Why do fuel tanks have a return line?
In fuel systems with a return line, the fuel pump is continuously pumping gas through the fuel system at a much higher rate than is actually needed. This keeps gasoline in the fuel lines cool and flushes out any vapor bubbles that might form. This prevents vapor lock in your fuel system.
Is a fuel return line necessary?
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.
How does fuel return to the tank?
Fuel travels along the fuel lines and is delivered to the fuel injectors. Fuel Injector pressures are controlled via a pressure regulator. Any fuel which is not used and exceeds pressure rates is returned via fuel lines back into the fuel tank.
Can you block off fuel return line?
Any fuel going through the return line is simply fuel your engine did not need/could not use. Blocking or restricting the line only increases fuel pressure at the injectors. Blocking the line results in the fuel pressure just being the maximum the pump can push.
How do I calculate fuel line size?
If your pump does not list line sizes, use the table below as a basic guideline….Recommended Size, Based on Horsepower.
| Recommended Fuel Line Size (from the tank to the pump) | ||
|---|---|---|
| Engine Output | Size (inches) | Size (AN) |
| 350 hp or less | 5/16 in. | -5 |
| 350-450 hp | 3/8 in. | -6 |
| 450-650 hp | 1/2 in. | -8 |
Does a carb need a return line?
You don’t really “need” a return; but the car will work better if it has one, on the street. The fuel pump pressurizes fuel to send it to the carb. If the engine isn’t using much fuel (sitting still idling for example) the fuel in the line will be mostly just sitting there, getting hot.
Do you need a return line for a fuel tank?
The aluminum Fuel Tank Return Fitting provides a threaded hole in the fuel tank without having to reach inside the tank. If you are planning on running fuel injection, you will need a return line to the tank. This kit allows you to add the threaded bung with out having to do any welding.
Why do I need a return line in my EFI?
EFI systems require a return line to move unneeded fuel from the fuel injection system back to the fuel tank. This process of cycling fuel from the tank to the injectors or throttle body and back to the tank is a complex process.
How much does a fuel tank return line Bung kit cost?
Fuel Tank Return Line Bung Kit, Universal Part #: 40004-9 40004-9 Weight: 1.00 lbs 1.00 lbs Our price: $25.00 $25.00 Buy in monthly payments with Affirm on o
How does a returnless fuel pump system work?
Returnless systems use an FPDM (Fuel Pump Driver Module) which is an electrical device designed to keep the desired pressure at the injectors and controls the power sent to the fuel pump(s). Unlike a return fuel system, the fuel pump is controlled by an FPDM and is not constantly operating at 100%.