[grivera]

Originally Posted by PontiacHO

What temperature does your engine typically run? Could be fuel percolating in the fuel lines. Try one of these one way valves placed at the fuel pump inlet hose. https://www.amazon.com/Engraved-Dire...43209887&psc=1

The engine runs at 180 exactly, which is the thermostat rating. It hasn’t been driven on road, just idle time.

Originally Posted by Schurkey

A fuel pump cannot function without exactly the same kind of check valve(s) as has been suggested.

Remove the fuel pump inlet hose, connect a vacuum pump to the fuel pump. Find out if the check valve leaks, and if so, how much/how bad is it?

Would be worthwhile to determine if the intake manifold is being over-heated by an exhaust restriction on one side leading to too-much exhaust blowing across the intake manifold exhaust crossover. A seized-shut (or partially-shut) heat riser (EFE) valve, for example, or the inner wall of a double-wall exhaust pipe having collapsed. Crimped exhaust tubes, etc.

This engine has RA manifolds and the correct intake gasket for a 1972 intake on a 1969 engine. When I rebuilt the fuel pump using a Then and Now Automotive kit, I performed the blowing and suction test on the diaphragms and they operated as designed. Won’t hurt to check again now that the fuel pump is on a running engine.

I have considered an in-line electric pusher pump to prime the fuel line but wanted to check here first for any testing I may have overlooked.