Fuel Systems

Most fuel system problems trace back to one of two decisions made too early: the wrong pump or the wrong regulator. Electric vs mechanical isn't a style choice — it's an application decision. A mechanical pump belongs on a stock or mildly modified engine where the factory cam drives it at the right GPH for the carburetor; an electric pump belongs on any build running more than about 400 HP, a hot cam that limits mechanical pump stroke, or an EFI conversion. For carbureted applications, you're looking for 6–7 PSI and 100+ GPH from an electric pump — the Holley Blue (110 GPH at 7 PSI) has been the default answer for decades because it hits both numbers reliably. Regulator type determines everything downstream: a carb regulator (0–15 PSI) is a restriction valve that caps pressure before the float bowl; an EFI regulator (30–70 PSI) is a return-style device that maintains rail pressure by bleeding excess fuel back to the tank, which is why EFI needs a return line and a carb setup doesn't. AN line sizing follows the flow requirement: AN-6 (3/8" ID) handles carbureted feeds and EFI returns on builds up to about 400 HP; step up to AN-8 on anything above that. Return-style systems matter on hot builds because a dead-head system (no return) traps heat in the fuel rail during hot soak, which causes vapor lock at restart — the same condition that makes a carbureted car hard to start after a 20-minute stop at a gas station. A fuel cell changes the math on capacity, vapor management, and weight distribution: a 15-gallon aluminum cell in the trunk replaces a corroded stock tank, adds AN fittings in the right locations, and moves weight rearward — which is the right direction on anything that runs a quarter mile. Float level sensitivity to pump pressure is the last piece: a Holley with the float set for 6 PSI will flood on 9 PSI and run lean on 4 PSI, which is why a regulator isn't optional when running an electric pump.