump on a relay that runs for ten seconds when the key is turned on and then shuts off? A guy on the veterans board had all sorts of trouble with excessive fuel at idle with an electric.

__________________
Chuck Taylor
Falls Church VA
'66 200, '66 230SL, '96 SL500. Sold: '81 380SL, '86 300E, '72 250C, '95 C220, 3 '84 280SL's '90 420SEL, '72 280SE, '73 280C, '78 280SE, '70 280SL, '77 450SL, '85 380SL, '87 560SL, '85 380SL, '72 350SL, '96 S500 Coupe