LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

no spark or fuel, what gives

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Old Jan 3, 2009 | 11:54 AM
  #1  
camzaro28's Avatar
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no spark or fuel, what gives

EDIT: go to post #20, didnt want to start another thread. But your more then welcome to read it all


My car has been broke down for months now, and havent had much time to get it running. Its at a friends house and I need to get it out of there, and in dire need of help.

The car has no spark at all, and the only sign of fuel is, I can hear the pump prime.
I guess for now, if I could get sugestions on the few things that would cause my problems so I can try and narrow it down.
Thanks in advance

Last edited by camzaro28; Feb 15, 2009 at 11:09 AM.
Old Jan 3, 2009 | 02:12 PM
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where in fl are you. there is ALOT of things it could be
Old Jan 3, 2009 | 02:57 PM
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car is in Palm Coast.
VATS? while doing a search that seemed like a possibility. How would I narrow that down?
FYI, car ran fine. Then drove it to gas station, turned it off, and it would not start again.
Old Jan 3, 2009 | 03:16 PM
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one way for bypassing VATS is to ohm the resistance in your key. then splice in the same resistor in the ign switch to fool it into thinking the "chip" is engaged. i've done it to cadillacs but never to an LT1 car. is it your only ignition key? have you done any work to the car recently?
Old Jan 7, 2009 | 11:56 PM
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besides the IAC and TPS, no. the car wouldnt hold an idle so I replaced those adn that problem was fixed.
Yeah I am going to try that or just replace the lock cylinder. I only have one key.
anything else I should look into?
Old Jan 8, 2009 | 06:41 AM
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It't not the VATS unless your security light is on.

The opti must be in working order for you to get spark and fuel.
Old Jan 8, 2009 | 07:31 AM
  #7  
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the security light flashes a couple times once the the key is in and trying to start the car, but does not stay on.
I bought a opti from Cromer and installed it, no difference. This would be my 3rd opti, so I think I installed it correctly. BUT, if I pulled the opti off ( still everything connected otherwise ) and manually turned it ( acting if I were the cam dowel ) the noid lights ( I have noid light on injector ) would light up and the car would actually try and start. So that got me thinking the opti was not sitting on right, but then I put a piece of gum in the hole to make sure the dowel was going in, it was enough to spin the rotor. So I concluded that the opti is fine
Even though the opti is what I messed with, being I did it manually, still cant rule anything else out.

So shoebox, what I understood from what you said, the opti is possibly the reason I am not seeing fuel? hhmmm, anything I can do from here to determine wether or not the opti is the problem?

Last edited by camzaro28; Jan 8, 2009 at 07:36 AM.
Old Jan 8, 2009 | 11:58 AM
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Seems like you tested the opti and it was ok. If your noid lights are blinking, then the PCM is allowing the injectors to pulse. Is your fuel pressure good?
Old Jan 8, 2009 | 12:09 PM
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over 40, IIRC.
Before it broke down ( when I was having issues with keeping an idle ) the lowest I seen it at was 38.
It has the walbro 255.

About the noid light, while cranking it does not blink. Sometimes it wil be really faint, but overall there is no blinking light.
The only way I got the noid lights to blink was to, pull the opti off and twist it by hand with everythign hooked up.
Old Jan 8, 2009 | 12:10 PM
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Also while cranking I lifted the fuel rails up and no fuel was coming out.
Old Jan 8, 2009 | 12:27 PM
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from the injectors or the rail?

maybe a faulty pcm?
Old Jan 8, 2009 | 12:30 PM
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I pulled the injectors up along with the rail and while cranking no fuel came out the injectors.
I was thinking that, but from what shbox just said about the noid light blinking that the PCM is sending the signal. So I am assuming the PCM is good.
Old Jan 8, 2009 | 02:55 PM
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Not to make things sound to simple, but if you are not getting a spark, have you tried a new coil. I think they are only about $20. I'm assuming it cranks, just doesn't start.
Old Jan 8, 2009 | 04:58 PM
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I put a new coil and ICM on there. Along with new Opti.
TPS, IAC, COIL, ICM, OPTI are all new.

There is no sign of spark anywhere in the ignition system. I used a DMV and went over all the wires and from what I checked they all seemed fine.

One thing I just remembered, while moving stuff around in the engine bay, I kept hearing this clicking noise. Ended up being the optu connector harness on the passenger side near the intake manifold. IIRC it didnt matter if I had the key in the ignition or not. Does that sound normal, possibly a clue to my problem?
Old Jan 8, 2009 | 08:19 PM
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If you have not checked the opti harness you should. Something is going on, if you get pulses when the opti is unmounted and not if it is. The harness may be going open when you move it around.



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