Seeking advice on 89 302 5.0


Junior Member
Looking at 89 F-150 4x4. Runs rough. Anyone have any serious problems with this year and engine? Truck in great shape, but not looking to put a whole lot into it beside tune-up and fluid changes. And/or what to look out for or check on this year and model.

not real sure about the 89 but i just got rid of a 95 f150 with the 5.0 my best suggestion is check the underbody real good, the body on mine was holding up real good but everything underneath was rotting away....brake lines fuel tanks and oh yeah that famous ford 5.0 oil pan was going fast far as the 5.0 mine always ran like a scalded dog this one might just need a tune many miles are on it?

good luck,
Check for vacum leaks also, especially between the upper intake and the intake manifold, gasket tends to suck in. Aside from tune-up, you might have to put it on a scanner to check electronics, especially if the old spark plugs are really black (rich) or whitish (lean) Could be bad MAP sensor or MAF sensor.
Hope this helps and good luck, Jason

Winterworks Veteran
Also look for low oil pressure at idle indicating worn mains. I have had 4 of these trucks and saw a problem with water getting into the oil. There has been discussion on this problem in the past here with various theories. One being condensation. In any event it was a problem.
Be careful if it's running rough.Ford had a major problem with ignition crossfire with the 5.0L truck motors.It will damage the piston,and eventually cause a meltdown.I had this happen personally in my 89 Ford van.BEFORE buying,have a compression test done,on at least #7 and #8.Another way to tell is use a boroscope,which allows you to look inside the cylinder (7 & 8) to see if there is any signs of crossfiring or detonation damage.Most good shops should have this piece of equipment.Ford has a TSB on this subject,just don't have the number handy

The #7 and #8 spark plug wires should not be run parallel to each other.Run the wire for #7 with all the others (down over the center of the rocker cover),and run #8 along side the upper plenum,behind the coil and over the back of the rocker cover.

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