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

Easiest way to check for fuel, and spark?

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Old 03-31-2010, 10:16 PM
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Default Easiest way to check for fuel, and spark?

Whats the easiest way? Car ran fine all the way home, stopped for gas, started up fine again, then went to start it up at home. On first crank it started for a mili-second and stalled as soon as I tried to move it. Now it just cranks.
Old 03-31-2010, 10:36 PM
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Fuel - using a fuel pressure gauge to check for ample pressure. About $30 from pretty much every parts store.

Spark - using a spark tester. It's basically a big spark plug which measures the strength of the spark. Use it directly off of the coil to check for spark going in to the opti.
Old 04-01-2010, 11:13 AM
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even easier way to check for spark, pull a plug and have a buddy stand with the plug tip grounded to the frame while you crank, if you see spark, you have spark. free.
Old 04-01-2010, 11:22 AM
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Originally Posted by bufmatmuslepants
even easier way to check for spark, pull a plug and have a buddy stand with the plug tip grounded to the frame while you crank, if you see spark, you have spark. free.
Well yeah, but you won't be able to tell if the spark is weak or not.
Old 04-01-2010, 11:45 AM
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or put your finger in the boot..........
Old 04-01-2010, 01:53 PM
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Got fuel. no spark. The icm tested fine, and I replaced the coil. Still doesnt start. Could this be anything other than the opti? I just replaced the opti 8 months and 3000 miles ago with a new delphi unit from thepartsladi.
Old 04-01-2010, 02:41 PM
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no codes
Old 04-01-2010, 03:34 PM
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You say 'no spark". Where are you checking? if your getting no spark out of the coil, then its your ICM, coil, or something in the wiring to the coil.

if you're saying no spark at the end of the plugs.. well, need to suspect bad plug wires or bad opti distributor... I'd check more than just one plug wire to be sure.

anybody - the optical sensor part of the opti serves as the trigger for the coil to spark, right? if I'm right on that, you need to include that and its wiring as well.
Old 04-01-2010, 05:21 PM
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I checked at the coil. ICM is fine, or so says the tester at autozone.
Old 04-01-2010, 07:12 PM
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Originally Posted by djjab57
or put your finger in the boot..........
I was gonna suggest to put the plug in your mouth and crank it...
Old 04-01-2010, 07:20 PM
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Originally Posted by hyperzone
anybody - the optical sensor part of the opti serves as the trigger for the coil to spark, right? if I'm right on that, you need to include that and its wiring as well.
Correct. http://shbox.com
Old 04-03-2010, 02:42 AM
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What about the crank position sensor?
Old 04-03-2010, 04:18 AM
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That will not cause a no start. It's there on obd 2 for emissions only
Old 04-03-2010, 05:32 AM
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Just FART when trying to start!! LOL
Old 04-05-2010, 01:22 AM
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^ I dont get the point of this post?

So its either the opti, or the wiring for the opti?
Old 04-05-2010, 09:01 PM
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Originally Posted by bore.me
Did you read my link? It explains how to check the wiring to the opti. It helped me fix my car when it used to stall. It turned out to be my opti.
Old 07-21-2013, 01:12 PM
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I know this is an old thread, but good info. Just ordered a spark tester, don't know why I hadn't heard of it before.



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