Y do some people run a return line??? there are pumps you dont need them with

Y do some people run a return line??? there are pumps you dont need them with..
what is the real benifit?

takes the load off the pump , smoother fuel flow , cooler fuel

Fuel pumps that flow big volumes of fuel, typically don't like being deadheaded against a regulator. It also makes it easier to control fuel pressure.

All of the above. I prefer a pump with a return on it, not a return style regulator.

jbozzelle wrote:All of the above. I prefer a pump with a return on it, not a return style regulator.

X2. Dead heading works but it is murder on the regulator. Some of the better pumps flow so much volume at such a high pressure that the regulator will never settle in. Creep turns into too much FP in an instant

Returning SOME fuel from as close to the engine as you can get, with a regulator or not, keeps that fuel at a more constant temperature and away from any percolation which does often occur especially in a closed hood regular type vehicle. (Racing or not, the fuel doesn't know the difference).
A by-pass regulator will also keep the fuel pressure from climbing in a dead head situation.

We had a situation using a very good mechanical pump (SBF factory location) at the end of the run causing an over-rich condition to the point of stalling the engine. If memory serves me correctly, this problem was present at 6 PSI. We looked into return regulators and such to solve the problem until we found we could operate the engine at 4.5 PSI to 5 PSI just fine! One wouldn't think a pound or so of fuel pressure would make that much difference, but it sure helped with our situation, fuel pressure rising after demand.

As to high pressure applications, whether mechanical or electric, factories are using return lines for some reason, maybe as have been mentioned!

Dave.