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Fuel line size - 85 635 March build

Posted: Mon Sep 13, 2021 10:13 pm
by Jlc
I plan to replace the fuel lines from the pump to the filter as well as those leading to the filler. It appears to be 8mm and 12mm from realOEM - I assume that is ID. Any tips or other hoses I should get. Do you use regular hose clamps?

Re: Fuel line size - 85 635 March build

Posted: Tue Sep 14, 2021 5:07 am
by hornhospital
Fuel injection pressure rated hose ONLY. 8mm I.D./12mm O.D. is correct. Regular (screw clamp) hose clamps are ok. The ones with the formed thread rather than slotted threads are better for the hose.

Re: Fuel line size - 85 635 March build

Posted: Tue Sep 14, 2021 10:35 am
by Jlc
Thanks. I had mistakenly assumed there were 2 different sizes.

Re: Fuel line size - 85 635 March build

Posted: Tue Sep 14, 2021 1:42 pm
by anchored
I used 5/16 because it was cheap and I am a sinner.

Re: Fuel line size - 85 635 March build

Posted: Tue Sep 14, 2021 4:36 pm
by Ralph in Socal
Jlc wrote:
Tue Sep 14, 2021 10:35 am
Thanks. I had mistakenly assumed there were 2 different sizes.
You’re not mistaken. 8 mm ID FI hose mostly except for the 12 mm ID line from the tank port to the inlet on the external fuel pump. About 2 feet long but varies a small amount based on model year. This line is not under FI pressure so just good quality fuel line is adequate. A bit difficult to replace the line as it snakes between the body and the fuel tank. Loosening the tank mount bolts and allowing the tank to lower a little bit helps a lot

Ralph

Re: Fuel line size - 85 635 March build

Posted: Tue Sep 14, 2021 5:06 pm
by Jlc
Ralph,

Thanks. I plan to replace all the lines back there while I'm at it.

It's maintenance month - new belts, oil, filter, a few cracked lines, CV Boots or possibly entire axle assemblies, pittman arms (dogbones), sway bar linkage. Good news trans fluid is fine. May do radiator hoses while at it and flush..

Re: Fuel line size - 85 635 March build

Posted: Thu Sep 23, 2021 8:10 pm
by Jlc
Ralph, Any idea how much of the High Pressure 8mm line I need?

Thanks,
Jim

Re: Fuel line size - 85 635 March build

Posted: Sat Sep 25, 2021 4:38 pm
by Ralph in Socal
8 mm ID under the hood is about 3 feet. Don’t forget “the little perisher” (ode to Brucey) hose that feeds the Cold Start Valve.

Another 2 feet or so by the fuel pump and filter assembly. The return lines (about the same lengths) are not under FI pressure so good quality fuel lines are fine.

Ralph

Re: Fuel line size - 85 635 March build

Posted: Sat Sep 25, 2021 11:16 pm
by Jlc
Thanks. Under hood looks good but will double check.