I have a L05 (350 TBI) with BBC injectors in a car that was originally an L03. I realize that lack of power up top is to be expected from a motor that was designed for stump pulling, but this thing REALLY falls on its face around 3500, maybe 4000 RPM. It literally stops pulling completely, especially noticable in 1st gear. I probably have the original fuel pump, and the car has 172,000 miles. Have I likely taken this pump as far as it is going to go?

 

Have you tested the fuel pressure?

 

Fuel pressure is good at about 12 PSI, but I cannot really test this while driving around.

 

I remember somebody posting 17 at idle and 28 static for their TBI.
What flow are these "BBC injectors?"

Did you update the ECM?

 

get a fuel pressure tester, a wise investment, specially if you are into tweaking with your rig and it sounds like you do. get the tester and end the fuel guessing games.

 

BBC Injectors are 90# per hour injectors. I have an EBL set up with a custom PROM that I am constantly tweaking. I have a fuel pressure guage, but no way of looking at it from inside the car. I guess I should get a different one then and check it that way.

 

why cant you test fuel pressure in the drive way if you know the rpm range it is occuring in?

 

Because at idle and light throttle sustained RPM you are using like 1/100th of the fuel you use @ WOT sustained load. You will NEVER duplicate the fuel usage @ WOT and high RPMs in your driveway, unless you have a Mustang Dyno and can simulate WOT AND High RPMs.

I have run nearly stock TBI engines to 5,000 rpm easily when they are tuned properly.

I think the bottle neck is the original LO3 exhaust manifolds. There is power to be had even with a stock L03 in the exhaust.

Here is a screenshot of the Datalog of the internally stock 4.3 TBI that is in my brothers 1992 Chevy Astro work van. Loaded with about 1,000 lbs of tools at that.



https://www.thirdgen.org/forums/atta...z4-cam-wot.jpg

https://www.thirdgen.org/forums/atta...mph-cruise.jpg

This one is falling on its face at about 4,200 rpm due to fuel issues. The original 200,000 mile Delco fuel pump is probably on its last leg.

The engine is stock with the exception of Edelbrock TES headers, a 3" high flow cat, 3" single exhaust, and 1.6:1 roller rockers. Stock 3.23 gears.