LT1-LT4 Modifications 1993-97 Gen II Small Block V8

Fuel Pulse question

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Old Oct 19, 2010 | 10:30 PM
  #1  
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Default Fuel Pulse question

What creates power to the injectors ?
I have finally got spark
and now im having a issue getting fuel.
I have a brand new fuel pump, 42lbs svo

im checking out the fuel filter and any clogged fuel line. Also checking out the fuel pressure regulator too.

My main issue is tho im not getting fuel pulse.

New Opti, New Coil, New ICM.

Also, i recently did a rebuild to this car just cant seem to get it all there.

any suggestions ?
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Old Oct 20, 2010 | 06:44 AM
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Check to make sure the injector fuses are still good. There are two of them, both 7.5A, in the underhood fuse compartment.

If the fuses check out okay, use a noid light to see if the PCM is commanding them to fire.

You should also check to make sure you don't have any stored codes in the PCM. A DTC 16 indicates a loss of the low resolution pulse from the optispark and will cause the PCM to not fire the injectors.

Also, is your security light on? A fault in the theft deterrent module/relay will cause the PCM to disable the injectors.
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Old Oct 20, 2010 | 08:30 AM
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Originally Posted by RamAir95TA
Check to make sure the injector fuses are still good. There are two of them, both 7.5A, in the underhood fuse compartment.

If the fuses check out okay, use a noid light to see if the PCM is commanding them to fire.

You should also check to make sure you don't have any stored codes in the PCM. A DTC 16 indicates a loss of the low resolution pulse from the optispark and will cause the PCM to not fire the injectors.

Also, is your security light on? A fault in the theft deterrent module/relay will cause the PCM to disable the injectors.
Ill check out all of of those today.
I dont have a security light on, just when the key is on but not running which is normal.

as for the DTC 16, even if i fixed the problem and the code is still on. It will not fire ?

If i use the noid light and the computer is not talking to the injectors what do i do ?
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Old Oct 20, 2010 | 08:48 AM
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Originally Posted by Next level
Ill check out all of of those today.
I dont have a security light on, just when the key is on but not running which is normal.

as for the DTC 16, even if i fixed the problem and the code is still on. It will not fire ?

If i use the noid light and the computer is not talking to the injectors what do i do ?
Right. DTC 16 shows the loss of the low resolution signal to the optispark. Without the signal, the injectors won't fire.

If the injectors still don't fire (confirming you have good fuses and no codes are present) then you're going to be doing some wire hunting.
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Old Oct 20, 2010 | 08:57 AM
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How have you made the determination that you're injectors are not getting pulsed?
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Old Oct 20, 2010 | 11:13 AM
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Originally Posted by garage_queen
How have you made the determination that you're injectors are not getting pulsed?
I took the noid put it where the injector hooks up to and tried to start the car, got nothing.

I checked the Fuses good
DTC was clear, no codes
theft module is fine

any other ideas ?

would pressure have anything to do why its not pulsing ?
ie. fuel filter, clogged line
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Old Oct 20, 2010 | 11:17 AM
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Do you have 12v at the pink wire of each injector?

If you are positive the PCM is not pulsing the ground to fire each injector, you need to check on the low resolution pulse of the opti. Scan for codes while cranking.

Fuel pressure will not affect the injector pulse.
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Old Oct 20, 2010 | 12:28 PM
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Originally Posted by RamAir95TA
If you are positive the PCM is not pulsing the ground to fire each injector, you need to check on the low resolution pulse of the opti. Scan for codes while cranking.
There arent any codes showing up, it would change if i crank it ?

ill check the 12v and other things around 2 and keep everyone updated. i really appericate the help guys!
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Old Oct 20, 2010 | 01:45 PM
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Originally Posted by RamAir95TA
If you are positive the PCM is not pulsing the ground to fire each injector, you need to check on the low resolution pulse of the opti. Scan for codes while cranking.
95ta you hit right on the head. We regrounded the PCM and I have pulse. Waiting on a fuel filter should be here in 10 -15 mins and car SHOULD fire.

thanks again and will keep everyone updated on the status. Should know by 4:00 PM
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Old Oct 20, 2010 | 02:49 PM
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Originally Posted by Next level
95ta you hit right on the head. We regrounded the PCM and I have pulse. Waiting on a fuel filter should be here in 10 -15 mins and car SHOULD fire.

thanks again and will keep everyone updated on the status. Should know by 4:00 PM
Your avatar is seriously distracting for those of us trying to think about tech. *Insert motorboat joke here*
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Old Oct 21, 2010 | 09:29 AM
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Originally Posted by ChandlerMotorsports
Your avatar is seriously distracting for those of us trying to think about tech. *Insert motorboat joke here*
I agree, I couldn't help but stare at them while I was trying to read the thread, lol! Very nice rack for sure.... Glad you found out your issue!
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