I will be FINALLY building a bioD still in the next week. Can anyone tell me what seals, rings, lines... in my 1986 F350 6.9IDI fuel system will need to be upgraded? I greatly appreciate the wealth of info in here.

 

I have an '86 6.9 turbo also which likes Bio. You don't have to change anything just get ready to. Make sure you have a spare fuel filter in the truck. Probably the first thing to change are the return line O-rings. It is recommended to go to Viton. Mcmaster carr has them they are part number 9464k24 and cost $6.31 per 50. You can do the return lines at the same time if they seem brittle. I haven't done mine yet.I can't remember if they are 3/16 or 1/4" you can find viton tubing also @ mcmaster carr.If you are handy it is real easy. first open all the injector lines and gently pull up on the return line caps one at a time give a little twist and wiggle no need to separtae the return lines unless you're changing them then carefully compress the o rings to one side with one hand and pull them off bottom one first. some toothpicks can help here. don't scratch the o-ring grooves with a screwdriver. grease up a new set -16- put them on top one first clean and lightly grease the caps put em back tighten the injector comp fittings. and run it. You can blleed the lines one at a time or put the pedal down and blow the air thru