GM 4 tube sending unit, what tubes do what?
Posted: Sun Jan 16, 2011 1:38 pm
I have a GM TBI sending unit I plan to use in my '81 Elky EFI conversion. It has 4 tubes in it. I understand that the 3/8" one that hooks to the pump is the output. There is a 5/16 line that goes all the way down by the bottom of the tank, then there is a 5/16 that terminates near the top of the tank that seems to have some kind of check valve on it, and then there is another 3/8 tube that just stops near the top of the tank.
Anyone know which tube does what? I am guessing the 5/16 that goes to the bottom of the tank is the return line, the 5/16 with the check valve is for the carbon cannister, and maybe the 3/8 that stops at the top of the tank is for a vent to the filler neck. Does that sound right?
Thanks,
Clay
Anyone know which tube does what? I am guessing the 5/16 that goes to the bottom of the tank is the return line, the 5/16 with the check valve is for the carbon cannister, and maybe the 3/8 that stops at the top of the tank is for a vent to the filler neck. Does that sound right?
Thanks,
Clay