QuestionI've been restoring a 71 250 and no matter what I do I cant seem to stop a hesitation that almost stalls the car when I step on the gas from a stop. New accelerator pumps, timing is correct, changed over to an electric fuel pump (was doing it before I changed the fuel pump), vac lines have no leaks and are all correctly run.
AnswerGary, this question is really outside my area of expertise, but I can give you a couple of suggestions. First, isn't this a Bosch K-JetTronic mechanical fuel injection car? As I recall, these systems tend to be very sensitive to fuel pressure - if the pressure is too high the hesitation you feel may be instantaneously too rich an air fuel mixture, if the pressure is too low, it could be a momentary fuel starvation. Check the pressure regulator to ensure correct operation, and also check to make sure that your electric pump provides sufficient pressure, but not too high a pressure.
Beyond that, another possibility is play in the timing chain. If there is excessive play in the timing chain, it will take the engine a moment to respond to acceleration. I don't know how to check that on your car, but it's another possibility.
Not being overly familiar withhe Benz, that's about all I can come up with. Good Luck!!
Regards,
Dick.
