There is no way its priming for even close to 5 seconds. I would more like 2. Maybe that can be another reason as well.


When i get home from work im going to unplug the o2 sensors and give it a go.

I didn't realize it was a video, lol. Mine does exactly the same thing, though I didn't think it was supposed to bleed off that fast. I don't know. I have to let mine fully prime before I try to crank, or it won't start right away, I have to crank it for a few seconds, 4-5 or so. If I let it prime for ~3 seconds before I start it will start in under 1 second

Yeah, it only primed for a second or so. That's a parameter in the ECM, just change it

Kirk said the same thing about it bleeding off fast. In my XJ jeep i had to leave the key on for 3-5 seconds so it would prime and then it would fire right up. I cant to that with this bc the pressure drops so damn fast.

Bleeding off is common in aftermarket fuel pumps because the check valve sucks

Did some more trouble shooting yesterday, here’s what I learned.

1. Fuel pressure does bleed off quick, but it maintains 55-60psi while cranking

Result: crank, no signs of firing

2. Unplugged the o2 sensors, since the only time it really ran was with no 02s

Result: crank, no signs of firing

3. Checked all plug wires, everything looked good

Result: crank, backfire/pop threw intake with some smoke out of the lid.


Tonight I’m going to pull the spark plugs and check em out. Praying it’s not a timing issue. Don’t know how it would be possible since it was lined up perfect, but who knows.

By "no signs of firing" does this include having no spark?

Yeah, did you check for spark and fuel? Is the harness an original f-body harness?

What I mean by that is it doesn’t even sound like it wants to fire.

It’s gettig fuel at the rail atleast. And I would assume it’s getting spark by the backfire.

Yes, original LS1/4l60e fbody harness

I'd check to make sure each cylinder has spark

This is what I was getting at, you should verify fuel and spark to all cylinders since it seems like something hokey is going on

Well you don't have an opti to fail and it's nearly impossible to cross your plug wires (not sure about coil harness, maybe verify that). You're positive the crank and cam are lined up right? New or used timing chain? No sensors left unplugged? Chase (the3lite) had issues keeping it running, iirc the cps was unplugged.

Cant cross coil harness, they run along the injectors and would only work one way due to the IAC and TPS being on 1 side.

Cam and crank were aligned, I dont think if they were off it would even have fired in the first place no?

I will rego over sensors today.

You can be a tooth off and it will run albeit poorly and noticeable. How long did it run? Just once, backfire, die within a few seconds?

Ran for prob a combine 10 seconds. Started it up the first time and it fired right up. Started it again a few minutes later to get a vid, started right up. Didnt shut off on its own either time. Killed it bc gauge cluster was not hooked up, so couldn't see if it had oil pressure and didnt want to risk it.

I'd crack the throttle a little and see if it changes/tries a little. I'd also hold it WOT and see if it tries to fire since that should disable injectors if you have a flood condition. Also, losing your primed fuel pressure is not good/not factory/should be fixed/probably bad fuel pump check valve/hey cool switches captain!

Possible? Yes. Recommended? Hell ****ing no! :rofl:

Spent about 6 hours on the car after work trying to get somewhere, and i think i just went backwards.

My friends, some of you may know him as well, Nishan came over with HP tuners to try to get this party started.

https://farm5.staticflickr.com/4480/...2657f279_z.jpg

After messing around for a while and not getting anything more than a 1 second fire up and die we pulled the plugs.

Cyl 2

https://farm5.staticflickr.com/4509/...e5df0624_z.jpg

Cyl 4

https://farm5.staticflickr.com/4445/...d87f1509_z.jpg

Cyl 6

https://farm5.staticflickr.com/4466/...20625583_z.jpg

cyl 8

https://farm5.staticflickr.com/4468/...d773867d_z.jpg

Cyl 7

https://farm5.staticflickr.com/4494/...bbb4c60a_z.jpg

Cyl 5

https://farm5.staticflickr.com/4496/...66c2df3e_z.jpg

Cyl 3

https://farm5.staticflickr.com/4474/...a0a79ac6_z.jpg

Cyl 1

https://farm5.staticflickr.com/4509/...2a148a24_z.jpg

As you can see, not good lmao I also verified spark at on every plug using a new plug from extra set i had.

Unplug coils 1 and 5 and see if anything changes? Verify fuel injectors are receiving signal and are pulsing fuel? Neither smells like fuel, correct? Check compression and check valve train operation and timing of events.

Did you verify injectors are firing on those cylinders?

Injectors are getting signal, didnt pull any to check. Nish actually texted me today to see if i had a set of stockers laying around to swap and see if it would fix it.


In addition to the spark plug catastrophy, once of the few times the car fired up it reved to the sky. As it started to go to the sky we killed it. Looking at HP tuners showed the throttle was 100% open. A quick look at the tb rocker and cable verified that it was witchcraft, so we tried to start it again. Same ****. Pulled the MAF and stuff to see the blade of the TB stuck wide open. niceeee. Literally just touched the tb cable to start to take it off and the TB rocker and return spring just fell off in my hand. Turns out the set screw that hold the rocker to the flat spot on the blade bar backed itself off some how. Pulled the TB off and fixed that. Threw it back on to the same results.

Just for ****s and giggles, kill the power for a little to reset the learned tables in the pcm. I doubt it will have an effect, but I don't like the wot issue. It almost makes me wonder if an injector or two are leaking down, hence your loss of prime pressure and your random backfire. As I said before, wot while cranking disables the injectors to help aid in clearing a flood condition. Just a thought....give 1 and 5 extra attention if you check this. Could explain the clean plug, could be something else.

We did clear out the PCM and start over, didnt make a diff. And what WOT issue you speaking of? Were it revved to the moon as soon as it started? I fixed issue. It was the TB.

Grabbing a set of stock injectors tonight from Mike just to see if thatll solve it. Hopefully itll fire with stock injectors

If you floor it while cranking, the PCM pulls fueling to clear a rich condition AFAIK.

replacement set of injectors aquired. Going in after work today. Hopefully thats the issue.

So is it fixed?