How does it work? If I disconnect the vacuum? If I leave the vacuum line?

This info I need to know in regards to my adjustable FMU....

l e o n

With the vacuum hose on the stock regulator diconnected, your minimum fuel pressure should be 47-50 psi. The adjustable FMU should only raise fuel pressure from that point. If you leave your stock regulator vacuum hose connected, it will vary your minimum fuel pressure from 38 to 47-50 psi depending on how much vacuum it sees. Then the FMU would be trying to vary the pressure at the same time. Save yourself some tuning headaches and disconnect the vacuum hose to the stock regulator. If you're really concerned about the stock regulator. Take it off and examine it. Maybe you can tear its guts out and keep it from regulating anything . Its only held on with a snap-ring .


Corbin
'95 ESI-T
HRC + FMIC
http://members.nbci.com/cbehnken/

Would there be a problem if we ran the car with a minimum fuel pressure of 47 psi? What would happen? End up running a bit rich when there is alot of vacuum?



l e o n

I have a 98' and my minimum fuel pressure is always 47 psi if that helps alleviate any of your fears.

Go with Corbin's advice and just disconnect the vacuum hose.

Jason
98' Eagle Talon ESi-T
Mitsu Super 16g Turbo(HRC)


http://springfielddsm.homestead.com/JasonsPics.html

where did u tee in your fuel pressure guage?

l e o n

On the "out" end of the adjustable FPR.

Jason
98' Eagle Talon ESi-T
Mitsu Super 16g Turbo(HRC)


http://springfielddsm.homestead.com/JasonsPics.html

Since my stock FPR will cause my min fuel pressure to be at 47-50psi, I don't see the need to plug a vacuum souce into the adj FMU (since it won't be able to lower the pressure).

So should I still use the intake manifold as the vacuum/boost source, or could I run it directly off of the turbo? I remember that if the FMU is hooked into the turbo, we get less of a "reg lag..."

What do you guys think?

I would just hook the FMU up to the manifold. I'd figure the manifold pressure is the most important one. Its after the pressure loss in the IC/piping, after the BOV, and after the throttle plate. Thats the air thats actually going into the engine. I don't recall ever having a problem with the FPR reacting too slow.


Corbin
'95 ESI-T
HRC + FMIC
http://members.nbci.com/cbehnken/

Hmm, I wonder if the Bell adjustable FMU has a different response time than my Vortec adjustable FMU?

I just don't want to run lean even for a very minute period of time...take a look at this thread:

http://www.2gnt.com/dcforum/DCForumID16/135.html


Hey Corbin, can you adjust your fuel pressure below 47-50 psi?




l e o n

I'm not sure what this is an indication of, but I actually can make my fuel pressure dip pretty low <~40 psi>. I'm not sure if my fuel pressure gage is reading low or something else is going on. I shouldn't be able to get it that low...assuming that the stock regulator works like I think it does. When I get my car back, I'm going to remove my stock regulator and check it out . I'll check my fuel pressure gage too. I'm also really considering an AFC and injectors. I've got so many plans for the coming weeks...I'm dying to get my car back.


Corbin
'95 ESI-T
HRC + FMIC
http://members.nbci.com/cbehnken/

Correct me if I'm wrong, but stock regulator should cause fuel pressure to be at 47-50 psi at 1 atm (vacuum line yanked off) ??

And with my adjustable fpr hooked serially from the stock FPR into the return fuel line, fuel pressure cannot be lowered...right?

l e o n

Thats the way it "ought" to work. I'll soon figure out why I can make mine dip to 40. My fuel pressure gage may be reading too low. I'll check it out when I get my car again.


Corbin
'95 ESI-T
HRC + FMIC
http://members.nbci.com/cbehnken/

I can't seem to make my fuel pressure go above 50psi with my Vortec SFMU....werid..


l e o n

i can actually run out of fuel pressure. boost until the pump just can't supply any more, then all the pressure just blows through the injectors, sputter, sputter, pop pop.

-DarkOne
I'm so bad, i should be in detention.

what do you mean?


l e o n

The pump, which we now know is the wrong one for our application, simply put, might not be flowing enough at 50PSi to raise the pressure any more. I don't have a fuel pressure gauge, so i don't know, but it's highly likely.

-DarkOne
I'm so bad, i should be in detention.

Well all I can say is that when I simulate boost to the FMU (useing a bike pump) I see the fuel pressure go up. But when I turn of the pump, the pressures drop rapidly back to 0, so I definitely think the pump is having a hard time maintaining pressure.


l e o n