if i run a mechanical fuel pump, do i need to change anything on the tank/lines?

 

Depends on what you are working with. Need more info.

 

91 firebird ive got a carb. 350. cut the fuel lines when i took the
v6 out, havent touched the sending unit, i just have a mechanical pump now.

 

Does it run?

The 91 was FI, therefore there is a fuel pump in the tank. Two options. Run the electric in the tank with a regulator, or look at the sticky about how to convert your pickup. It's titled carb gas tank pickup, even has a couple photos. Personally I would retain the electric pump and use a regulator, may not be cheaper, but waaay less work. That would eliminate the need for a mechanical pump.

 

thanks for the help, so just stick with the electric pump, just run a regulator. another ?, there are two lines, any idea what one is return, or visa versa? thanks for the info.

 

Are the lines the same size? If not, and this is only a guess, but the smaller line should be the return. There some other posts about the type of regulator to run, because it also should utilize a by-pass to route exess fuel back to the tank to extend pump life. good luck.

 

Maybe you could energize the pump and see which line the fuel comes out of? Be careful it will be a good amount!

 

what if i got an external electronic fuel pump with regulator, would i still have to touch the one in the tank?

 

Yes, you would have to remove the in-tank electric if it isn't powered.