[Gmecm] TBI Swap - Iron Duke Tech IV

[Jay Vessels]

Hi there!

> For now though, I am confused about one thing... which is the Fuel System:
> I know I need an electric pump for this setup... but how does the fuel 
> flow?   Do I need to run a new line for fuel return?  (does it just flow 
> past the Throttle Body and back into the tank, and the TB just uses what 
> it needs in the middle?)  Just started thinking about this recently, 
> lol...  Which would mean on a carburated engine the bowl is filled just 
> as quickly as the RPMs are turning the mechanical fuel pump, right? 
> (thus it never overflows)

The fuel system consists of a pump pushing fuel from the tank, through a 
filter, to the TBI which has a built-in fuel pressure regulator, past 
the injectors (which are effectively T'd in the line inside the TBI) and 
through the return line to the tank.  Fuel flow is constant while the 
engine is running -- unused fuel is constantly returned to the tank.

The pump needs to be one for fuel injection -- most carburetor electric 
fuel pumps won't supply enough pressure or volume.  The stock TBI pump 
should produce a (regulated) 9-13 psi as measured between the filter and 
the TBI inlet, and flow at least 1 pint in 15 seconds.  The TBI system 
you've grabbed originally had a pump mounted in the fuel tank, and a 
return line also entered the fuel tank and returned fuel to the bottom 
of the tank.

You will need a return line that goes from the TBI return line fitting 
to the tank.  Make sure the return line empties into the bottom of the 
tank, and not the top -- you don't want to be spraying fuel into the 
open air space above the fuel.

Jay Vessels
1982 Chevrolet S-10 Sport, 2.8V6 TBI
1984 Chevrolet S-10 Blazer Sport, 2.8V6 (TBI pending)