ledesordre

iTrader: (9)

Question for you veteran guys:

Have a build going on and trying to get a fuel pressure issue under control..
---Aeromotive 340 LPH pump in 99-02 plastic tank w racetronix wire upgrade kit, stock rails stock 98 injectors otherwise


I have a Aeromotive 340 LPH fuel pump setup with the Racetronix upgrade wiring kit. I am otherwise running stock fuel system with stock 98 ls1 injectors. Currently my on the RAIL fuel psi is reading really high, like 78 PSI. Obviously I need to get this down. Is my fuel regulator messed up? I have my Aeromotive pump in the stock 99-02 plastic fuel tank bucket system and running the stock regulator.

Is it possible that I can somehow dial in the voltage going to the pump to help achieve a 58 psi at the rails fuel pressure? That way, I think that if I were able to lower the amps going to the pump then I could maybe dial in my system or at least see if my regulator is working. Is this what the MSD fuel booster does? I'm a little confused on it.

Is it possible that my stock 99-02 fuel regulator is kaput? or maybe there is a check valve problem in my Aeromotive pump.

I ordered a 99 Corvette regulator/filter combo that I am planning on pumping inline near the stock T-block in the rear. I am hoping this helps to solve my PSI problem but I also just read that in order for the vette filter regulator can only handle a certain limit of PSI that I may be close to already.

Anyone have any input on this? thanks..

turbo build under construction..

TPIIROC

iTrader: (1)

Maybe I am out of line but it sounds like one of two things is happening.
1. Your fuel regulator is not working properly.
2. Your return line is too small causing a restriction raising the pressure.

fastsspr

iTrader: (49)

Interesting case because now we can see what to spect when using aeromotive 340 fuel pump !

Lonnies Performance

iTrader: (16)

I doubt you can turn the voltage down enough to reduce the flow sufficiently.

As for the Vette filter, I'm not sure it will be much better... but I cannot give any hard facts to support this.

If you really need that much pump, you should already be considering a front mount regulator to provide proper pressure control.

The return line is not the problem... the factory regulators are not designed to flow this amount of fuel. Even a 255lph pump is at the limits of the regulator to properly control the pressure at low engine demands.

98BLOWNZ28

iTrader: (10)

so all he would have to do is run a fuel pressure regulator before the rails to lower the fuel pressure and he will be good?

MeentSS02

iTrader: (11)

i'd put it after the rails, but yes.

98BLOWNZ28

iTrader: (10)

i dont mean to highjack, but why after the rails?
wouldnt it be placed from the stock feedline, to the fpr, and then to the rails?

MeentSS02

iTrader: (11)

The regulator acts like a dam - you set the pressure, and everything behind the dam maintains that pressure. The excess is bled off and returned back to the tank.

TPIIROC

iTrader: (1)

This

realsquash

iTrader: (1)

That's not really how it works. The regulator is just a self-controlled valve that bleeds of excess pressure and sends it back to the tank. You can put it anywhere in the pressure line - before the rails, after the rails, in the fuel tank, etc. It responds better when it's after the rails most of the time though.

So just like anything else in this hobby, one new shiny part tends to reveal the limits of the next one down the line. That is the FPR in this case. I'm confident the stock FPR won't bypass enough fuel volume to hold steady pressure at idle and cruising speeds. At WOT it will probably pull fuel pressure down to what the regulator was previously set to.

This is not due to the size of the return line connected to the FPR, it's the size of the orifice that the valve in the regulator has to pass gas through. The pic below is of a "700HP" regulator. The return orifice is only 0.135" or so, even though the return port is machined for -6 fittings. That little hole has to flow ALL of your fuel pump's output when the car isn't running, and nearly all of it at idle and cruise. The result is the fuel pressure goes up and you can't bring it down, or it's all over the place. Your stock FPR is going to have a similarly small orifice. I ended up replacing this thing with a big Magnafuel regulator with a giant return orifice.

FWIW I also have experience running those Aeromotive 340's, two at a time, one at a time, and now two with a PWM controller I built. They seem to work with PWM, and I've got my car running two of them as slow as I can at cruising speed and they are fine. With the regulator in the photo and one pump at full speed the fuel pressure would go up 20psi or so at idle. Once I figured out what was going on I found that with both pumps spinning I could shoot gas about 20 feet across the shop out of the bottom of that regulator.