’99 F150 – Intake Gasket Replacement, Spark Plug Change, Injector Cleaning

I was getting a misfire on cylinders number 7 and 8. After some investigation I noticed the spark plug hole #7 and #8 was full of antifreeze. 🙁 Apparently the intake gasket was leaking and the spark plug holes were conveniently right there to catch the spill. The high voltage from the coil was shorting to ground through the antifreeze. So it was time for a new intake gasket. I also changed the spark plugs and cleaned the fuel injectors. I found a good way to clean injectors is attach the straw from your favorite carb cleaner to the input of the injector. Then spray the carb cleaner while applying 12v to the terminal of the injector. You may want to point the injector into a bucket or coffee can so you don’t blow carb cleaner all over the place. This is also a good time to watch how the carb cleaner exits the injector, it should be a uniform spray. I will attach a photo to show you the difference. Removing the intake was pretty uneventful. I did not realize the intake was a two piece unit until I remove the intake, that explains the other gasket. There is a plastic air reserve tank that hangs under the intake. But, the intake is aluminum, I know on some of these 5.4L Ford engines they are plastic. Reinstalling was a little more challenging, since I did not have an assistant I had to rig up a small ‘intake hoist’ to help me move the intake into place without messing up the gasket.

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