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Old 03-07-2011, 06:52 PM   #1
Sinistrad
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Default LT1 no start. Cranks, has Fuel pressure, seeing spark. Thoughts?

Cranks, never fires.

Fuel pressure seems to test fine, 45-ish lbs when cranking/FP running, 35-ish when powered off and remains steady.

Pulled one spark plug to watch it spark and it sparks at fairly even intervals, but it was wet when pulled (so it doesn't seem to be burning the fuel)

K&N Air filter recently (today) cleaned and oiled.

No codes that I think are relevant - bunch of transient stuff that's been around for years...CCM: 51, 72, 74 ECM: 32, 72 ABS/ASR: 62 (this 62 is new, but I was stressing ASR recently and don't expect it to come back))

Any thoughts/suggestions about what to do next are appreciated.


Background: Car broke after a long day autocrossing - hit the gas, died. Started cranking with no start, but would fire every now and then, enough that I was able to get home, but seemed like it wanted to stall whenever I gave it more than the tiniest bit of throttle. Once home, won't start again. I cleaned air filter (needed it anyway), replaced fuel filter and pump/screen (pressure wasn't staying when tested, which the replacement fixed - so it needed it anyway).
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Old 03-07-2011, 07:37 PM   #2
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Since you have fuel pressure--I'd check injector pulse with a noid light next--I'm guessing you will since plugs were wet, but be sure. If you have pulse remove the coil wire from the opti and check spark ,while someone cranks engine. Spark should be steady/rapid--blue/white in color and jump 3/8 of a inch or so to ground easily. Since I've seen many issues with optis (most recently after the car had been hard) that would have been my first guess. I'd try these tests first before jumping on the opti though.
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Old 03-07-2011, 08:12 PM   #3
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Quote:
Originally Posted by TWISTERUP View Post
Since you have fuel pressure--I'd check injector pulse with a noid light next--I'm guessing you will since plugs were wet, but be sure. If you have pulse remove the coil wire from the opti and check spark ,while someone cranks engine. Spark should be steady/rapid--blue/white in color and jump 3/8 of a inch or so to ground easily. Since I've seen many issues with optis (most recently after the car had been hard) that would have been my first guess. I'd try these tests first before jumping on the opti though.
Thanks,

It very well could be the opti - water pump failure a month ago made for lots of wetness down there. That said, I thought opti failures meant no spark at all and likely codes?

Coil sounds easy enough, but I don't have noid lights for the injectors. No time to work on it until tomorrow night. I'll keep this thread updated with any progress.
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Old 03-07-2011, 08:28 PM   #4
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Quote:
Originally Posted by Sinistrad View Post
Thanks,

It very well could be the opti - water pump failure a month ago made for lots of wetness down there. That said, I thought opti failures meant no spark at all and likely codes?

Coil sounds easy enough, but I don't have noid lights for the injectors. No time to work on it until tomorrow night. I'll keep this thread updated with any progress.
More often then not when the opti fails it throws either a high or low resolution code, but not always-- i've seen them fail w/no codes.
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Old 03-07-2011, 08:48 PM   #5
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http://www.mainstreamtopics.com/foru...rt-diagnostic/
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Old 03-07-2011, 10:13 PM   #6
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Buy a cheap spark tester a any auto parts store and check your spark that way. Some times you can see a week spark and think its good but not have enough to run the engine. The tool is adjustable to test anything from a lawn mower to a new car for spark. They only cost like $5 to $10.
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Old 03-07-2011, 10:39 PM   #7
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if you have spark , and fuel, pull all your plugs, dry them and while youre at it check compression and take your air cleaner loose. reinstall the plugs if you have compression, spin it . it should fire. you may have other issues that keep it from running , but with those components , any engine will fire. kind of an oddball suggestion, check and see if you actually have fuel and not a water, etc...mix

Last edited by oldalaskaman; 03-07-2011 at 11:09 PM.
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Old 03-07-2011, 11:21 PM   #8
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this is an excellent link, many thanks, respectfully, bob
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Old 03-07-2011, 11:43 PM   #9
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Spark plugs are not supposed to be wet! Fuel pressure should hold up for at least 1/2 hr ign off. If it won't you may have leaky injector/s which cause so rich a miture, the engine will not start. Also, bringing a grounded wire close to the unplugged coil wire out of the opti should show a snappy at least 1/2" spark during cranking and the same from an unplugged spark plug wire. If you have a weak spark at a spark plug wire, the opti is likely defective. You might also try starting fluid and if the engine starts and quits, you have a fuel delivery problem.

Last edited by jfb; 03-07-2011 at 11:55 PM.
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Old 03-08-2011, 10:42 AM   #10
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I had same problem once, fuel and spark but the "fuel" was water, got a quart of water from a local gas station, pulled the fuel filter and when the "fuel" ran out it didn't smell. I looked in the gas tank and you could see the water on the bottom of the tank. You can also rent a set of noid lights at an auto parts store. good luck.
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Old 03-20-2011, 08:27 PM   #11
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Opti. Ended up taking to my mechanic Noid lights showed intermittent pulses. Runs better now than it has in years. 180k miles on what I believe to be the original. Here's hoping for 180k more.
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Old 03-20-2011, 08:27 PM
 
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