Fuel pipes wrong way round

[Darren69]

yea, it think it should still run no matter which way around they are, the fuel pressure regulator is there to prevent any damage due to over pressure and it would still work the same but in reverse.The Low tank level sensor would probably take a day off however. If it actually works that is?

[spuggy]

Originally Posted by Darren69

fuel pressure regulator is there to prevent any damage due to over pressure

Actually, no. What you've described would be an over-pressure relief valve. I don't know of any vehicle that has one of these in the fuel system (although everything has at least one - and some have multiple - in the oiling system).

Before the mid-80's, fuel pumps were "roller cell" type; however, almost all modern fuel pumps are "positive displacement", which cannot develop any pressure without a restriction or control in the circuit. Hence the FPR.

Without one, you get flow, but no pressure - the injectors need a certain pressure range to work correctly. 3 bar (or 45 PSI) is pretty typical for EFI.

Carbs generally want a lot less (like 3 PSI or so) - or you tend to overcome the float needles..

The fuel gets continuously pumped (circulated and returned to the tank) both to avoid localized overheating (eg in a fuel rail over the cylinder head) and because the fuel is used to cool and lubricate the pump.

Interestingly (well, I thought it was anyway), very common in turbo systems to use a rising-rate FPR - the regulator has a vacuum reference, that off-sets regulated fuel pressure by the amount of pressure "seen" in the intake manifold. So when there's 1 bar of boost in the intake manifold, the fuel system is regulated to the nominal 3 bar + 1 bar. Which both proportionally provides extra fuel (assuming the injector duty cycle remains the same duration) and maintains the advantage (pressure differential) of the injector over the intake for a good spray pattern.