ok, The Schrader valver on the test port comes out. Why? because it works like the one in your tire. As long as there is pressure behind it it seals to keep the fuel in. Just like your tires valves seal to keep the air in.

The Regulator. Well this is kinda hard to explain just by typing it, especially for me. This is going to be some real simple comparisons and by far no where near technical.

When u water the lawn the water just shoots out of the hose right? What happens when you put your thumb over the hose opening? It shoots out with more pressure. Why? You are trying to flow that same ammont that was comming out before but through a smaller opening. This is what the pressure regulator does. Its causes a controlled restriction for increase fuel pressures.

How does it know how much to "restrict"? Your engine likes to breath. It takes in several hundred cubic feet when it really gets going (just...imagine pls). Its basically a crude air pump. This creates vacume in the intake manifold and generaly in the intake system. The hose connected to your FPR comes from this. So more vacume = higher load or your engine is working harder. Be it from you flooring it or from a hill or AC etc. The FPR detects this and gives more fuel.How does it do this? simple It "pulls" and ...say a lever that opens and closes a "gate" or door. What moves it back? a spring. This tension or force on the spring is what you can adjust.

Now for a boosted engine there is an aditional source the Fpr can detect. Thats positive pressure. Think of this as a baloon. When positive pressure gets pumped into it It likes to expand, this "pushes" inside the fpr. Increasing the pressure yet again.

How much it increases depends on the "baloon" thats why the SFMU comes with disks. You get the "ratio" or decide on how "stretchy" or soft you want your baloon to be. Too soft and it will increase the pressure too much. Too hard and it wont be enough.


Now for that eclipse98 dude. Why do you have the fuel filter in the return line?

for one, I would want less restrictions on that line.
Two, I would want my fuel filteres BEFORE It goes to my injectors and subsequently to the engine.

Or did I mis understand your drawings?


If it helps here are some links to simple explanations of a fuel system.

http://auto.howstuffworks.com/framed.htm?parent=fuel-injection.htm&url=http://www.icarumba.com/icarumba/resourcecenter/encyclopedia/icar_resourcecenter_encyclopedia_fuel1.asp#top

http://auto.howstuffworks.com/fuel-injection.htm

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