I carbed my '88 firebird about a year ago and went through the trouble of doing it right with a diaphragm regulator and all that other jazz. Now because I know the factory pumps aren't exactly known for their longevity, I want to examine my options for replacement.

I've read in a thread here on TGO that somebody actually rigged up a mechanical pump and ran it through his factory return line. How feasible is this? Will this still pull fuel until the tank is empty? Will I need a vented cap?

On a sidenote, if this IS in fact a possibility (I'd like to avoid dropping the tank. That's a buttload of work I could do without) will a L31 out of a '96 suburban come with the proper cam lobe to support a mechanical pump? and if not is it feasible to use an electric fuel pump out of the return line?

Thanks for your input.

 

Fuel pump lobes started disappearing from factory installed cams in the early 90s. So, no, I doubt the cam in that Vortec motor would have a fuel pump lobe.

Also, you can't just bolt on a mechanical pump and draw through a non-functional factory in-tank (too much restriction). Never paid that much attention to the return line but I seriously dobt it goes all the way to the bottom of the tank like the pickup side does.

 

A factory L31 block likely isn't machined for the mechanical pump. Some may have been, but I've never seen one that was.

 

From the L31 blocks i have used in my cars, the 96-97 blocks had provisions for a mechanical fuel pump push rod... the 98+ blocks do not have a hole drilled for the push rod. All have a mounting boss.