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**usp55** · 08-18-2008, 05:33 PM

Re: Fuel options...

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I just ordered everything for my cam install last night(exact setup u are planning). If it comes in the mail by sat ill put it in the shop monday moring to get it all installed. I was planning on running it stock like funkz has done. He said it ran too rich on the 19lb injectors.

**nightrider2** · 08-18-2008, 06:30 PM

Re: Fuel options...

you need to use the 19lb injectors in conjunction with a 255 and AFPR. what happens with stockers is when you force them to over spray you get more of a jet and less of a mist. when you have the fuel like that you get an effect much like a carb that is too big, you mash the throttle and it will stumble, or just run sub par. by using larger injectors at a lower pressure you don't over work them and you keep that fine mist. you'll have better throttle response, keep better fuel mileage, and make more power. Fuel systems are tricky and its tough to get right...you could leave every thing be and it could run fine. but it won't run its best. If you going to do a cam...do up the fuel system to support it properly.

as far as who to take advice from (besides me :D ) talk to speeding firebird. Funkz talks a lot of ****, and has no idea what he's talking about.

**Blizzard242** · 08-18-2008, 06:34 PM

Re: Fuel options...

^^^x2:tup:

Fuel delivery is not something you want to half ***.

**nightrider2** · 08-18-2008, 06:35 PM

Re: Fuel options...

Originally posted by usp55 View Post

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I just ordered everything for my cam install last night(exact setup u are planning). If it comes in the mail by sat ill put it in the shop monday moring to get it all installed. I was planning on running it stock like funkz has done. He said it ran too rich on the 19lb injectors.

on 19lb injectors a cam only motor WILL run too rich. see my last post...A fully worked fuel system with an AFPR is the only way to guarantee a proper running engine. even on a stock tune especially on a stock tune.

**tkoforpresident** · 08-18-2008, 08:27 PM

Re: Fuel options...

okay night rider, so your saying go with the walhbro 255, holley AFPR, and stock 19lb injectors for the BEST setup?

and you say run low psi so what does that mean... 40?? 35??

why wouldn't i want to run high pressure?

btw thanks for the advice, its great to have someone who knows what they're talkin bout help me.

**jrocstar** · 08-18-2008, 08:36 PM

Re: Fuel options...

i would run stock and see what injector duty is at if it is over 80% at WOT then worry about it. if you modify anything else you jsut altered your fueling calculations and your ltft and stft will fight trying to correct the issue so when you go from part throttle to wot you might go lean or rich depending on the trims. that is not a huge cam just try the stock ones and see what happens but if you are indeed over the 80% duty cycle then yea nightrider is correct stock fuel pressure or maybe 5 psi less with bigger injectors and a larger pump will give you streetability and tuneability

**travis brackett** · 08-18-2008, 08:42 PM

Re: Fuel options...

Originally posted by tkoforpresident View Post

and you say run low psi so what does that mean... 40?? 35??
.

??? your current fuel pressure is ???

**tkoforpresident** · 08-18-2008, 09:59 PM

Re: Fuel options...

Originally posted by travis brackett View Post

??? your current fuel pressure is ???

well i'd have to look it up but i believe stock for the 3.4 is 35-45 but i could be wrong.

**tkoforpresident** · 08-18-2008, 10:02 PM

Re: Fuel options...

Originally posted by jrocstar View Post

i would run stock and see what injector duty is at if it is over 80% at WOT then worry about it. if you modify anything else you jsut altered your fueling calculations and your ltft and stft will fight trying to correct the issue so when you go from part throttle to wot you might go lean or rich depending on the trims. that is not a huge cam just try the stock ones and see what happens but if you are indeed over the 80% duty cycle then yea nightrider is correct stock fuel pressure or maybe 5 psi less with bigger injectors and a larger pump will give you streetability and tuneability

sorry but i don't want to take out my injectors twice, it's kind of a PITA with the 3.4 as they can't come out without taking off the intake manifold. I'd rather just get the 19lbers, AFPR , walbro 255 and call it a day.

i really don't mind bad mpg, i just don't want to run horribly rich all the time.

i do have some questions though...

1. how does having the bigger fuel pump help me out ?
2. how does lowering the fuel pressure help me out when i'm using bigger injectors?
3. how can you test to see what duty your injectors are running at?

**jrocstar** · 08-19-2008, 06:39 AM

Re: Fuel options...

you will need a scanner or some type of tuning software. the lower pressure helps keep the injectors from overspraying at idle which if you have that issue with that small of injectors god hates you. you will be altering your fueling calculations which can cause tuning issues just be warned. the larger fuel pump makes sure the fuel is there to back the pulse width of the injector without large pressure drops

**tkoforpresident** · 08-19-2008, 07:26 AM

Re: Fuel options...

Originally posted by jrocstar View Post

you will need a scanner or some type of tuning software. the lower pressure helps keep the injectors from overspraying at idle which if you have that issue with that small of injectors god hates you. you will be altering your fueling calculations which can cause tuning issues just be warned. the larger fuel pump makes sure the fuel is there to back the pulse width of the injector without large pressure drops

so it all helps eachother out in the end, giving me more fuel in a better spray pattern, when i need it, not at idle. saving me mpg, giving me more power, and a smoother throttle transition??

sounds good to me :tup:

btw, i have NO options for tuning, which is why i'm in this dillema.

**nightrider2** · 08-19-2008, 04:13 PM

Re: Fuel options...

you have to take the valve covers off to do a cam so the injectors will be easy to access...and you run lower PSI to limit the amount going through the injectors to keep from running too rich...I have 24s in mine ;)

**tkoforpresident** · 08-19-2008, 05:22 PM

Re: Fuel options...

Originally posted by nightrider2 View Post

you have to take the valve covers off to do a cam so the injectors will be easy to access...and you run lower PSI to limit the amount going through the injectors to keep from running too rich...I have 24s in mine ;)

i know the valve covers have to come off, i've taken apart my top end before, i'm just trying not to have to do it TWICE because my injectors aren't big enough.

now that thats settled and i will be going with the 19lbers, 255 walhbro and the holley AFPR, can someone tell me if the stock 3.8 injectors fit my 3.4??

i imagine some used ones would be cheaper and more available.

this is gonna sound kinda random but what would i need to do to remove my crankshaft pulley? it's an automatic and haynes says to stick a screwdriver in the gear teeth through a hole in the tranny but i've yet to see such a hole.

can it simply come off by putting the car in park with the emergency brake on and breaking the bolt that way?

thanks for the great help

max

**nightrider2** · 08-19-2008, 06:25 PM

Re: Fuel options...

..........you hurt my brain....just put a big ****ing breaker bar on it and hit it with your palm...ans far as 3.8 injectors yea that'll do...I ran them with a stock pump and stock FPR...ran a little right but it picked up in the top end

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