Fleemer

Car is as follows

Stock 1991 JDM FC3S. 120,000km. 100psi front and back.
Microtech lt10s, aem wideband, aem boost controller/gauge.
stock 550primaries, 800 secondaries.
walbro 255 fuel pump.

No BAC, ACV, thermowax etc. All removed.

Getting tired of the excessive fuel consumption. I know something is up. AFRs at idle are ~10.5 at cold start up and then even out at ~11-11.5 @ 900-1000rpm.

car runs retarted rich below ~4krpm with AFRs dropping down to 10 in vacuum.

My guess is the FPR can't handle the fuel pressure/flow. I'm waiting on my microtech dongle to come in before I try and lean it out some.

It is to my understanding the the AFRs should be no lower then 12.5 under vacuum.

Car is also not shooting fireballs despite running retarded rich. (wouldn't be complaining if it did :P)

Car starts fine and runs fine, no problems. I adjust the TPS with the light on the microtech. (it was off by a bit making the car buck below 2krpm) I thought this would fix my AFRs but it did not.

Car allways stinks like gas/rotang and I looked at the injectors and they don't seem to have leaky o rings. Car never floods so I'm pretty sure the injectors are not leaking either.

Car has been this way since I bought it. previous owner claimed it was getting ~350 a tank which is the norm fora stock tii but since my AFRs are retarted i usually just see around 250.. (km~~~)

AFRs in boost hold stead around 11.5/12 past 4krpm. Car sadly doesn't backfire on decel or throttle releif. (no cats, i have racing beat revii exhaust)

I'm just sued to my n/a shooting fireballs all the time when shifting and sometimes on heavy decel. Kind of miss that :P You'd think with the car running this reach it would, but maybe its running so rich that the exhaust doesn't get hot enough

RotaryRocket88

iTrader: (7)

Stock fuel rails/FPR? A walbro will drive fuel pressure up a lot with the stock FPR. In vacuum and around 0 manifold pressure is where it will be the worst. Once you get up into boost, the pressure difference is less substantial, but still there. Awhile back, I compared fuel pressure using a walrbo 255 versus a FD fuel pump and found this:

Walbro GSS-341
Idle: 46 psi
Atm: 48 psi
10 lbs. "boost": 54 psi

FD pump
Idle: 34 psi
Atm: 41 psi
10 lbs. "boost": 51 psi

Atmospheric pressure was simulated by removing the FPR vacuum line, and a hand pump was used to simulate 10 lbs. of boost. The only real way to control that pump is to have an aftermarket FPR. With the microtech, you'll likely be able to tweak the mixture enough to make it bearable at least.

Fleemer

stock rail and fpr+puls dampner.

Makes sense, as my AFR numbers seem richest then.

Previous owner said that it used to be 'great' on gas before. I'm wodnering if tis jus tthe stock FPR that is clogged/dirty.

Furb

iTrader: (2)

uuhm...
maybe i'm stupid, but since you got a microtech...

get it tuned..?!

-Crash-

The Microtech will not control the fuel pressure, it only tells the fuel pump when to start pumping fuel, when not to, and when to turn on the fuel injectors (simple explanation)

That is the job of the FPR (Fuel Pressure Regulator) on the fuel rail, not everything on cars is controlled by the ECU, stock FPR's run off of how they were calibrated from the factory, so when you change to a higher flowing fuel pump it becomes more than the stock FPR was designed to handle. This results in higher fuel pressure.

And no you’re not stupid, you just didn't know, and now you do.

RotaryRocket88

iTrader: (7)

The previous owner of my car said it would get "high 20s" on average . It sounds like your previous owner is a liar as well.

Tee a gauge into your fuel feed line, and duplicate what I tried. You'll probably get some fairly similar numbers. I can't see how an FPR would get clogged when it has gasoline running through it constantly. Gas is a great solvent, and it's not like there are rock-sized particles getting past the fuel pump sock and the fuel filter.