can some one please tell me how can i change the shot off valve at the back of the injection pump on my 81 SD ? at 1st it will take a few seconds to shut off then it kept going for a while longer now i have to use the stop lever on the IP. i measured the vaccume it is 20 HG connceted direct to the shut off valve from the vacuume pump with same results. and found out the diaphragm is torn or leaking inside the valve.
help greatly appreciated
thanks
bob

on this site on shut off valve. There is plenty of information on it and I'm pretty sure a couple/few pictures.

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Jim