Quote:
Originally Posted by FrugalNinja250
So your fuel supply is like this:
Tank-->line-->pump-->injector rail-->line-->cooler-->line-->Tee on fuel pump inlet line? So the fuel cycles continually between pump and cooler, with whatever the injectors take removed from the loop volume and replaced with fuel from the tank? I assume there's a checkvalve upstream of the Tee?
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Yes, the fuel does cycle continuously from pump to cooler. But no, it's not put together exactly as you outlined just now. The main difference from what you've described is that my system uses a "dead end" fuel rail like every other OEM motorcycle system on the market. And, of course, the system's fuel pressure regulator acts as a "checkvalve".
It goes:
Step 1. Fuel leaves the fuel tank through the petcock (just "on" and "off"), down a fuel line and into one branch of a three-way Tee. The second branch of the Tee recieves fuel coming back in from the return loop (more on that later) and the third branch of the tee takes that return fuel and new fuel from the tank to the bike's fuel pump. Call this combination "input fuel".
Step 2. The fuel pump (Suzuki LT-R450 Quadracer) pressurizes this input fuel to about 50 psi and sends it down a line into the fuel pressure regulator (also a Suzuki LT-R450 Quadracer part).
Step 2.a. A "bubble line" or you could call it a "vapor-relief" line also leaves the fuel pump. This line is hooked up to what used to be the vacuum port on the bike's petcock. (Side note: when you take out the petcock's vacuum diaphram the vacuum port turns into a useful fuel line).
Step 3. The fuel pressure regulator reduces the line pressure to 42 psi and sends that pressure down the line to the throttlebody fuel rail and into the injectors.
Step 3.a. The remainder of the fuel pump's output volume (that doesn't go to the fuel rail and out through the injectors) is bled off into a return line.
Step 4. This return line fuel is routed through the cut-down Flexalite 4130 fuel cooler that's mounted to the bottom of the K&N 0990 air filter before it continues back to the Tee mentioned in Step 1.
If you've got time on your hands and you believe that "a picture is worth a thousand words" heres a video I made this summer that must be worth about a million words (if you're interested in the subject matter, that is).
Link to original page on YouTube.