i was wondering when setting fuel pressure with an adjustable unit are you suppose to adjust it with the vaccum line at the regulator connected or disconnected..... because i adjusted mine with it all hooked up and its at 45psi but when i take the line off and plug it up its at 57 psi.... whats the proper way....

 

Gotta adjust it unhooked. Unhooking simulates WOT, which is where you want your given fuel pressure. Hook it back up and it'll drop, but open the throttle manually while under the hood and you'll see it creep back up.

 

57 unhooked is to high. Drop it down to 50 psi unhooked and see how it feels. Usually, at 57 psi your idle quality will start to suffer a little and you may actually loss a bit of power.

 

well alvin at pcmforless tuned my car and he says the best optimal fuel pressure for my build is 44 psi... im running 24 pound svo injectors... i always thought that you adjust fuel pressure with the vaccum line all hooked up. with it all hooked up its at 44 psi... when i take the line off the psi is almost at 60... so for the past three years i have been running a higher fuel pressure than i thought i was??? this would explain why i can smell fuel and it not running optimal like it should.... build should have abit more grunt to it...

 

so when i set it at 44 psi unhooked my gauge is going to read about 33 psi with everything all hooked up... is that correct...

 

Yeah, that sounds about right.

To a point you cCAN go too low or too high, but I'd say anywhere from 43 to 50 could be optimal depending what your car likes. I'm running right at about 45. Like Burnout said, I'd give it a shot at 50 and see how it feels. I'd also try it right at about 43 too, and see if there's a diffference. Play around with it. That's the beauty of the AFPR.

 

well i adjusted at 46 psi unhooked and put the line back up and wot is MUCH better.... pulls alot harder..... and my smoking went away.... i cant believe what a difference it makes... the reading shows 37 psi with it all hooked up but at wot its at 46 psi.

 

idk, with 24 lb injectors i had to lower my fuel pressure to 42.5 , then it pulled harder. when i got a new chip burnt i got it adjusted around the bigger 24lb injectors and then i just set my fuel pressure back to stock. 43.5

 

My car was already tuned with everything I got... I just never thought u would adjust a regulator with the vac line off... as a matter fact I re read the manual for the areomotive adjustable regulator and it does in fact say to adjust the regulator with the vac line off.. so its adjusted properly now and it performs much better.

 

Sweeeeeeet!

 

thanks everyone.....

 

From the above posts looks may we have trouble with fuel pressure after a fuelpump change on 91 3.1L V6.

Can someone tell me the exact locations where and how i can change the pressure? And which is correct reading for stock injectors on a 3.1l?
I dubt it was coming from the pump as is.
And the vac line on the regulator vas capped off while the adjustments are made? Or just leaved to direct air?

 

What fuel pressure do you have?

I'm not sure about the 3.1, but I can't imagine it's much different. I could be totally wrong, so double check.

.....as for WHERE you adjust, at least on the TPI, you have to install an adjustable regulator. Factory regulators are NOT adjustable. ...but it's really for fine tuning, or for aftermarket motors, etc. etc. On a stock engine, the non adjustable either works or it doesn't. ...and if yours isn't working, it shouldn't be too hard to replace.

 

....also, as I mentioned, the adjustment is for FINE TUNING at wide open throttle, to get optimal performance. That's why you remove the vacuum line, becase it simulates wide open throttle. ....but if you're having pressure issues at idle, leave the vacuum line ON to get an accurate reading from your pressure gauge.

 

i try to help on my brother on this issue:https://www.thirdgen.org/forums/v6/7...1-v6-3-1l.html
We both have 91 3.1L and i also i have 88GTA too.