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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: the_legend_1981 on July 08, 2011, 08:08:03 am

Title: carbon buildup...
Post by: the_legend_1981 on July 08, 2011, 08:08:03 am

Would dirty fuel cause carbon to build up on the spark plugs? The guy that had the truck before me ran bad fuel and I recently changed the plugs and a couple had some bad carbon buildup. The plugs looked really old too.

Title: Re: carbon buildup...
Post by: the_legend_1981 on July 08, 2011, 09:43:22 am

actually not even carbon. looks more like ash.

Title: Re: carbon buildup...
Post by: Captkaos on July 21, 2011, 04:09:30 pm

pics?

Title: Re: carbon buildup...
Post by: thachevythang on July 22, 2011, 03:24:26 am

When I pulled my engine, my plugs were in that exact same condition from the previous owner and the truck was running like crap. Spitting black tar out the back and smelled really rich! I had a blown head gasket and a bad header gasket. This was the condition I bought the truck in so figured just change gaskets. When I pulled my intake, it was completely clogged with solid carbon. There was only about a pencil eraser size hole on the largest port on one side! The heads had the springs too tight and no seals on them either. I'm not sure if this is what caused the build up, but after my top end rebuild they stay clean. I cleaned up the intake, re-used it, and have not had any issues since. I'm not a mechanic but that what my issue was. Maybe you just needed new plugs?