lower fuel pressure under 27psi

[rpmguy]

Have any of you guys tried to lower the base fuel pressure under 27psi. What is the main restriction in the return. Is it the return line size or some of the fittings off the regulator or something small back at the tank. Want to run 40% with stock cal with low fuel pressure. Trying to get to around 24psi

[turbodaytona87]

You want to run +40's?

[Juggy]

dont see why you would want to run +40s on a stock cal???
there should be no restrictions in the return line?? stock is 1/4" i believe all the way back

its quite possible your regulator cannot dial down that low. lots of AFPR do not go down under 30psi, and combined with a better pump it can make things even harder to achieve lower fuel pressure

[rpmguy]

ok thanks, just wanted a little lower. car seems to run ok now.

Going +40 and old school fmu

[turbovanman²]

20 psi is about the lowest you can go and still maintain a decent spray pattern.

[rpmguy]

Cant seem to get any lower than 27, thought there might be a certain fitting or bend in the line somewhere that I can modify to get a few more lower

[turbovanman²]

Cant seem to get any lower than 27, thought there might be a certain fitting or bend in the line somewhere that I can modify to get a few more lower

Your maxed out on the fuel system per say, it won't let you go any lower due to the design of our fuel system. If you need less fuel, you going to have to run +20's or a new cal.

[rpmguy]

Just figured it out. The return line has some kind of anti air defuser in the tank. Just fixed it. This is on a 1990 car. Thought somebody might want to know. Restriction is not the regulator ( Im using GN regulator)

[shadow88]

Did you happen to take any pictures of this restrictor in the tank? I'm running a GN afpr with +40's on a stock cal as well, and I seem to be able to hit around 29 psi minimum. I just accept that it's a little rich at idle, but if I can lower it, I'd be pretty happy.

[rpmguy]

no pic. if your car is like mine should be an easy fix. On the fuel gauge sending there should be two steel tubes going in. Only one is used, and other has a cap. Switch the return line to the other tube (larger). may be a ----- as tube is bigger, or buy nice new fuel line and sealglide. I was able to kill the motor with ultra low fuel pressure with +40 and stock cal. :D

[turbovanman²]

Just figured it out. The return line has some kind of anti air defuser in the tank. Just fixed it. This is on a 1990 car. Thought somebody might want to know. Restriction is not the regulator ( Im using GN regulator)

All I've seen is a rubber cap with a slit in it, like a mini check valve?

So after doing this, when was the lowest pressure you could turn it down to?

[shadow88]

I'd like to know too!

[rpmguy]

I was able to turn down the fp to about 22, but that was maxed out. as the vacuum line would not drop it any more when hooked up.

But I scraped the low fuel pressure idea and the FMU, tried it and the fmu was just not going to work for me. No constancy in WOT fuel pressure. Tried the BEGI.

Now running more base fuel pressure with +40 and stock cal.

How are the TU 3 bar cals running.