1SIKZ31

iTrader: (5)

Hey guys...
Turbo LS1 76mm...

Heres the fuel system:

SINGLE Walbro 255lph <-- I know I know....
-6AN from the tank to the Aeromotive Regulator
Aeromotive A-1000 -6AN 1:1 FPR
-6AN return from the regulator to the tank
-6AN hose from the regulator to the Stock LS1 Fuel Rail.

With the Aeromotive regulator's base-pressure set screw cranked ALL the way down to full-tilt and the fuel pump ON at 13 volts... We get 50psi fuel pressure with the car idling. When we stab the throttle Under no load just sitting there the pressure INSTANTLY drops 20psi to about 30psi... each and every time... and happens instantaneously when you stab the throttle..


So we re-wired the fuel pump, 10 gauge wire to a relay triggered by the factory wiring..
Now... base pressure at full tilt is 70psi... much better...
BUT!... same issue! stab the throttle.. loses 30psi!
40psi!

We have the fuel pressure readings tapped at both the Rail AND the fuel pressure regulator, both show 100% same pressures. That rules out the gauge.

We swapped regulators and the same issue 100% no change. (the other regulator was removed off a RUNNING car....

Fuel filter is a 100% brand new -6AN fuel filter from summit.

We pulled the fuel pump assembly and the rubber hose is NOT ruptured and no fuel leaks are present anywhere including inside the tank (no by-passing occuring...)
The strainer is not clogged and in-tact.

half tank of fuel in the gas tank too!

So we did an experiment... we pulled off the feed hose at the regulator in the engine bay, turned off the fuel pump and put fuel in a container... its coming out like a faucet turned on at half-speed...
Not normal!!!

The ONLY culprit now is the fuel pump... The thing is, 4 months ago... it made 500rwhp and worked like a champ!

We ordered a Aeromotive 340 Stealth. How much power should this pump support?

Anything else we missed on this diagnosis of our fuel issues?

Exidous

iTrader: (11)

You could be looking at a flow restriction with the -6 or the 255 just doesn't have enough in it.

You can do a little math too if you like. The 255lph is 56.1 gallons per hour or 341lb/hr. Your 8 80lb injectors can flow 640lb/hr. I'd probably say two 255's in parallel would be fine assuming the -6 doesn't become an issue.

I use the stock turbo supra pump(300LPH) in the car below and it was a direct fit. :-p It's really quiet and easy to get too. If this is for your monster miata, it may fit.

After doing some more napkin math it looks like the -6 would be fine. The pump just has to have the necessary head to "push" through the line losses. This shouldn't be more than a couple PSI. I use stock 3/8"ish line with no issues or drop. I use corvette returnless and get a solid 58lbs.

Question, where did you put the turbo?

1SIKZ31

iTrader: (5)

Interesting. Makes sense!
Appreciate it!

I wont be near the limits of the 80 lb'ers... probably 60% duty cycle max...

Hopefully the Aeromotive Stealth will take me to 600rwhp... I doubt it though.

Only other things that sucks, is that even is the Stealth DOES get me there... it will be near its limits, rendering it un-reliable...

Thanks for the reply.
Its in the back.

Old Geezer

iTrader: (3)

"Fuel filter is a 100% brand new -6AN fuel filter from summit."
So, what filter was in the system when you had no problems??

1SIKZ31

iTrader: (5)

the old set-up was a factory C5 corvette regulator with -6AN fuel disconnect fittings on it....

so the return was mounted near the tank in the back of the car...

Oh and I never had a fuel pressure gauge on the old set up so who knows... lol

Exidous

iTrader: (11)

Very nice. I've always thought about going FI on the RX-7 but could never decide where I'd want to put the turbo. Not really a big fan of the A/C delete that Hinson does.

conan

iTrader: (5)

Do you have room to run 2 in tank pumps. I tried a lot things on a singe walbro pump... Hot wire kit, Kenne bell boost a pump, all would loose pressure around the 500 hp mark. Got myself a double pumper from Lonnies performance and never looked back. Fuel pressure is always at 60 psi.

Old Geezer

iTrader: (3)

the Op problem doesn't get close to the magical 500HP level. He hits it, and the psi goes in the toilet....I don't think the problem is insufficient fuel pump.

"Now... base pressure at full tilt is 70psi... much better...
BUT!... same issue! stab the throttle.. loses 30psi!"

Ollie8974

From the description above, I would be inclined to say the max. pressure capacity of the regulator is not high enough. The max. psi of the regulator on a fuel injection should be 100 lbs. It should also be vacuum referenced for a NA engine and pressure referenced for a boosted engine.
The correct regulator should maintain the set pressure under all conditions.

Old Geezer

iTrader: (3)

"It should also be vacuum referenced for a NA engine and pressure referenced for a boosted engine."
Gotta be careful with this advice....
An "NA" app would be vac referenced only if the injector constant table is set to all the same value.

70lsgto

iTrader: (2)

I had a walbro set up but after advise from the guy that was going to dyno my car i went with a magnafuel system with a boost ref. regulator and pump good for 2000 hp overkill but dont have to worry about starving for fuel...piece of mind i guess, the engine is a 2005 ls2 with a turbonetics 76 on it .