Ok, I'd like to ask for ideas on what to look for to get this beauty on the road. First, in case my signature doesn't show, here are my mods:

383 ci, Lunati 243/251 .597/.603, Comp Ultra-Magnum 1.6 RR, 30# Bosch 3s @60psi, head and edelbrock intake port, 2.02/1.6 valves, 11.8:1 CR, full MSD ignition system, MSD wires, 58mm TB, Hooker LT headers, x-pipe with no cats with flowmasters, custom tune, 3600 stall, ProBuilt A4, 3.07 rear, many more.

This is a fresh 383 LT1 with a fresh ProBuilt A4. I got it to start one time, and ran it for about 10 seconds, before I let go of the gas, and it shut off. But aside from that, I can't get it to start anymore. It turns over, but will not fire. I thought it may have have been a grounding issue since braided ground wire for the block was split in half , so I went out and grounded it with a 4 gauge insulated cable, so that should take care of it. Nope. Still not starting. I've checked all connections and they are all good. TPS voltage is 0.71. The cap and rotor were recently replaced with MSD units, and I seriously doubt the opti is bad, since it was working fine when I tore it down a few months back. But I won't rule that out.

The machine shop built the bottom end so I would hope they had the timing right, but who knows. And I'm 99.9% sure the opti was installed correctly. Are there any checks I can perform, before I go and tear my front cover off?

 

are the injectors powering up?
ck the plugs see if they are wet

 

Hope you can get it up and running soon. Here is the first thing I would check,

A) is there fuel pressure at the fuel rail?

B) is there spark at the plugs?

C) you said it was tuned, was that's dyno tune or a mail order tune?

 

I agree. Start with the plugs. If they are dry, you're getting no gas. If wet, no spark.

 

are you using the stock computer with a new chip ?
have you checked for fault codes ?
the reason i ask is that i had the same thing happen when i tried to start up my 383 - showed a code 51 - incorrectly installed prom, turns out one of the small tangs had bent when pushing the chip in, fixed that and it started,
always pays to go for the fault code first.

 

Agree with the fuel pressure/plug check. I remember when I installed a new cam, 24lb injectors and Holley adjustable fuel pressure regulator on my L98, it was VERY sensitive to the fuel pressure.

 

There are many issues you could have. First see if it's a no spark or no fuel situation, that helps narrow it down. Fuel pressure is really big for these engines so if you are getting spark it should be something with either pump or regulator. Good luck

 

Yep^. This is pretty basic stuff here.

WHAT'S MISSING? FUEL OR SPARK?

 

I need to take a couple days off from the Vette. I'll check back in in a couple days. But as of now there are no codes. The tune is mail order. There is 60 psi at the rails but I haven't checked the injectors individually yet. Thanks for the responses guys

 

Tuesday Update:
This morning I had buddy mechanic come over and take a look at it. It seems if you floor the throttle while cranking it'll start right up. I still need to break out tunercat and see if it's an IAC issue, but good news is it's starting.

 

That is a symptom of a flooded engine. Check for leaking injector(s).

 

Flooring the throttle while crankkng shuts off the injectors. I had the same issue on a warm engine after installkng Bosch III injectors. At least for me the B3's were different to tune than other injectors I had worked with. You may need a different tune. Do you have the tools to tune? I might be able to help you out.

 

I do have the tools to tune, but I am using Solomon at lt1pcmtuning.com. I'll ask him about the Bosch 3s. What is the difference? Pulse width? It is on the first tune, and it definitely needs a retune. I'll be sure to keep this thread updated as I find things out. Thanks.

 

Full throttle while cranking induces the "clear flood mode" in the ECM,
Is your fuel pressure at 60 psi ? Try backing it off to 40 psi and try it again if you have an adjustable reg fitted.

 

Two weeks ago, I was able to get the car running for a bit. I drove it for around 50 miles (enough to break in the tranny). Then one night, I drove 1/4 mile, and the car just backfires like crazy, and will no longer start.

Upon examination, a couple of my spark plugs had begun backing themselves out. They were previously torqued to the FSM's spec of 11 ft/lb. I guess with all the mods, it's just bouncing around too much. So I tightened them down further, hoping that would fix the issue, but it still wouldn't start.

I suspected a leaking injector, so I sent them back to FIC, and one was in fact leaking. I ended up getting new 34# Bosch 3s rated at 43.5 psi. So I pulled the pressure back to 43.5, but the car still won't start. It'll put a bit when you play with the throttle, but it won't actually start. I pulled the valve covers, and everything looks tight in there. I'm just getting stumped. Is there something I can use to measure spark at the plugs? I have tried pulling one and grounding the side, and there is spark, but I'm not sure it is enough. I'm afraid at this point I'm gonna toast my battery or my starter from attempting to start it so much

 

There is some gismo for checking the spark. I kinda just go by the color. If it's orange I suspect it. If it's blue it should be ok.

 

You don't need any special gizmos. All you need is something that can provide a gap. It is harder for electricity to jump a gap under pressure (compression), so if you have a marginal spark in atmosphere, it's possible that it wouldn't jump the gap under compression.

To confirm, take anything that provides a gap. I use an old/extra spark plug. Plug one of your plug wires on to it. Now, Ground THAT device to the the tip of the plug that is still threaded into the respective cylinder, from which you used for the plug wire.

If a spark jumps the gap in your external spark plug, then in HAS to be also jumping the gap inside the chamber, under compression. That is proof that you have spark, and it is sufficient to start the engine.

 

I don't think it's fuel. I have 43.5 at the rails with brand new injectors. Granted the pressure does drop off after the fuel pump finishes priming priming (no noticeable leaks whatsoever).

My guess is that it's spark, just wanting to figure out where to start. I found the tips on shbox and plan to do those, but do you think something could have happened when the plugs were backing out?

 

Sorry, I just updated my post to be more aligned with the whole thread (including my own post!) No nothing happened when the plugs were backing out. If it didn't rip the threads out of the head, then everything is fine, w/regard to loose plugs.


Ah HA!



See my post immediately above this one...

 

I have a msd on my 90 it also would not start. I found that you need 12v+ from your keyed source or the ignition will not turn on.