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1986 F150 302 EFI Answered

.wont idle correctly, under throttle it skips, loses power like it's starving for fuel.  I've replaced, idler air control motor, ignition coil, cap and rotor, fuel tank, high volume fuel pump, plugs and wires and fuel pressure regulator.  Could it be the distributor itself or does anyone have a solution?



6 years ago

The head gasket might be leaking your compression out so there is not enough to spark an ignition.

Get a compression gauge and check each cylinder and see what the readings are. It could be valves but those are usually specific to a cylinder and produce a pattern of missing. If you have only one reading that is low it could be valves. If its more than one its probably the head gasket although that more often causes problems with the compression escaping into the water jacket. And of course the other possibility is a broken ring or several rings. Those will allow the compression to leak into the crankcase and it just dissipates although you could get a smell of gasoline in the oil. If the compression readings are low then its going somewhere. Head gaskets aren't to hard to replace. Rings are harder and you might need to have the engine pulled to do it depending on how its set up. On many engines you can remove the oil pan and get enough space to take the connecting rod bolts out so you can remove the pistons and change the rings.