Right now I'm kinda scared to go WOT...call me chicken but I want to make sure my fuel pressures are in the right range...not too high, not too low. With my vortech adjustable FMU, I can vary the starting static pressure, which is where it starts increasing pressure from. I dont' want to end up running 5lbs of boost making my FMU increasing fuel pressure over 100 psi (cause I think the pump can't sustain a high flow at that psi).


So I have a few questions...

How fast does boost build at 1/2 - 3/4 throttle? none? never? Is boost only when engine under load?

What should the EGTs be? What should the normal EGTs be (stock)?
Right now I get about 700C during cruising.

What should the correct fuel pressures be @ 5 psi? @ 7 psi? @ 9 psi? (w/ stock infjectors)


ok...enough rambling for me for now!





l e o n

>Right now I'm kinda scared to
>go WOT...
First off going WOT is a lot better because your ecu will read WOT and allow the injectors to spray at full potential.
Otherwise building at partial throttle will cause a leaner mixture.

>my fuel pressures are in
>the right range...not too high,
>not too low.
Driving your car at partial throttle will not affect fuel pressure.. take your to the limit, and watch A/F & EGT !

>I dont' want to end
>up running 5lbs of boost
>making my FMU increasing fuel
>pressure over 100 psi (cause
>I think the pump can't
>sustain a high flow at
>that psi).

The only way this would happen is if you actually crushed the top "solenoid" part of the FMU in order for the solenoid to open wider and create higher pressure.. (So you're okay there!)

As for the fuel pump not pumping enough.. The fuel sits on the "pressure" side of the fuel rail. The FMU sits on the "return" side of the fuel rail. The return pressure will not effect the pressure side's pressure. However if your fuel pump is crappy it will not flow enough fuel to fully pressurize the FMU.
You should not run into any problems with an aftermarket fuel pump and the FMU..

>How fast does boost build at
>1/2 - 3/4 throttle?
Boost does build at partial throttle !

>Is boost only when engine
>under load?
Yup

>Right now I get about 700C
>during cruising.
You're fine!


>What should the correct fuel pressures
@ 7 psi? = ~96psi
@ 9 psi? = ~104psi

LAST EDITED ON 31-Jan-01 AT 02:57 AM (PST)

I hooked up a boost guage to my hand pump and simulated boost into the FMU...

@ 5psi my fuel pressure reads ~65 psi... uhm something's wrong here I think...
@ 10psi it reads 90 psi

what gives...it's already using the largest calibration disk..is my pump having a hard time building pressure? I can get the fuel pressure to go over 100psi but that at like 15 psi...

or is something wrong with my FMU...??

I already set static pressure to 50psi..and according to the fuel pressure chart that came with it, I should get 85 psi @ 5 psi!



Also the fuel pressures dont' remain constant...they steadily drop back. Is this because I'm not using a constant supply of compressed air, but rather a hand pump?

My fuel pressure guage is hooked into the service port on the fuel rail, so the pressure readings should be right.

What's causing this? I've tightened the line from rail to FMU to make sure it's as tight as possible...so if it's not leaking there,

l e o n

Well the FMU raises fuel pressure upon boost, on top of the Static fuel pressure.. So you have to throw that into your equation too!


later!

>Well the FMU raises fuel pressure
>upon boost, on top of
>the Static fuel pressure.. So
>you have to throw that
>into your equation too!
>

But shouldn't my reading of the fuel pressure on the fuel rail take that into affect already?


>
>later!
>
>


l e o n