Fuel Pressure Regulators....every thing you wanted to know..

[Legacy777]

I've found that for the most part there seems to be a mis-understand about how or what the fpr's do. So here's a little run down on things.

A stock unit's original design is to limit the amount of pressure going to the injectors at idle. Vacuum pulls open a diaphragm that allows more fuel to bypass back to the tank.....thus limiting fuel pressure.

I'm assuming this is done because the injectors are designed to operate and flow at a certain pressure....and at idle you really don't need the higher pressures.

I guess if you have different injectors you can get an adjustable one to tweak things.......but other then that it's not necessary.....the only thing I can see happening if you raise your fuel pressures at idle is premature wear on seals and/or improper a/f mixture at idle.

Next type you see is the rising rate fpr's. I typically look at these as band-aid fixes. They bump up stock fuel pressures. They're usually found on add-on turbo kits where the stock fuel pressure is not enough.

As I mentioned this is sorta a band-aid fix because you're not fixing the problem at the source, the pump. The proper fix would be to get a larger volume pump.

BTW....there is a difference between higher volume and higher pressure. You can have a higher volume pump with lower pressures and keep a big boost monster happy. This is, IMO the proper way to go. You get a larger volume pump, sized to match your injectors, or slightly larger then what the capacity of your injectors for future upgrades.

THEN.....you do need an aftermarket fpr. The reason is that the stock fpr can not flow the amount of fuel needed back to the tank to maintain the stock fuel pressure at idle. So you need an adjustable high flow aftermarket unit. You put it in and tweak it until you get your stock fuel pressure at idle about where it should be.

Weapon-R actually makes a very nice unit.....I stumbled across it the other day while searching for something. Looks like a high quality unit.

I'm pretty sure I got everything correct here. If anyone has anything different....please correct me.....or feel free to add.

[boostjunkie]

Sounds about right to me.

[eastbaysubaru]

Wow. Thanks for the much needed info Josh. Very helpful.

-Brian

[-K-]

You can get more out of the injectors at a higher pressure. Flow rate on injectors are for a set psi. If you don't have enough fuel pump the pressure will drop under high load. Isn't the pressure because of pushing volume through a small pipe. More volume through the same pipe would make more pressure(but it gets released by the FPR) . And if you can keep the right pressure the pump is putting out enough volume, if it didn't the pressure would drop. It is a band-aid but not for the pump but for not getting bigger injectors, or running more boost.

[Legacy777]

Yes you need a certain pressure to keep things happy, but too much pressure isn't necessarily good.....I guess it's better then not enough and running lean and engine going kaput......but with the right pump, properly adjust fpr, and injectors, everything should work together just fine to give you not so high pressure & volume at idle to flood the injectors into giving more fuel out then they're supposed to......but get good pressure at higher rpms to keep fuel supplied to the injectors.

[JasonGrahn]

Screw that weapon*Rice unit, it's built for scrap heap wanna-bes. Here's the motherload: http://216.242.145.16/products/product.phtml?p=10 or even betta: http://216.242.145.16/products/product.phtml?p=11

BAM! You want fuel regulation, this is all you'll ever need. Use this Y block: http://216.242.145.16/products/product.phtml?p=37 and run a fuel line for each bank of cylinders individually! The next step after that would be to run a line to each cylinder, but i don't think anyone on this board needs that quite yet..