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97 Suburban no spark


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Join Date: Nov 2010
Posts: 8

November 28th, 2010, 6:35 PM   #1  
CF Beginner
97 Suburban no spark

Alright after a full bottom end rebuild and a whole lot of cursing I am that much closer to getting this thing to run. Its the 5.7l V8.

Here's where im at..

No spark at the spark plugs.
Have spark coming from the coil. Tested with old plug wire and new coil-cap wire..

I just get no spark from the cap, i ended up buying 2 caps, one from ebay and one from O Reilys. I have tried both and get no spark out of either of them.
I honestly have no idea what it could be...

Truck ran fine before this whole rebuild, we have been trying to get this thing to start up for a few days now with no luck. It started and ran badly once, but power steering leaked so after fixing that real quick it went back to not starting..


I am thinking that either the coil is going out and does not have enough power to get the spark to jump across the gap in the cap.. Or both the caps i have are just junk....

Im about to push this thing off a cliff..

 
Join Date: Nov 2008
Posts: 2,955
Bowie, MD

November 29th, 2010, 6:56 AM   #2  
Super Moderator
Professional Mechanic
Is the piece that the crank sensor reads installed back behind the timing cover?

 
Join Date: Nov 2010
Posts: 8

November 29th, 2010, 10:37 AM   #3  
CF Beginner
Yup. When we were assembling the motor we forgot to put it on, so we had to pull the pan and front cover back off to install it.

I am assuming that the Crank position and Cam positing are being read properly because the coil is giving spark.
The only things that i can imagine that would be wrong would be the coil or cap and rotor..

Is there a way to test that spark coming out of the coil? I remember doing a resistance check and one reading being slightly out of what AllData had said it should be. Maybe the secondary coil going out?

Is it even possible to have the cap turned that far out of time that the spark wouldnt jump to one of the posts? This just makes no sense to me.....

 
Join Date: Oct 2010
Posts: 14
New York

November 30th, 2010, 8:56 PM   #4  
CF Beginner
1. weak ignition coil.
2. low or no voltage to the primary (positive) side of the coil.
3. high resistance or open coil wire, or spark plug wire.
4. negative side of the coil not being pulsed by the ignition module.
5. defective pickup coil.
6. defective module.

 
Join Date: Jan 2010
Posts: 122
SC

December 1st, 2010, 11:10 AM   #5  
CF Active Member
Have you got a rotor installed in the distributor?

 
Join Date: Nov 2010
Posts: 8

December 2nd, 2010, 2:30 AM   #6  
CF Beginner
Yes there is a rotor installed. And the motor started up after we cleaned all the plugs off. But wouldn't start again once we killed it. And now when I test the plug wires with a spark test light I get nothing coming out from the cap.
Is there an easy way to check if it's the coil or pickup module that's the problem? I would guess it's the coil because if I use the online spark test light it lights up nice and bright right from the coil wire going to the distributor. I even put a plug up to it and got a nice blue spark. I have tried 2 kinds of plugs now. One set is AC delco platinums and the other are some triple platnums that schmucks said were the OE ones...

 
Join Date: Apr 2008
Posts: 7,230
Austin, Texas

December 2nd, 2010, 8:25 AM   #7  
Administrator
If I read your post right , it sounds like the breakdown is at the cap/rotor
make sure the contact button in the top of the cap that contacts the rotor is still in place and not broken,chipped or stuck in.

 
Join Date: Nov 2010
Posts: 8

December 2nd, 2010, 11:45 AM   #8  
CF Beginner
Ya, to me it seems like it would be the cap and rotor. But i have 2 brand new sets that i have tried and neither of them work.. I have check each set and everything looks perfectly fine. Thats why i was thinking that maybe it could be a weak spark that is not jumping across the points?

 
Join Date: Nov 2010
Posts: 8

December 3rd, 2010, 2:45 AM   #9  
CF Beginner
Turned out to be the crank sensor.. I was getting a very inconsistent spark from the cap after further inspection. Then tested the input to the ignitor and the ac voltage was bouncing everywhere. Changed it out and it started right up.
Now I just need to throw a timing light on it and see why it runs like crap. Have no power at all and misfires.

What tool do I need to set the computer timing. I'm getting a code that I can't remember right now that when I looked up said something along the lines of cam/crank position problem. Gunna get back at it tomorrow.
Thanks for all the help guys!!

 
Join Date: Nov 2008
Posts: 2,955
Bowie, MD

December 3rd, 2010, 7:06 AM   #10  
Super Moderator
Professional Mechanic
Can not use a timing light. You need a scan tool that shows live data.

 
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