Welcome, and thanks for using Just Answer. I am Cam, and I will do my best to assist you. When you are finished please click on accept only if you are satisfied. I don't get paid unless you do.Please do not accept if you cannot leave positive feedback. I don't know if you are a tech or a just working on your own vehicle so we may have to fine tune the answer. I only know as much about your problem as you have told me in your post, so my answers will be based on what you tell me so please add all the details you can. About your vehicle,
Does the heater come as part of the whole assembly with the plunger on the top?
Yes, but were you sold the housing then or just the heater?
Remove the fuel filter assembly from the vehicle.
Ground Wire Screw
Fuel Heater Screw
Hand tighten the fuel heater screw until snug.
Fuel Heater Spring and Seals
Take note of original spring and seal positions.
Yes, you would be best to take it out and do the replacement on the bench. Take the two 12mm bolts out, unhool the hoses and wires then set it on a work surface.