View Full Version : return line with GM TBI on 360
09-25-2008, 11:31 AM
I just bought a GM TBI setup with the Affordable FI harness for my 86 GW and am mapping out my project. Does anyone know if I will need to modify the return line to the tank or should I be OK there? I have seen a couple of vague anecdotal references where some people had issues with return lines being too restrictive, but no one doing exactly what I am. Does anyone know for sure? Thanks in advance.
09-25-2008, 11:41 AM
I ran a new supply line (3/8" Steel) down the frame and used the stock 5/16" line as a return line. I use 3/8 rubber on the 5/16 nipple at the tank sending unit and the stock 5/16 rubber on the 1/4" return nipple. It has been working fine for several years and tests good with a pressure gauge.
09-25-2008, 11:44 AM
This is probably a stupid question, but I am sitting in my cube at my office and can't visualize it. Is there anyway to do that without dropping the tank or should I just factor that in as part of the job?
09-25-2008, 12:13 PM
You don't have to drop the tank. Flip the back seat up and peel back the carpet. There is an oval shaped cover held down with 4 rivets. Drill out the rivets (don't go too deep, the fuel tank is under it 2"-3") then pry the cover up. Replace it with sheet metal screws.
09-25-2008, 12:16 PM
Oh sweet... I didn't even consider attacking from above. I really appreciate the input.
09-26-2008, 06:10 AM
I also ran a new 3/8" supply and used the original 5/16" supply as return (using S-10 tank with submerged pump). I have no idea whether this was actually necessary, but it does seem to be sufficient.
I ran all new 3/8" supply and 5/16" return leaving the originals capped off and in place.
This was for a Holley Projection 2D following their spec's.
I also carry a carb, fuel pump, filter and misc hose/clamps, just in case I have to revert to get home.
09-26-2008, 06:39 AM
I ran a new supply line but used the original 1/4" line and replaced the hoses. No issues.
09-26-2008, 08:01 AM
Used the factory line as well with no problems :)
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