saad601

Hey Guys,


I have very low fuel pressure reading from my recently installed fuel Pressure gauge which is result in leaner AFR and i cannot crank up the boost. Base Pressure at idle is at 25 PSI where as when at boost, it climbs upto 50 PSI MAX

Im running a 30R with 880cc Injectors, a walbro(new) but i cannot take it above 22PSI as im getting AFR's of 12.6-13.


Ive Checked all the fuel lines and injectors seals and there's no leakage whatsoever, can anyone guide what the problem might be??

AlwaysinBoost

iTrader: (17)

are you running the OEM FPR? 25psi is way low, as you already know. try pulling the vacuum line off the regulator as the car is idling to see if the FP jumps up. IIRC it should be around mid-high 40psi when the line is off the regulator. Just don't forget to put it back on.

the OEM regulator should increase FP as boost climbs @ 1:1 ratio. so if you have 25psi base fuel pressure and the regulator sees 10psi of boost from the manifold it should show 35psi of fuel pressure. unless you have an aftermarket FPR, they sometimes have a base pressure set screw and if its a RRFPR (rasing rate fuel pressure regulator) it has an adjustment knob to increase the rate the FP ramps up with boost.

saad601

thanks for the reply, but in my thread i forgot to add also that i have a Aeromotive FPR Installed+ i have already done what you've written above ( tightening the FPR) but the fuel pressure reading has not increased

AlwaysinBoost

iTrader: (17)

so it is an aftermarket regulator... ok, are you running an aftermarket fuel rail and do you have the regulartor installed on the return side, not the feed side? I used to have an areomotive FPR and IIRC the adjustment screw is on the top of the unit. turning that screw should increase/decrease pressure. if it doesn't the unit might be broken. there is also a port on the side that should be hooked up to a source that sees boost and vacuum (manifold is perfect).

WHTEVO

iTrader: (18)

There is no exact fuel feed or return side of the fuel rail. You can use whichever side you choose.

How do you have your fuel lines piped to your regulator? You should have your fuel from say the end of the rail going into one of the side ports of the regulator, and your fuel return line coming from the bottom of the regulator. If you don't have it that way, and have the return just coming back out the opposite side that the fuel is going into, then that is your problem.

There are some Aeromotive regulators that have bad machining on the seat inside which have been known to cause fuel pressure issues as well.

Good luck.

Aaron

saad601

well, i am a bit of a noob here, i can tell that i have a Aeromotive Fuel Rail Installed and the FPR is installed on the left hand side of the Car, I.e passenger side.


Ive tried to tighten the FPR and the Car goes pig rich at idle which proves that the FPR is working, but the Fuel pressure sees no improvement.

WHITE EVO>>> could you explain correctly about the wiring of the regulator, i dont understand what ur trying to say.

WHTEVO

iTrader: (18)

Not the wiring, but the way the fuel lines are installed on the regulator. You should have one line going into either side of the regulator, and one coming out of the bottom. The one off of the fuel rail should go into the side, and the one from the bottom is the fuel return to the fuel tank.

Aaron

05blue8

iTrader: (28)

It goes like this -

Fuel line from tank to driver's side of the rail, fuel goes in, through injectors, out passenger side of rail to the fpr which regulates how much stays pressurized. There should be a line into the rail on the driver's side, a line out of the rail on the passenger side (for stock the regulator bolts right up to the railing) then if a line out that line connects to the aero fpr. That aero fpr has a vacuum hose and also has a fuel line that goes back to the tank.

Does your pressure change when you remove the vacuum line?
What is your pressure at 5psi of boost?

saad601

Well jst took a ride again...n checked the lines of the FPR...it. Is fitted as you guys have said...lines connecting either side of it and 1 line connected to the bottom.

The base pressure is only 25PSI, I'm running only 21 PSI which takes the gauge to 40 Psi max in 3rd gear when the car gets heated up.

Just don't know what to do?? Any other suggestions?

saad601

anyone?

05blue8

iTrader: (28)

Swap out your fuel pump, that only takes about an hour to do and it's cheap. You said your walbro is new but perhaps it has some issue with it. There's no reason at idle your fuel pressure should be so low. That will definitely throw everything off. Did you install it or did a shop? Maybe the o-ring isn't seated so the pump is pushing fluid but it's spraying back into the tank instead of up the line...I've heard of those getting pinched before and even done it to an injector myself a few times. It should be coated with oil so it slides in easily and seals.

binky

iTrader: (11)

There is a a nut that can be loosened at the top of the FPR, loosen it.

While the vacuum line going to the FPR is disconnected, start the car and turn the screw until you reach 43.5 PSI, this is your base fuel pressure.

Tighten the nut and you'll be fine.



-Bink

05blue8

iTrader: (28)

Good call, I shouldn't have assumed it was correctly adjusted upon install...sometimes I give people too much credit. I thought the base pressure was right before, he got a new fuel pump and the issue happened...oops.

saad601

Thanks binky for the input, what I should do is, loosen da nut on top of the FPR, and which line should I disconect? The feed line going into the intake manifold or the the one going into the fuel rail?

05blue8

iTrader: (28)

Do NOT disconnect the fuel line, only the vacuum line. Make sure you loosen the nut before turning the screw or it will strip it out very quickly.