I believe i need to replace my shut off valve. although i dont want to buy the part if i dont need to. am i able to tell if the one im using is broke/needs replacing or if im fine?

I had replaced my fuel filters and after when i went to fire up the car it only cranked. after doing extensive research and testing im assuming the shut off valve shut off the fuel line. Am i able to recock or not? i drive a 83 240d.

 

Thanks, but im retarded when it comes to under the hood. i have two questions

1. the brown line thats going from the main filter to the injection pumps. thats the line i check?

2. should i have the engine running?