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My first attempt at resolving this issue involved me getting my 80lb injectors pressure cleaned and flow tested by WitchHunter Performance. He found one of them was bad and I've since replaced it after having him test the new one.
I would hate to have to tear apart the engine so I'm trying to do any diagnostics before going that route.
I didn't actually get a chance to check the fuel pump this last weekend so this weekend should be the big weekend!.....
3/30/2017:
In the meantime, looks like I'm also getting a new fuel pump. I bought my fuel pump from Quantum Fuel Systems in 2010 and they have good customer service... as you can see:
-------- Original Message --------
Subject: Re: 255/190 pump 1991 Pontiac Firebird (Inquiry #77851)
From: <Napster134>
Date: Wed, March 29, 2017 5:51 pm
To: Quantum Fuel <sales@highflowfuel.com>
On Tue, Mar 28, 2017 at 9:22 PM, <Napster134> wrote:
Hi there,
I bought this fuel pump from you locally a few years ago.
Recently, my car started acting up and the latest suspect in my troubleshooting is the fuel pump or the fuel pump strainer.
I was curious if you would be able to test my fuel pump or if there is any way I could test it myself?
Here is thread on the issue I've been experiencing with my car.
Hope you could help me out.
This is the big weekend! Last weekend, found the tank was dirty so washed it with soap and water and got all the dirt out! Having to wait for it to dry out in the sun caused the new delay... almost there!...
Backfiring out the intake side = lean mixture, ignition timing errors including plug-wire crossfire, exhaust valve not opening/restricted exhaust, or intake valve not sealing.
Backfiring out the exhaust side = rich mixture, exhaust valve not sealing.
Backfiring out of both intake and exhaust only at heavy throttle, and it used to run good? I'd be performing a cranking compression test, a leakdown test, and a cylinder-balance test on all eight. I'd be suspicious of valve problems. (although the jumping tach needle may be pointing to ignition misfire--hard to tell from the video.)
Backfiring out the intake side = lean mixture, ignition timing errors including plug-wire crossfire, exhaust valve not opening/restricted exhaust, or intake valve not sealing.
Backfiring out the exhaust side = rich mixture, exhaust valve not sealing.
Backfiring out of both intake and exhaust only at heavy throttle, and it used to run good? I'd be performing a cranking compression test, a leakdown test, and a cylinder-balance test on all eight. I'd be suspicious of valve problems. (although the jumping tach needle may be pointing to ignition misfire--hard to tell from the video.)
My dad also mentioned valves. If this new fuel pump makes no difference then that may be our next route. I have replaced the plugs and wires already and no difference. A few years ago, I also replaced the ICM inside the distributor, however, that was to troubleshoot a different issue which I found the ICM/Distributor was not actually the cause of the issue.
I could try a new distributor and see if that makes any difference before I start tearing apart the engine. I would hope the fuel pump does the trick! ... I'll update on the status of that in a bit.
Napster, I have a question for you. What procedure did you use to set the fuel pressure? And what regulator do you have?
As I mentioned here; I have an Aeromotive 13301 Fuel Pressure Regulator set at 24PSI. It's also vacuum reference.
Procedure:
1) Pop the hood & disconnect vacuum line to regulator.
2) Stand by driver door w/ Driver Window rolled down and Key Off Engine Off
3) Place hand on key then turn to ON (KOEO - i.e. No cranking)
4) Quickly move my body around the mirror and into the engine compartment
5) Take note of the fuel pressure.
6) Adjust pressure screw in to increase or out to decrease.
7) Repeat steps 2-7 until the desired pressure is noted in step 5.
Last edited by Napster134; Apr 13, 2017 at 12:14 AM.
Reason: corrected FP to actual FP ATM
So I just ran all your specs through Dyno2000, while I know its not the most accurate software, I'm confused as to why you are running such low fuel pressure. With the superchager you have me beat on HP and I"m up at 26psi. So I'm not sure why you are so low. I'm guessing 500hp+ with your setup. 36psi in the EBL_utility software = 503hp. So by my calc you are way low with your fuel pressure.
So I just ran all your specs through Dyno2000, while I know its not the most accurate software, I'm confused as to why you are running such low fuel pressure. With the superchager you have me beat on HP and I"m up at 26psi. So I'm not sure why you are so low. I'm guessing 500hp+ with your setup. 36psi in the EBL_utility software = 503hp. So by my calc you are way low with your fuel pressure.
18psi only gets you 356hp.
Opps! That part of the thread is no longer valid. As you can see, the thread was created when I started setting up the supercharger. Since then pressure has been bumped to 24 PSI and well my FPR supports the 1:1 rise when boost is seen. I copied and pasted and missed fixing it.
Also, Rocket-Doc... I just noticed you ran my setup through some simulator. That sounds kinda cool. Can you post it? Anyhow, one more thing to mention...
My injectors are the 80lb injectors. Are you also running those?
24psi only supports 411hp though. Still a bit low IMO. Then again my boost knowledge isn't the greatest. I'd still increase it and see what happens.
Well as I mentioned, this setup did work just fine before. And increasing the FP was something I did actually try... The same problem was occurring even at really high pressures... (high as in 28-30)
The supercharger isn't set right but you are still higher than me.
36psi is needed for 503 in this.
Wow, that's pretty cool! Well, hopefully one day I'll get to see what the real numbers are! Still needs a good tune but it runs good when it's working the way it should...
Bad news guys ... new fuel pump in and still the same issue... if anyone else has any suggestions please let me know. I believe the compression test is next...
So! I finally fixed this problem... And here's a "FIXED!" story that is typically non-existent at the end of all the other forums I found when researching a solution to my issue...
If you'd like to cut to the chase then please read the bold text as those three sections are basically where the problems were.
Here's what happened:
I continued to drive the car periodically on the weekends when I had access to it.
My cousin also suspected fuel so we hooked up his fuel pressure gauge with a long line and mounted it to the windshield. Took it for a ride and hit the gas. Fuel pressure rose as it should since it's vacuum referenced. From here on out, I was not convinced that fuel was the problem. I strongly started to suspect a flat cam lobe... sadly...
So... I parked the car and left it alone for a week. I found out about a car show my work was hosting so I thought I'd bring my car even if all I could do was rev it up a bit... so I asked my dad if he could clean up the engine bay until I got home this last weekend to pickup my car.
As soon as I arrived my dad greeted me with "You're car's not starting!" so we pulled a plug and found no spark existed!
I then noticed that the two wire connector coming from the inside of the car to the coil was frayed and only connected with literally two single strands of wire on the coil side. Just to be safe, I purchased both coil connectors (black and grey) and soldered them back in. Plugged everything back in and still no spark!
Kept troubleshooting the rest of the day and then! ... My dad took off the distributor cap and noticed that the spring-loaded carbon button that touches the rotor had popped off and was basically crumbling to pieces. Replaced the distributor cap. Still no spark!
Finally, in a desperate attempt to troubleshoot quickly, I replaced the entire distributor. Still no spark!
With less than a day left, I asked in a separate thread about my issue. RBob responded and from his information, I was lead to the two wire connector between the coil and distributor (which I had already soldered a new coil end connector to). I replaced it and THEN found that the original had the terminals (on the distributor side) pulled out just enough to make it not too noticeable and just enough to make sure I had no contact between the coil/distributor.. Once replaced, I had spark! ...
I set the timing, took the car for a ride and hit the gas. For the first time in over 2+ years my car took off without any popping or chugging!
The power is not all there (from where it use to be) but my throttle body popping has been fixed and my car has regained most of it's power back.
... new fuel pump in and still the same issue... if anyone else has any suggestions please let me know. I believe the compression test is next... 
