I finally got the stock regulator out and tried to set the fuel pressure. I got the static to 38 psi like I wanted. Then I hooked up the vacuum hose w/ the restrictor installed (tried it in both directions) And it idles at 22-24 psi. No matter what I do to the vacuum screw on the regulator, the pressure will not move. Am I doing something wrong again?

What do you consider the "vacuum screw?"

It's not the screw that's plugging the side (labeled vacuum) of the SFMU. It's the very top-centered silver colored screw that's adjustable with an allen wrench.

You will probably need the dark colored spring inside the SFMU to adjust the idle pressure as high as you need it. (47-55 psi)

I thought the top one was just for static pressure w/ no vacuum. I adjusted that and got the static pressure that I wanted. In the instructions it sounded like I was supposed to turn the "vacuum" screw on the side but like I said it doesn't do anything. I want lower pressure since I have 315cc injectors. Right now at 38 static and 24 idle it runs fine. .96 Volts at WOT. I wanted to set idle to like 28 psi so I shouldn't have to change the spring. But I don't want my static to go up a lot.

The vacuum screw seems to be pretty useless for us. You'll just have to change the static adjustment to change your fuel pressure under vacuum.


Corbin

'95 ESI-T
HRC+FMIC+ETC...



Gimme fuel...Gimme fire...Gimme that which I desire

Ok well it was running fine. Then I checked under the hood and it was at a constant 60 psi no matter what I do to the static screw. Then I checked the next day (today) and it's sitting at 80 psi idle pressure. Runs like complete crap and the static screw is almost all the way out. Anything it could be? Maybe a pinched return line? That's all I can think of :/

Have you changed out your internal spring yet?

I've switched the disk but not the spring. I thought the spring was just for higher static pressure. Mine is too high already. Do I need to change it?

No, I'm just curious to see why you have the screw turned all the way out.

If I were you, I'd turn on the car, and during idle, I would turbo the screw IN until you reach 47-55 psi, and just leave it there. I know it's already too high, but that might be for other reasons. But try playing with it some more by screwing it in. I remember with the higher pressure spring in my application, I still have the screw turned in a good deal to attain the pressures I was seeking.

If this doesn't work, You might start suspecting your fuel pressure guage as a possible culprit or maybe a pinched fuel return line causing excessive pressures.

I had the static screw down pretty far and it ran awesome for like a day at 40 psi static and 22 idle. Now no matter what I do to the screw it won't change. I have a mechanical gauge screwed right next to the inlet on the sfmu it was reading ok and now it's reading 80 and the carruns like crap so I think it's reading right. I also have an electric in the car that never has read right so I don't even bother w/ it. I know it is running very rich even w/ the screw all the way out. I'm getting over 1 V and it bogs so bad at anything over half throttle. I'm going to redo my return line tomorrow and hopefully that will fix it.

Well in case anyone cares I redid the return line (switched from rubber fuel line to aluminum hard line) And it's back to normal now. Don't know if the hose was kinking or collapsing but it seems fine now. Thanks for the replies.

Glad it worked out. :-)

Just gotta remember that everything AFTER the fuel rail and injectors (that acts as a valve) can work against the fuel pump and cause your fuel pressure to rise higher than you like.