89 ford 300 4x4 4spd truck will start but runs rough backfires badd and smelling gas fumes ive searched for vacumm and exhaust not sure about the 300 inline six all my other fords are 302's so im new to this motor emission control and throttle body intake.. any help !lost....

 

I would check the timing, did this just occur or has it progressively gotten worse? Also I would check the codes.

 

Pull the dist cap and look for carbon tracks between the contacts in the cap. Look at the wires for cross firing, look at the plug wires at night in the dark with the engine running and see if you can see any arc's between the wires or to anywhere. If in doubt replace the cap and rotor and wires , can't hurt, if they are old.

stractor

 

Maybe the plug leads are on the wrong plugs. Easy to mix up if you pull them all of at once

 

I had a similar problem with my 300 I6. Check the timing, and if it is off, remove the distributor and check the gear. Mine had sheared the pin holding the gear to the distributor shaft. Gear had rotated significantly, but the pin had stayed in place, held by a small burr, holding the gear to the shaft.

Of course, about the time I had ALMOST removed the distributor, the gear fell off and down into the pan....where it remains to this day.

 

might check your intake gasket. I had two ports missing part of the gasket. ran like a piece of sh--, know runs perfect.

 

yes the distributor cap was very burnt and the wires were counter clockwise instead of ckw. i replaced the cap&rotor relocated the plug wires and its running strong now. im use to looking for the worse first but these 300"s motors i here are pretty strong.thanks alot guys..