[Gmecm] TBI Fuel problem

[Craig Smith]

Everyone

I'm having a fuel pressure problem with a conversion we're performing on my fathers MGB.  The fuel system is plumbed just as a stock Chevy TBI system running at 16# With an external Carter fuel pump mounted in the right hand battery box about three feet from the tank.  The fuel return from the tbi is plumbed back to the tank dumping about an inch from the tank bottom. 

After running for about 5 miles I'm loosing fuel pressure.  It acts like a vapor lock condition.  After it sits a few minutes it cranks and runs fine until it heats back up.  I figure I'm picking up heat from the engine compartment.  Has anyone placed an aftermarket fuel return regulator downstream of the pump returning to the tank and blocked the return at the TBI?  Is the fuel return thru the TBI used to cool the injectors, or does it have another purpose? 

Thanks
Craig