I haven't done my swap yet so im with my stock 305 still. I'm Still prepping everything for my 355 swap coming in this month.I installed a fuel pressure (Aeromotive 13301)regulator and a 255 pump in my car and made myself a lil block off plate for the stock regulator in my car.

The regulator is located at the front of the engine, on the drivers side, where the rubber lines are going into the regulator. (Return at the bottom of reg. and Main line in and out the side the regulator to the TBI), So the steel return line is not being used.

My problem is: I bought some 350 (I think) truck injectors from a junk yard to be able to run my engine when I do the 350 swap. Now im really confused. The injectors have a weird little ticking noise here and there which after reading around I heard it is normal.

I have adjusted my pressure all over the place. from 13 psi to 24 psi. Ive been messing with my computer's BCP vs Vac settings and I'm completely lost, the problem is at WOT, sometimes the injectors die out and shoot gas every other half second and my car goes nowhere and sometimes they shoot a perfect stream and my car launches steady.

I though I had fixed the problem yesterday when I had my setup at 24psi, and 83 Vac n BPC... it worked until i actually drove around town it started screwing up again although i also did notice my pressure dropped to about 19 psi but when i raised it back up it still was shooting gas terribly when i floored it, the car will barley go. Could it be these injectors are bad? My regulator is too far from the TB? I'm setting the wrong BPC n Vac settings for the injectors? my brand new fuel pump is bad?

My best guess is bad injectors.

Thanks any help! I want to use the 7.4 TBI with my swap yet im confused on why this is happening now.

 

Well yes they could be bad, what #'s exactly are these injectors?

It sounds like there is an EBL involved, but it can't fix stupi...well you know. That pressure regulator needs no vacuum reference @ the pressure you should be using.

I take it you didn't have the injectors cleaned & flow tested?
Why not?? They are from out the junkyard!! Would be time & money well spent.

How in the world do you expect larger injectors to make your stock 305 run better?? It WILL run bad unless you lower fuel pressure, BPC & VE tables. What a waste of time!!

I hope you did not make the mistake of putting them in a 2" tbi & putting that on your stock 305 cuz that makes even less sense, if possible. Your 355 will have to spin about 7000rpm to use that thing & the 305 'bout 8000.

Help us help you & tell us what is going on. I would like to help, really, but let's not try to fix what does not, should not, or cannot be/need fixed.

If you are just experimenting, nobody hates you for it, it's good practice for stuff you have to learn by doing it yourself. Just get on with it & put the right parts back on when you get done playing around, don't waste your time here. Sounds like your just a little over excited to start playing with some of your goodies.

I'm much nicer then I sound in this post...honest. lol

 

You want your 305 to run better & have an EBL? You wanna learn? Do this, ya put the right injectors back in.

Add a little fuel pressure, try 14. Do VE learns, if it is adding fuel add a little more pressure.
It will quit adding fuel at some point, remember the EBL runs the fuel quite tight it's ok for it to show -2 or -3. When you get there, start to add timing 1000-2.5K, watch for knock counts, try to get as much early timing as you can & do VE learns between timing adjustments, leave the total timing alone. Just try to pick up the early points.

 

The problem is I dont know what injector # they are, thats why ive been messsing with the pressure and vac settings so much, I was going to go back to the junk yard and run the VIN of the truck to make sure they are 350 injectors. And no the regulator is not vacuum referenced yet.

I got the injectors for 5$ from a buddys junkyard so I thought id give them a shot. I dont expect it too run better yet neither did I expect them to run this bad.

My first guess was that the pressure would have to be lower due to the injectors being bigger, but I noticed they actually ran better with a higher pressue. So that brings me to think I will have to adjust the VAC n BPC settings at a lower pressue. The only thing that is not stock is the injector pod and the regulator.

And yes, I am just playing around and trrying to learn how to mess with all of this EBL stuff.

I stripped my 305 injector pod inlet which is why I havnt been able to go back yet, but the swap is comming in soon so I dont care much bout them going back in.

 

I never thought the BPC and vac settings made much of a differnece untill yesterday went i went from 120 to 80 for the new pressure of about 22psi and thats when it finnally topped out my first gear with no sputter. I left it alone. When I drove it around later that afternoon, after about 15 minutes it started sputtering again even at 1/2 throttle.

 

So i did what you said, xch3no2. I have the same problem. I dont think the injectors had anything to do with it. My 305 injectors are doing the same thing. Now I have been thinking and i have limited this down to either: 1. my brand new fuel pump has went bad already or 2. my new pressure regulator setup isnt right.

I hope and really think it has to do with the regulator setup. Could it be that my regulator is too far from the injectors that its not holding pressure. I can rev my engine as high as I want as long as its gradual. Once I hit the gas about half throttle or full it sputters constantly, and my car wont go anywhere.

Its drivable as long as I stay under 2500rpms

Any advise?

 

One more thing, when I rev the engine by hand while watching my gauge, if the rev is gradual my pressure will stay steady and at 12-13 psi. Once i hammer it, it drops to 0 psi.

I never knew you could swap the injectors between pod, I just found out because I was looking at my old injector pod and noticed the o ring so i swapped the old injectors back into my new pod.

 

Ohhh damn!
I'm glad I stopped by, yes you are having a pump/supply problem of some sort.

Do a pre-regulator pressure and volume test to verify pump.

There has to be something gone awry!

Aftermarket regulator on supply side of injectors can fall down, that won't happen on return side where it belongs.
I hope that's all it is.

I might ask what pump went in but that is likely irrelevant.

Fuel being in the tank, pump being secure, pickup clear, hose from pump to delivery line intact/unrestricted, filter flowing freely, those things matter.

Watch for bubbles in fuel during volume test.

 

Ok i am going to follow the tests in this article tomorrow: http://www.aa1car.com/library/fuel_pump_diagnose.htm

Also I drew up this lil diagram of what my current setup is and attached it here. After looking at the pictures on that site I see that the regulator is after the injectors.

This is what my current setup is:

I installed a 255 pump

TBIsetup-1.jpg?t=1289014755

Thanks for all the help.

 

that's a really rough draw lol

 

No sweat I understand.

Fuel must go from the pump to injector pod inlet,

Through injector cavity to pod outlet, THEN to the regulator inlet with regulator return to tank.

IOW on the other, or return side, of the injectors-to maintain constant, steady pressure on the injectors.

Don't worry, the regulator will release extra pressure to the the fuel tank.
But very importantly NOT before the injectors.

I think we found your problem.

edit: I just looked at your test schematic, notice where the regulator is located.
.

 

Yea it appears plumbed wrong. Reg needs to be in return line. distance not a big deal. mine is about 12 inches down stream from TB unit in return line.

 

Thanks for all the help. I can see why it wont work out with my original setup. I will be starting the swap on Thursday so I wont bother to move it to the return line till then since my stock tb return outlet is stripped and plugged. I hope I can handle staying under 3k rpms for 2 more days lol.

I have my reg. a bit farther than 12". Its near the charcoal vac canister by the alternator.

Ill update once the new engine is up and running.

Thanks again.

 

So I have my car up and running with the new engine. Its to bad I have a new problem .

I started a new post since I seem to be having a different type of problem so maybe I can get some more help with my new problem.

Heres the update:

https://www.thirdgen.org/forums/tech...ml#post4747152

Thanks for all the help.