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What to do with STOCK intank regulator when using adjustable external one?
The car:
2000 Trans Am on E-85
Dual 255lph Walbro GSS340 pumps, BUT swapping to dual Aeromotive 340lph now that I run straight E-85 flex fuel.
Dual Racetronix Hotwire kits
Stock lines, stock rails, 60# Siemens Deka injectors
Aeromotive adjustable pressure return regulator mounted at stock fuel filter location
Also has stock, intank regulator <<<----
Primary pump feeds engine only
Secondary pump wired to turn on simultaneously with nitrous solenoids & nitrous retard
Those of you using an external return style fuel pressure regulator...
What do you do (if anything) to the functionality of the factory, in-tank fuel pressure regulator??
Should it be gutted out, or otherwise removed from the mix?
For 2 years, it's been used as a redundant regulator, I guess you'd say...
I ask now, because I'm swapping out the Walbro pumps due to them not (supposedly) being E-85 compatible, which may or may not be the culprit in the car's current state...
On my 3rd tank of flex fuel, and after driving 45 miles or so to dragstrip Sunday, then making 6 passes...issues on the way home, fuel pressure dropped 20-ish psi, down to 40 causing 5-15% lean (lambda) according to my wideband.
I believe one (or both) of the two small hoses from the pumps, to the "T" at tank outlet, have failed again because I can force the 2nd pump to turn on, and that is the only way the fuel pressure will go back to 60psi. Still drops immediately upon turning KEY OFF...This has happened twice in the past, and I recently read that the Gates submersible hose is known to fail...
Anyway, the fuel feed issue is being addressed this week, and just need to know what I "should" do, to the stock regulator, while I am right there anyway??
You can't run regulators in series. The pressure to the rail will be of the regulator that is set the lowest, making the other redundant.
So, do you have a suggestion? I don't think I'd be able to trust the stock one (alone) to control the pressure of a 340lph pump (especially when BOTH are on), but if it CAN, then I will, and will re-configure a T where the stock one was.
The Aeromotive regulator was a leftover, from when the car had a turbo and needed the extra 1:1 fuel pressure spike that it would give. It no longer has any vacuum/boost going to it, obviously, as it's not needed for that anymore.
I was thinking the Aeromotive was the better option, as a single regulator, but no idea how to take the other out of the equation...
I know I could "pop off" the silver colored diaphragm housing, but that would have fuel spraying all over the place. I wonder if there is a spring and diaphragm inside of it, like my Aeromotive one has? If I went that route, just remove the spring, check ball, whatever, and use it as a empty housing to direct the fuel back down into the bucket like stock?
Turns out the two hoses were not split...just pushed off of the "T" that connects the 2 pumps to the fuel outlet...I still plan to swap pumps, since the Aeromotives are E-85 safe
I cut the black housing off of the metal rod. I installed a Racetronix 340 kit and it came with a return hose that clamps to the end that will be exposed when you cut off the housing. I think I have photos at home that I can post this evening.
I cut the black housing off of the metal rod. I installed a Racetronix 340 kit and it came with a return hose that clamps to the end that will be exposed when you cut off the housing. I think I have photos at home that I can post this evening.
Update:
Installed the new 340lph Aeromotive Stealth pumps this morning.
With BOTH regulators still in the mix, but the Aeromotive regulator's pressure adjustment screw totally backed out (ie; non-functional), the pressure would not go lower than 65 psi.
Popped the whole bucket assembly back out
Dis-assembled the factory regulator, so that it was non-functional
Aeromotive back in the mix, and fully adjustable, working great by itself.
I didn't concern myself with how, or where, the return fuel exited the gutted stock regulator and back into the tank, since the factory bucket has long ago been butchered and has not been an actual "fuel bucket" for a long time anyway.
FWIW, I've never really had any issues with a Walbro, but they advertise them as not being E-85 compatible...
As a side bonus, the Aeromotives are actually quieter than the Walbros were...I guess that's where the "Stealth" name comes from, lol
Racetronix and a few others make billet plugs tht block off the regulaters. Ive seen them used on truck intake oem return style rails. I think they fit the in tank regulater housing as well. Worth a checking out!
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What to do with STOCK intank regulator when using adjustable external one? 
