I have a 1990 F-250 XLT Lariat, 5.8L, 4-wheel drive. It was running fine until i replaced the plug and wires. Now it is running real rough and has no power. I replaced the new wires with the old ones and nothing changed. Im going out of my mind. Anyone please help. could it be a bad plug? how would i check? thx in advance to any that might help.

 

Did you set the gaps correctly and did you run the wires like the directions told you too? Sometimes you can cross them or put them the wrong way and the engine won't run right. Make sure they are all tightly connected too with some dielectric grease.


Primary rig is Green Thunder:
95' F-150 XLT 4x4, 302, 5 spd, MSD 6A, Flowmaster American Thunder Exhaust, Sunroof, Clear corners w/ Diamond headlights, CD player with 2 10" subs and some 32" BFG Muds .

Check out my Gallery for a look-see.

Then theres:
99' Mustang GT 4.6L
88' F-250 Heavyduty 4x4 351/c6
95' Mercury Cougar 4.6L V-8
80' E-350 300/6 with a
3 spd column shifter. Weighs around 7,000lbs w. 65mph top speed, who wants to race me!

 

Make sure the firing order is still correct. Ituned up my 302 the first time and accidentally swapped two wires. Ran like crap until I figured it out.

Bill

 

Yes,
Make sure the firing order is correct.
The repair manual I had, had the wrong firing order for my truck, and it ran like #%*$.
The correct firing order was printed in the engine compartment near the radiator.
Once I got the right wires on the right plugs, it ran great again...
Best of luck,
Gene