Question about 1991 Ford Mustang

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What would cause 2 of my spark plugs to melt the electrode off ? both on the same side #3 and #7 on a 1991 5.0 thats in my 1996 f150

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Were they the same brand of plug wires?

Posted on Apr 08, 2011

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  • lentzer69 Apr 08, 2011

    yes all the wires are the same 8mm. i was wrong on the order tho its #5 and #7 the plugs were autolite double platinum gaped at .44,was only in for 1wk last night i put motorcraft plugs in. it runs good for now but the autolites also did for 3-4 days. i just dont want to tear anything up if there is something i can fix to make sure it dont happen again. thanks for your in put,this is my only means of transportation to make it to work.

  • lentzer69 Apr 08, 2011

    I also put new wires on last night.I dont know too much about these newer 5.0 motors all the sensors and ****,this is the first truck ive owend that had all that stuff. Ive always had 74,77,78,79 ford f150's. So now 2wks ago i decided to try my luck with a 96 and now this and to top it all off when i ran the block numbers it comes back as a 91,but thats how my luck runs.

  • Charles Huckeba
    Charles Huckeba Apr 08, 2011

    Running platinum plugs is your first mistake. That engine was not designed to run platinum plugs. Run a copper core, preferably motorcraft. The platinum plugs are designed to burn hotter, and while that may seem like a good thing, it has different applications. The plugs burn hotter and that is what causes the electrode to burn.



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Generally in a spark plug is 60000 kilometers, if fuel is bad need in early, remove the spark plug, such as for auburn or rust color, spark plug showed normal; Such as stained with oil, shows that the spark plug gap imbalance or too much oil, high tension line short circuit or open circuit; Such as black smoke, spark plug type cold wrong or mixture is thick, the oil is up; Such as the top between the electrode and sediment, when for the oily sediment, shows that the cylinder into the oil has nothing to do with the spark plug, when the black sediment, spark plug carbon deposition and bypass, when grey sediments, is a gasoline additive covered electrode lead to lack of fire; If serious erosion, such as the scar at the top, with black pattern, electrode melt, showed that the spark plug is damaged.
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Inspect the electrodes and ceramic insulator.

  • Burned or worn electrodes may be caused by:

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There are many types of spark plugs available for your engine. You didn't state what year your F150 was made so I guessed about 2006. The plugs should be the same for a couple of years either side of that, but check to make sure when you buy them. Prices range from $2 each to $9 each. I have had success in my pickup and in my car with Bosch Platinum +2 plugs, which cost about $5 each. They require no gapping, and the platinum electrodes last a long time. They have a five-year warranty. They're available at most auto parts such as Advance or AutoZone. Other manufacturers make compatible plugs -- Champion, Autolite, Motorcraft, and AC Delco.

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