Quote:
Originally Posted by sunman
The return line is at the bottom to prevent aeration of the gas. EFI 101.
The flush cap EFI fuel cell I’m putting in the trunk has pump, emissions connection and bottom of tank return built in.
Gas in the return line increases pressure, no don’t think so…and there’s a vacuum line vent to the throttle body.
I had my harness redone stand-alone by Dr K and am using everything hooked to it. Not the EGR pump tho
This is an 86 Mustang GT California motor with all emissions parts and no miles. I’d sell it, some dude in Cali lookin for this
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The bottom of the tank return line positioning will richen your AFR and it will not be linear across the engine's operating range. Additionally, the AFR change will vary as the fuel level in the tank goes up or down.
I run a three pump fuel system with between 750 and 1350 lph delivery capabilities. If the fuel is aerated it produces no adverse fueling considerations that need to be attended to. My pumps and all OEM manufacturers pumps draw from the bottom of the tank not the top.
The gas in the return line is not what creates the back pressure for the return line. It is the fact the return line fuel is entering at the bottom of the tank and has to push against the weight of fuel already in the tank. Same as ocean diving. The deeper you go the higher the pressure from all the sea water above you. In the gas tank it it no different.
Most significantly, it will change your commanded AFR, and the change will vary by the amount of fuel in the tank at the time.
Ask me how I know
— been there done that ...