Its very simple thing. Depends what ammount you want to spend.
Know your engine Model Number most likely D15, It is installed on fuel rail by two 10mm bolts. Remove it remove the pipe and goto shersha and see same engine (important) get it removed from it, Do not trust shop keeper. "Yehe lag jata ha apke gare ko" statement from them is not going to help you because they all seem to be same but have different pressure ratings for different engines.
Total cost: 500 PKR.
OR Goto Mechanic and spend 1k + for such simple job