Quote:
Originally Posted by fast4d
most newer EFI systems run 'returnless'. there's no circulation of fuel
I would think the returnless pumps are cycled and don't run constantly on the same intensity therefore eliminating overheat conditions.
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Returnless simply means that the regulator is at or in the pump assembly. These systems will run a set pressure and modulate the IDC to account for changes in manifold pressure. I've never seen a pump that cycles (although many autos use voltage modulation to the pump to keep it quiet at low load and prevent regulator overrun at low IDC)
edit to add: There are also semi-returnless designs (such as BMW auto) where the fixed pressure regulator is contained in the external fuel filter with output to the engine and return from filter to tank.