Need advice--1987 F-150/302. Passenger side plugs stop firing. Plugs, wires, distributor replaced. After engine has heated,the 4 cylinders on
passenger side stop firing. I can check plugs and 4 seem to be wet
with raw gas. It's unpredictable when this problem may start. Sometimes
can drive 30-40 miles without it missing a beat, yet other times I can drive
2-3 miles and this problem starts again with the missing and skipping. It
seems that it happens after engine has heated up. btw, all drivers side plugs look and fire normally. And of course mpg is cut in half when this occurs.
Thanks for suggestions.

 

Coil. Would be my guess

 

I would check the wires, cap and rotor. Be sure none of the plug wires are arcing across themselves and the rotor and cap are not scored and cracked.

 

this truck is a really picky truck if 2 wires on the cap are next to each other they need to be routed differently one on the bottom of the wire loom and one on the top so they dont cross fire against each other lets say cylinder 1 &4 are next to eachother on the cap run 1 on the bottom & 4 on the top so that when their turn is over so to speak they cant ark against each other eliminating the fire completely

 

Thanks for the suggestions. As soon as time permits I will get back to trying your
helpful ideas. It's been a work in progress.
rosce jr