Fuel pressure gauge

[Raymont]

Fuel flows to the rail first, then through the fuel rail to the fuel pressure regulator that is bolted on to the fuel rail, witch is connected to the fuel return line

[88BlueShelbyZ]

ok, ok, back to the point I was getting at. What should my pressure be at the schrader valve with 52lb injectors, afpr, FMI stage II computer & 3bar?

[Raymont]

Do you have your gauge hooked up? Most cars are diffrent, but i know stock fuel pressure (55psi) would be a good place to start. Ive never worked with anything with a afpr, but I'm guessing you adjust accordingly to your set up. For example if its running hog rich lean it out, if its running lean, add some fuel. I don't think you would really need a fp gauge to set it up but it would be helpfull. I know I read somewhere that guys with +20%'s ran 45psi of base pressure. If that helps any.

[89daytonaTII]

Quote:

Originally Posted by 88BlueShelbyZ ok, ok, back to the point I was getting at. What should my pressure be at the schrader valve with 52lb injectors, afpr, FMI stage II computer & 3bar?

what is this "fmi stage II" computer? Whatever it is it better be calibrated for a 3bar map sensor, or the two will not work together.

If the computer is made to work with the +40's and 3bar map then the fuel pressure should be at 55psi static. As the re-cal'd ecu would be controling injector pulse width on those +40's to run at the stock 55psi. After that the AFPR is just for finer tuning of the setup, whether it needs more or less fuel depends on your engine.

[Raymont]

(Drunk right now) I know what 89daytonaTII is saying. The computer is controlling the pulse width of the injectors (how long their open and closed), so even at 55psi of fuel pressure it would run at the correct a/f ratio. For example, lets say you had a stock computer with +40's. The computer would be opening the injectors the same pulse width for stock injectors, witch would be way too long for +40's to be open at idle......causing your car to run way way rich.... so then what people do to compinsate for that is they turn down the fp. Then they use an rising rate regulator to get the fp up to where it has enough fuel to support the elevated boost that you would be running.

[88BlueShelbyZ]

Quote:

Originally Posted by 89daytonaTII what is this "fmi stage II" computer? Whatever it is it better be calibrated for a 3bar map sensor, or the two will not work together. If the computer is made to work with the +40's and 3bar map then the fuel pressure should be at 55psi static. As the re-cal'd ecu would be controling injector pulse width on those +40's to run at the stock 55psi. After that the AFPR is just for finer tuning of the setup, whether it needs more or less fuel depends on your engine.

Sorry, the FMI is Forward Motion Inc. Stage II. And yes, it is calibrated to work with the 52lb injectors and the 3bar map.

[Raymont]

FP really shouldn't be too huge of an issue then, you may have to tweak it just a tad to set it up because each car is diffrent.

[CSXTasy]

If you want to put a gauge in the car, you can. I have a Cyberdyne fuel pressure gauge i'm putting in my GLH. It has a sender you can hook up to the fuel rail and a digital gauge for inside. Just don't let the sender hang on the rail, like mentioned earlier, use a hose connection first.

[ShelbyMopar89]

I bought the autometer with the sender and the wires to the guage. You guys relly think think thats too much weight for the rail? That thing does not weigh much at all?

[89daytonaTII]

it's not weight it's vibration

[87shelbyt2]

The reg. allows fuel OUT of the rail, NOT in. It's the last component in the system before it returns to the tank. Holding pressure before the rail would do nothing except make the pump work harder.
Sorry- didn't see the second page on this thread I figured someone would cover this...

[88BlueShelbyZ]

I gotcha, that makes sense. So the pressure before the regulator is actually the same as after, right?