Not sure if I should post this in here or in the LT1 sections, but here goes:
Did a search but didn't come up with anything that seemed to answer my questions...

On the S/C car, at idle my fuel pressure holds rock steady, no fluctuations. The pump seems very noisy, and seemed to "break up" a bit until I replaced the fuel filter with a new one, now just noisy. Can drive under light throttle no problem at all, but if I get on it past about 1/3 of the way, the fuel pressure drops. If I floor it completely, it will drop almost to 0 until I let off again.

Haven't done a fuel pump replacement on a T/A or Camaro yet, but I'll be looking at a write up as soon as I find one. Any comments/suggestions there would be most appreciated. I'm thinking either the pump needs replacing, or the "sock" filter is clogged. Car sat for several months as the previous owner fried the PCM before I bought it from him. Also, current program is my own VERY slightly modified from stock setup, could that make much of a difference? Is there any way to check the operation of the in-line "booster" pump?

Additionally, I'm having idle problems. Currently I'm running in Speed density mode as if I try to run it in MAF mode I get a MAF failure, and my PCM reads 473 g/sec continously. In SD mode, my idle won't stay where I set it, instead it falls off and tries to die. Keeping my foot on the gas slightly keeps it running PERFECTLY. I've seen some people recommend drilling the TB blades to let more air in. IIRC, that is ONLY if my IAC counts are maxing out HIGH (160) correct? Could the MAF not being available and my VE tables being for a stock car be making this problem? I'll be putting my stock MAF from my other T/A in it sometime soon to verify, I'm just trying to get ideas for now.

Lastly, I'm wondering what kind of power I should be expecting once I put everything through my 6 speed. One of the previous owners made 420 to the wheels through a 4L60E and the 9". I'm thinking since it still has the FMU on it, that if I run straight 1:1 fuel pressure and tune for it, I should be able to make even more power yes? I would like to get it to 500-550 at the wheels. I'm thinking that just putting it in front of the 6 should net me another 20 or so to the wheels...

Sorry for the noob questions.... I've slowly been building my knowledge base on the FI LT1's, but didn't expect to have one until 2009. But you just can't pass up a great deal....

Jonota

 

I am about 99% sure you have a fuel pump problem. First I would remove the inline pump and see if you still have fuel pressure problems during normal driving. Don't do any WOT runs without the inline! If your fuel pressure is still dropping at medium throttle then you will need to replace your intank pump. If it is not the inline pump needs replacing.

Since you said it was noisy I would think that the inline pump is bad or has faulty wiring. Intank pumps make very little noise when they go bad.

BTW I wouldn't drill your throttle body under any circumstance.

 

Is your in-line fuel pump working (blown fuse?), how about you FMU?

 

I'm not sure. I'm still not technically allowed to work on it (wifey's rules until my OTHER two projects are gone). I THINK that the fused wire I reconnected in the engine bay was the power line to it... and I hear LOUD pump noise when priming or when the car is running. As for the FMU I don't know whether it is or not as FP drops off as soon as I get throttle... I've only seen about 3 psi on the gauge before I let off (fraction of a second of throttle).

Jonota