1979 350 SL fuel prime

[willsandbills]

Looking for help with a problem thats driving me silly. My car is a 1979 350 sl with CIS k jetronic ie mechanical injection and no ECU.

The question is this, is the fuel pump supposed to run for 1.5 to 2 seconds when the key is turned to its first setting ie IGN?? most cars i have seen do but i have no exact car to match it to.

if the answer is yes, how does the fuel pump relay get turned on for that short period.

all help appreciated

 

[mct_cars]

I think the noise you hear is the fuel pump being primed. Our old '67 MGB did the same. It's still running, just doesn't make a noise once pressurised.