Mechanical fuel pump on 86 samurai was only putting out 2psi causing truck to stall. Upon removal of the pump I discovered fuel pump rod has no resistance. my other samurai the fuel pump push rod in the cylnder head would want to slowly push itself out of the head when i installed it. This push rod stays whereever i put it. If the cam is worn would that cause this? Im hesitant to put my new mechanical fuel pump. Only thing i can think is to hand crank engine at crank to see if it pushes the rod out? Any ideas would be awesome, thanks.