Having fuel leaning issues... bad fuel pump? please read
 

My FD is tuned in with a PFc by BDC. It used to run 11.2 at the leanest. i noticed it leaning up top over the past few months. I changed the fuel filter and it still seems to be leaning. heres what it does. I see lower 11's until around 6500 then it gradually leans until red line, but the leanest i see is 12.2 Which is way too high for my liking. I tried to fatten it up some with my aeromotive FPR and I noticed something else wierd. The most pressure I seem to be able to get it to is about 43PSI. It will not go any higher. I tried to drive around like that and it was cutting out (way too rich when it sees boost). so I turned the adjustment lower and got it back to where it was. It is a bit fatter under normal driving and in the mid range, but still leans up top. this is at 12 psi. Some times when I start her up she is a tad hard to find throttle, and I here a whining noise coming from the rear (which i guess is the pump). i rev it, and it flattens out and the whining goes away. Is it possible my wide band sensor is going bad? or possibly my fuel pump? I have a supra intank 255 pump. What does this sound like?

mods:

stock non-seq twins
streetport
1600Cc 2nds
550cc primaries
supra pump
FRP-aeromotive
PFC, tuned by bDC
full 3.5inch turboback
fmic
twin intakes
bunch of other stuff, but these are what matter

anyone?>

Yes you need a new fuel pump asap.

pressure should be 60 psi up top not 40.

no, its 40 psi at idle. it does raise. but at idle, i cant get it to raise up.

Are you keeping track of the ambient temperature changes? Colder temperatures could account for the leaner mixture.

If that is not the case, the fuel pump is suspect. I lost an engine for exactly the same reason. My stock fuel pump leaned out at RPMs over 6000, unable to deliver enough fuel. Once installed a new aftermarket pump, (and a new engine) I had to dial way back on the PFC at high RPMs.

Albert

Well, we have had 60-70 degree temps here the last month or so. I dont think its cause of that. i wish I had a remote fuel presure gauge so i could monitor the fuel pressure while wot. anyways. I think I am going to get a new fuel pump. I think my wideband may be saving me a motor at this point. With the new fuel filter, i took that out of the equation. the only thing i can see it being is the pump on its way out.

well, my other question is: when i start the car, should it whine from the ful pump area and have a ruff idle until i rev it once. It flattens out after that. it does seem to be a fuel pump t me.

also, How likely is an aeromotive FPR to fail? As I stated, I could not get the fuel pressure to raise at idle above 43psi. it should be able to to oust 60 if i wanted it to at idle. but agian that could be because the fuel pump wont let it.

You don't need the pressure any higher than 40 at idle. However you want it up around 60 when you climb higher in the rpm range.

No your supra pump should not be making any significant noise.

Do the fuel pump pressure tests as described by Mazda in the FSM.
The URLs for the manuals are listed above in one of the stickys!

The pump, speed relay, speed resistor, or the stupid nylon/"O" ring seal in the pump assembly could be bad.