TBI ? am i getting enough fuel? or not enough? PLEASE HELP! - Third Generation F-Body Message Boards

septsaf16 · 10-22-2009, 10:39 PM

I just swaped my 305 to a new crate 350, 305 HP out of the box im running a stock 305 throttle body w/ 454 injectors with all the goodys, headers, msd ign., eldelbrock preformer intake and a few other small mods. but im running a stock fuel pump, is it giving the injectors enough fuel? it pulls great to 3500 RPM then falls off and kinda boggs and pulls back and forth to 5000 when i shift "not as bad when its been running a while". I think its to rich by the smell at a idle, but from what ive read on hear I think I need to upgrade my fuel pump to a higher volume one. also my computer is stock I was thinking of upgrading it. If either which do you think I should do first? I have no clue about TBI's

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RBob · 10-23-2009, 01:04 PM

The BBC injectors without any tuning is an issue. If anything I recommend that you put some orange/black 350 injectors in. At least the tune will be closer to the actual fueling requirements.

As for the fuel pump, yes it may be running out of steam. The only way to know for sure is to put a fuel pressure gauge on the supply line to the TBI unit. Then go WOT and observe if the pressure falls off.

A quick check is to watch the gauge and just whack the throttle wide open (trans in neutral, car not moving). If the pressure drops even the slightest then there isn't enough fuel delivery. Note to only hold the throttle open for a moment, don't over-rev the engine. Just want to hit the throttle fast to create a demand for fuel.

But get some 350 injectors in there until you can start tuning.

RBob.