I have replaced the fuel pump several times in the cars. It can be done. An important step is to make sure the fuel pump eccentric is at its low point. This exerts the least amount of pressure on the fuel pump arm. Simply rotate the engine by hand until the fuel pump mates to the bolt with least amount of force. Also make sure engine assembly lube is on the fuel pump arm at the contact point. The bottom bolt should turn on by hand and mostly seat. I can't remember exactly how to get the wrench in place to torque the bolt. I have done it with the cooling tubes in place.
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