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The Grail
New User
May 16, 2007, 8:14 AM
Post #1 of 8
(7289 views)
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1999 Tahoe won't start
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I just found this site and there's a lot of good info here! Thanks in advance for your help. I'll try to make this brief.
In trying to make this 1999 5.7L run better, I sprayed Seafoam Deep Creep into the throttle body while running (per directions). You can see the black build up in the throttle body and I thought this may be why it's not running like it used to. Well, it stalled, and I can't get it started again. I don't have a fuel gauge, but I think fuel is ok. Tried starter fluid and still won't start. There is no spark to the several plugs I checked, either with the plug grounded or with a screwdriver. In running down the basics, I found the cap and rotor need to be replaced (lots of carbon/corrosion), and the plugs were soiled black. I will replace them but for now (before I go to the strore) I cleaned all and put back. I pulled coil wire off dist. cap and it would not spark when close to ground. How can I test this coil? The terminals are plug in connectors - I don't know which is negative or positive. What else can I check that would prevent the coil from sending spark?
I should have checked these basics first, before using Deep Creep. Could the Deep Creep have made it worse or is it just a coincidence?
One other thing that may be an indicator is that recently when you accelerate from a stop, it will slowly pick up speed, but you can feel it bog down. You can't pull out if anyone is near as it is very slow to get going. However, above 40mph or so, it is responsive and jumps when you punch it.
Thanks.
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The Grail
New User
May 18, 2007, 7:12 AM
Post #2 of 8
(7268 views)
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Re: 1999 Tahoe won't start
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Is anyone out there?
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
May 18, 2007, 8:18 AM
Post #3 of 8
(7266 views)
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Re: 1999 Tahoe won't start
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Yes - we are watching. I can't think of the connection between the deep creep solvent and the problems you are having so had nothing to add. Hope someone can - I just don't know what to say,
T
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The Grail
New User
May 18, 2007, 9:16 AM
Post #4 of 8
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Re: 1999 Tahoe won't start
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Thanks, Tom. I appreciate your input. Trying to figure out what, if anything, the solvent had to do with it has been frustrating.
From my online research, it seems the most likely failed components for no spark at the coil are the coil, the ignition module, or the crankshaft position sensor. I've read a few articles/posts that say the coil can fail because of bad plugs, wires, or distributor cap. The logic is that if the coil has to overcome these problems, over time it will fail. I'm thinking now that since the cap, rotor, and all plugs were fouled, the coil may have been struggling for some time. Using the solvent fouled the plugs even more and may have pushed the coil over the edge.
I guess I'll replace the coil, and if that doesn't work, I'll replace the ignition module. I hate to just swap parts, but these two items cost less than to tow it to a shop and have them troubleshoot it.
If anyone has experience with a 5.7L no spark situation, please let me know how it was resolved.
Thanks.
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Tom Greenleaf
Ultimate Carjunky
/ Moderator
May 18, 2007, 11:55 AM
Post #5 of 8
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Re: 1999 Tahoe won't start
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Some thoughts about this if it helps:
The coil can be tested with an ohm meter and damn if I can't recall the exact way and reading you should get. It's something like between neg or pos teminals and the spark tower should read X. It's probably a pricey part now and just tossing stuff stinks as a repair method.
What bugs me is the solvent in air horn and electrical anything that could stop it from producing spark. Extra load from cap, rotor, wires and plugs could strain things but if just the plugs got fouled they would take the current and spark would seek ground more easily and I would think the coil would be less stressed as it doesn't care if it's spark makes the vehicle run or not but just seeks ground. Does the coil have any 12V power to it? That and does it blink a test light? Those would be clues to the problem.
Coincidence could be at play here. You know -- you change the oil and now a power window doesn't work -- no corrolation.
It's probably best to chase down the ignition system and forget about the solvent being the cause right now.
If I think of anything to test or try I'll hit back. Do give a progress report and hope you find something simple.
By any chance did any wiring get disturbed in even getting to a point where you could use the Deep Creep. Silly things like that have come in for me to figure out ----an example: Customer just had checked the transmission fluid and now the car doesn't run?? Well don't I stumble on wires that got disconnected because they were in the way to do that or other times wiring gets moved and burns on hot exhaust parts -- just examples of that craziness.
Good luck and keep at it,
T
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steve01832
Veteran
May 19, 2007, 1:29 AM
Post #6 of 8
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Re: 1999 Tahoe won't start
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The next thing to check would be injector pulse. You can buy the noid lights pretty cheap. If you have no spark and no injector pulse, you could have either a faulty crank sensor or a faulty ignition module. If you have no spark but the injector pulse is ok, try a new ignition module. Also, check the fuel pressure. Off the top of my head I believe it is around 37 psi.
Steve
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The Grail
New User
May 19, 2007, 11:43 AM
Post #7 of 8
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Re: 1999 Tahoe won't start
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SUCCESS!!! It was the ignition module, $73 at Advanced Auto. It took a lot longer to go to the store and buy it than it took to swap it out. I plugged it in and it fired up on the first try.
Thanks for your input Tom and Steve. It must have been a coincidence with the Deep Creep, but I'm not going to try that anytime soon, just in case.
TO wrap things up, I was getting gas, as my new plugs were wet with gas. There was power to the coil and power from the coil to the distributor (to the rear plug-in, not the high voltage wire.)
Now, back to working on my boat...
Speaking of that, if anyone is looking for help with boats or boat motors, www.iboats.com has great discussion forums to help with all kinds of boating issues.
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sbake58
Novice
May 27, 2007, 5:50 PM
Post #8 of 8
(7239 views)
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Re: 1999 Tahoe won't start
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I've seen cases where turning the engine over with the distributor unpluged caused damage to the ignition module. Also the distributor gear is much softer metal than the camshaft gear, so excess wear can occur. This is noted at about 100K. Does not affect presence of spark unless completely worn off, but can affect smoothness and accuracy of distributor operation.
Good luck!
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