Boreen

Alright. I am so close to bein firing up my ls3 swap for the first time, and I am actually gettin excited. But I ran into a few problems tonight.
First. I have the aero motive fuel pressure regulator/lines that hawks offer, and a Walbro 255 pump in the stock tank. Now on my gauge (mounts on the regulator), when the pumps off, it holds 20psi. Soon as the pump runs, its at 55-60 psi. What should it be, and what should it hold when the pumps off?

Also, tonight I tried to fire it up, no go. Pulled a plug to check and have no spark. Now what could cause this? Plugs are like new (very few miles), new 10mm plug wires, coils are used (very few miles). Everything is also hooked up correctly. Didn't miss anything that I could find. Any ideas on where to start?

86gn

iTrader: (3)

Make sure you have power going to the coils and a signal from the crank sensor and also the VATS is turned off on the pcm and also I think a bypass on the 1991 factory vats system

Pocket

iTrader: (24)

Pump and regulator sound like they're working properly

3rd gen and LSx VATS are separate systems. If the engine spins over, the 3rd gen VATS is defeated or working properly. No fuel on the LSx, Id check the PCM for VATS

Boreen

That's good that the pump/regulator are working properly.
VATS is disabled on the car; I swapped in a carb'd 355 before this to replace the 305 TBI.
VATS should be disabled on the ECM already as its the GMPP LS376/525 controller kit that I am using.
We used this kit on our 65 impala that we also put a cammed ls3 into, that one fired up like nothing.

Wonder if my plugs or coils are bad?
Coils/plugs have 5000miles only. Wires are brand new 10mm aftermarkets.

What else could be causing no spark as well?

Now I'm not exactly sure how these injectors work. But they should spray when cranking correct? Because I cranked for maybe 10 seconds. Didn't fire at all. Pulled #1 plug and it was dry as well. So now I'm stumped.
Fuel is getting to the rail too btw.
I'm gonna double check all my wiring tomorrow now as well.

drduster

iTrader: (2)

My swap didn't start right away & took some troubleshooting too. I'd disabled VATS in the PCM using HP Tuners. I have the Hawks fuel lines/fuel pressure regulator too, & had fuel getting to the fuel rail. I used a spark tester tool to verify I had spark when cranking. Then went to Auto Zone & got a Noid Light Set & verified the injectors were getting pulses while cranking. With fuel, spark & injector pulse, it seemed like the only thing that could still be wrong was that the injectors were not spraying fuel. My engine sat for over 4 years since the last time it ran. I sent the injectors to a "rebuilder", Cody Motorsports in GA, because the cost was the same as one new injector from AC Delco, $107. He said 4 of them were not working at all, & 2 of them were leaking. He also said the ethanol in gas makes them get gummed up if they sit too long. I got a set off ebay from a guy who had just upgraded in his 2000 Camaro. With the fresh injectors it fired right up.

87CIZ

iTrader: (8)

how are you controlling the ls3? fbody harness and pcm? if so you need to change wiring on the camshaft position sensor and the crankshaft position sensor if i remember correctly. If those sensors arent in agreement, they wont allow any spark from the coil packs. It's been about 5 years since i did an ls3 swap, but i ran in to the same problem. I used katech harnesses to lengthen the original harness to the ls3 sensor positions. But i had to swap 2 wires on the crankshaft position sensor if i remember correctly.

Boreen

I am using a GMPP LS376/525 controller kit (found on Pace Performance).
Everything is plugged in correctly as well as far as I know.
It cranks and cranks but just won't actually fire as there is no spark anywhere.
Must be something in the controller kit I am assuming.

alan91z28

the gmpp harness, etc already has vats disabled, etc

do you have hptuners, efilive, etc that you can look at the computer and see what is going on? ie do you have any DTC (error codes being set, etc?)

also there aren't many connections to make to that harness, but have you double checked everything to make sure all your wires are connected properly? especially check your grounds for good connections between battery, chassis, engine block, and the harness

i used basically the same harness, in my thread i have some wiring diagrams on how i hooked it up around post 150 or so if i remember

Dustytrix

iTrader: (3)

I think it maybe a ground wire, I had one that acted just like that and it was a loose ground for the coils. They are 2 grounds feeding the coils and you need both.

Boreen

Figured out the issue. Normally there is a "jumper" wire for the cam sensor that basically swaps the position of two wires. Cut/soldered the wires where they should be and it fired up.
So close to bein done this swap finally.