I have adapted three GM S-10 throttle bodies to a flathead Lincoln V-12. We think it looks cool. We're using a FuelTech ECM this is pretty intuitive. Problem is fuel pressure drops from 10 psi to three psi when started. I may have done this to myself with a surge tank and a carburetor style lift pump slightly under the gas tank. Fuel goes into the surge tank on the top, and out the bottom. Also connected to the surge tank bottom is the return line. A vent line to the gas fill pipe is on the top as well. A stock style Carter TBI fuel pump and filter are mounted in the frame rail. We took the springs and the gasket center out of the built in regulators and are using an Aeromotive bypass regulator in return from the TBI bodies. The regulator also has a pressure gauge.

Had to prime the TBI pump to get fuel flow, and then had to use three washers in the regulator spring chamber with the stiffest spring to get 10 psi on the gauge with the engine not running but both pumps on. All lines are 3/8. Wondering is the overflow line to the gas inlet at the gas tank is too low resistance to flow relative to the line through the pump and fuel injector bodies? Engine starts fine, but then the ECM gives a low pressure alarm and the engine dies.

All advise is welcome
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