I'm installing a new gas tank, the old one was too small. The old one had a return line from the mechanical fuel pump but the new tank has no provision for a return. Is it o.k to just put a plug in the return line fitting and run just the supply line? I am running a Holley 4bbl. and mechanical pump. Vapor lock doesn't seem to be a problem. Any advice is appreciated. Thanks, Tom
double dat. check your fuel pressure. I run a tri-power set up, and to increase the fuel pressure. I pinched down on the return line. You didn't say what type of engine your runnin. earlier stuff I don't think have return lines. While the later stuff will.
You don't need it with a mechanical pump. Mechanical pumps supply fuel based on RPM, and so long as you're not running a big hipo mechanical pump, you're fine without a return. Edit: Keep in mind that the pump doesn't create pressure, resistance to flow does. As derpr stated, decreasing the size of your fuel lines will often increase pressure, but it can also decrease flow volume. Both are important in your fuel system. You can have adequate pressure, but not flow enough fuel. You can have adequate flow, but not enough pressure. both will lead to fuel starvation issues. Standard rule of thumb for street setups is 3/8" fuel line, and 1/4" return, if you run one. Mechanical pumps are designed to provide a certain pressure through a certain size fuel line (again, usually 3/8"), but knowing your fuel pressure is also important, especially as a gauge of pump health and possible blockages in the fuel system. You can tell a lot of things by reading the pressures inside your engine.
Thanks for the helpful answers. I forgot to mention that I am running 3/8" line and the engine is a 305 Chevy. Maybe I'll plug the return and see how it works. Tom
a 305 would be a later smog model engine. you could get a fuel pump off an late 60's early 70's 327 or 350 and it will not have a return line.
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