I have just finished up breaking my new motor I rebuilt. It is a 89-91 non-turbo, and I ported the primarys and secondarys, removed the sleeves, devcon epoxy to smooth transition of the 5th and 6th ports. I am using TII rotor housings, that I street ported as well. The intake was ported in some area's around injectors and ect to free up some restriction. After break in it seems to lean out at high rpm, and it cuts out entirely at 7.5k rpm. It is all stock otherwise except for a kN filter. Exhaust is coming tommorrow, but I dont think this will make a difference in fuel starvation. the Injectors were cleaned and balanced, but are stock , the fuel pump is stock too. I read all of Icemarks setup and he seemed to richen up on top end, but I know for sure that mine is starving. Other people say they leaned out after the porting. IS my fuel pump bad? Or are the stock 460cc too small? Fuel filter is new too, that is not it either. If anyone has experience, let me know! Thanks!

 

The stock 460cc injectors should be fine unless you have some massive porting. It could be that you arent getting full voltage to your fuel pump.

 

get access to a wideband to be sure, if so either get a new pump/ raise the pressure, or get a new pump and put T2 secondarys in, and tuneboth down with a S-afc

 

How do you know it's lean?
How do you know it's insufficient fuel delivery?


-Ted

 

Ted beat me to it. Your mods are well within the capabilities of the stock fuel system. You need to prove it's lean (if it even is) and then find out why instead of just throwing unnecessary parts at it.

 

Hmmm, its gonna be hard to access a wideband, but I will see what I can do. Thanks for the help!

 

You don't need a wide-band to do this.
Get a DMM and probe the O2 signal wire and a good ground, and tell us what kinda voltage readings you are seeing.  The signal should be between 0 and 1VDC.


-Ted

 

I thought my 89-91 was leaning out as well.... got it on a dyno with a wideband... NOPE.. it was hitting 10's on the A/f at 7K rpm....... this was after a racingbeat exhaust and a K&N filter with a cold air box.!!!

 

Like everyone has mentioned, the stock fuel system is more than enough for ~180 FWHP. However, this is under ideal conditions with the entire fuel system running at tip top shape. As we all know these cars are 15-18 years old, so it's hard to expect your fuel system to still be at 100% after all those years.

My 86 is similar to your setup: S5 street port, headers, intake, no cat, S-AFC, etc... On the wideband I was running out of fuel around 7000 RPM. (Hitting 15's on the wideband!) The S-AFC was at +25 and it wasn't making any difference. I switched to 550 injectors in the secondaries and I added an S5 TII fuel pump.

After those changes, I was able to maintain A/Fs in the 12's.

Question:
What ECU are you running? S4 or S5? If you have an S4, then you are hitting the Rev-Limiter at 7500.