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1996 GMC Sierra 5.7L Ignition Problem


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pblanton
New User

Mar 17, 2015, 6:04 PM

Post #1 of 3 (5005 views)
1996 GMC Sierra 5.7L Ignition Problem Sign In

I have a 1996 GMC Sierra Z71 with 5.7L Vortec V8. It had a bad intake manifold gasket.

I carefully took it apart down to the block, cleaned it thoroughly and replaced the gaskets. Then I carefully reassembled it, reconnected the wiring harness connections, flushed the oil and coolant and refilled it all.

The engine turns over but won't fire. I can smell gasoline coming out of the exhaust so I feel like the fuel system and throttle body is working right.

I thought that the distributor may be out of alignment, so I carefully removed the distributor cap and loosened the distributor so that I could move the rotor. I rotated it about 180 degrees until it set back into the oil pump slot and reassembled it. This time when I tried to start it, it coughed fire and sparks out the air intake and I could smell burned gasoline. It smelled like proper exhaust... so I assumed that the rotor was now exactly 180 degrees out of alignment, so I repeated the procedure to move the rotor back to the other position.

I checked the spark coming out of the coil, just before it goes into the distributor and it is fine.

It still wouldn't turn over. As a sanity check and a troubleshooting step to rule out the fuel system, I sprayed starting fluid into the throttle body throat and tried again. but still no joy.

I presume that my timing is off enough to prevent it from starting, but the Vortec engines don't have adjustable timing like a non-computer controlled engine does. I did take a picture of the distributor before removing it and have re-positioned it in exactly the same position, so it shouldn't be off enough to cause a starting problem.

Any tips on how to fix the timing, or if it even a timing issue? My Haynes manual shows instructions for setting timing on older models, and I've done that plenty, but the Vortec is different. How do I go about setting it back to top-dead-center and getting the rotor lined up with the engine?

Or is that not the problem?

Thanks!


Discretesignals
Ultimate Carjunky / Moderator
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Mar 17, 2015, 6:18 PM

Post #2 of 3 (5000 views)
Re: 1996 GMC Sierra 5.7L Ignition Problem Sign In

 






Since we volunteer our time and knowledge, we ask for you to please follow up when a problem is resolved.


pblanton
New User

Mar 18, 2015, 9:18 AM

Post #3 of 3 (4986 views)
Re: 1996 GMC Sierra 5.7L Ignition Problem Sign In

Great information! Thanks!






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