Hi, i have a firebird formula, 1991 5.0 with a 5 speed and on the hood it says LAC 5.0
I recently had to replace some things on the fuel system, seems a mechanic i had it towed to once for a fuel pump replacement didnt know what it was either since he put the lo pressure pump on it and butchered the harness in tank to make it fit, oh and also he is not around anymore to talk to about that.
After the pump got replaced it just didnt seem to have the power in the upper part of rpm range and i couldnt for the life of me figure out why and replaced practically everything on it before finally i needed another pump and found what the problem was all along.
So my question to be clear is when buying parts like fuel injectors what do i ask for.
Ones i have in it now leak badly and when i took them to the gm place they looked in a book to match numbers on top of it and there was a big section of numbers missing like for example the numbers went 10990,10991, 10992,11560. not actual numbers but mine was actually in the range not listed in their books, they didnt know what to give me so gave me what they thought it was and they just dont seem to perform as good as the ones that drip.

 

as long as there 19 pound injectors you should be fine.. they might had put larger injectors in, then you would be running too rich, and losing some performance. all 305's got 19pds, 350 got 22 i think.

 

correct your 305 got 19ib injectors make sure you dont have the 350's 22ib injectors or youll be getting too much fuel since your computer is tuned for the 19iber's

 

ok, so even tho this one takes the higher output fuel pump the injectors are same?
why it even needs a higher fuel pressure is confusing.
The problem i have is the new injectors i buy DO NOT perform aswell as old.
Old ones have alot more power in hi rpm's, only problem is they are abit dribbly instead of mist, ive cleaned them up fairly well and changed the screens and what not but i still had a dribble or two as it idled.
The car has no mods except the Jet Stage 2 kit.
Also What should i do about the harness in the tank being cut, im worried that a wire splice in tank could be trouble at a later day.

 

when it comes to fuel pumps and gas tanks, id say take it to a GOOD shop, have them check that. as for the injectors, if youre older ones are that great u can always send them in to get refurbished. theres a few places that do that, they can be found here by searching, or do a yahoo search..

 

If he can actually WATCH the injectors "dribble" a bit at idle, I'd have to say we're dealing with a TBI motor here, not TPI. If this is the case, I doubt the pump is causing pressure problems. That usually only occurs when a TBI pump is mistakenly put into a TPI car. If that shadetree mechanic put some Chinese junk pump in there, it could be causing problems. Stick with AC Delco or Walbro when replacing the fuel pump. A couple of tips on TBI injectors. For one thing, it's almost unheard of for them to actually go bad. My original TBI injectors have over 240K on them. Mine also appear to dribble somewhat at idle. It only turns into a fine looking mist when you open up the throttle, so this is probably normal. The only thing that ever went bad on mine so far was the o-rings that go on the top and bottom of the injectors. When that happened, they were literally dumping fuel at idle. After replacing the o-rings and screens, it's run beautiful ever since. The other tip is I'd be willing to bet the dealership gave you the wrong injectors to replace yours. The lack of power is probably due to the fact that they gave you something like the 4.3 V6 injectors instead of the correct ones. Even a lot of the businesses that are supposedly "experts" on the TBI systems get the injectors mixed up. If you read some of the posts on the TBI forum, you'll see how true this is. My advice would be to get a basic TBI rebuild kit that comes with new o-rings, screens, gaskets, and regulator diaphragm. Then put your original injectors back in with the rebuild kit. If your new injectors are a different color on the top compared to your originals, I'd almost guarantee they gave you the wrong ones. Make sure to lubricate the new o-rings with some ATF before installing them, otherwise they get cut easily. Chances are, this should fix your problems. If not, then it might be wise to get a good, quality replacement fuel pump since the mechanic more than likely put in some foreign, mickey mouse pump due to the fact they're a lot cheaper than the good ones.