Recently did a tune-up, normal stuff really; wires, plugs, points, cap and rotor. I also checked the timing, did an oil change and popped the carb top to see if there was anything "really" bad floating around in the bowl, and finally adjusted my idle screws a bit. After the tune-up it ran like a champ, idle smoothed out and the power was good.

So, I jumped on I-25 South bound headed out to Rox's place to make a delivery and about 10min into the drive on the freeway at around 70-75 mph it started acting like it was running out of gas, quick look at the gauge and the aux tank was on empty, no biggie since the main was full, switched it over and NOTHING changed, still acted like it was starving. I was able to limp it off the freeway and into a gas station. Popped the hood and looked for obvious signs of problems, nothing, it would idle rough but it wouldn't sustain high rpms without gurgling. Dropped the hood and limped home at about 30mph, coughing with no power to grab the truck so I could make the delivery.

Today I was able to pull it in the garage and around, swapped out the fuel filter since it acted like it was starving, no change. So i checked all the previous tune-up items and everything was good except the no.1 plug pictured below. The tip is loaded, metal by the looks of it when I took a file to it and the cylinder was wet with unused fuel.

I always start my trouble shooting to the last thing that changed, so that is why I started checking the tune-up items. What do you guys think is the cause?

Any chance you forgot to gap it? Or maybe whacked that tip on it as you were installing it in to the head?

Spit balling here. Were you able to check the gap before you took the file to it?

Checked and re-gapped all the plugs (new in box), and I'm a straight shooter on the holes. There was no gap left on the picture above, took a file to it because it wouldn't just wipe off or scrape off. Thanks and keep the ideas coming.

So that electrode is pretty much fused to that tip huh?

Temp range too hot?

Stock heat range, all the other plugs looked good, I'll pull the numbers off the plugs to confirm there wasn't a mix up somewhere. BTW - the plugs had only a couple of hours on them.

I'm stumped on the plug too. On another note, 7 good cylinders and it should be runnin' better than you described. I wonder if something may be stuck in the fuel line further up from the filter. Can you put gas into the spare tank and switch back to it? It could be the fuel pump. A real reach would be the supposition that you sucked some rust and maybe some 1970's leaded fuel crap into the cylinder and when firing it melted and stuck to the plug tip. More likely, it's a little too advanced and the additional timing is causing heat and problems. Did you give it another 1 or two degrees when you tuned it?

I wonder if you didn't blow a chunk of carbon off the piston or combustion chamber during your high speed romp. That stuff is pretty hard.

Mitche11 -
Unfortunately I agree with you on the 7 cylinders, I recently had the experience when I lost a plug wire and it felt boggy but didn't feel like this, so I'll dig into the fuel system a bit more. I have a backup fuel pump I'll put in and I run a couple of filters inline for the very reason you mention (old tanks and previous junk stirred up into the fuel system), so I'll swap in a new filter in the 2nd filter location.

I didn't adjust the timing, but I'll back it off a bit to see what happens, I'm running 10 degrees right now so I'll back it down to 6-8 degrees.

Booger -
It's a possibility, I do run rich up in the mountains all the time so some carbon could have built up. I cleaned up the the plug and re-gapped it, I'll be able to run it around this afternoon when I get off work and give you guys some feedback.

Thanks for the suggestions, I'm a bit hazy on what the next step will be if none of the above makes a difference.

My first guess would be a plug wire. If you still have the old wires, swap one of the old wires out for that one new wire and see where that gets you. The quality of new wires is horrendous, as I have had to replace new wires before that ever made it on the vehicle. I've seen where both ends are loose inside the boot or one end is loose and the connection is never made. It could be that no or little spark is getting into the cylinder from the coil through that particular wire and intermittent spark is causing just enough ignition to gum it up and foul the plug like that.

Thanks sbolt, that was something I was thinking as well, again going back to what changed recently with the tune up. I tossed the old wires, one had come apart on me, hence the tune up. I'll pull a spare out, but I think I'll also send the new wires packing and pick up a replacement set.

Checked the wires with an ohm meter, seem good at 20'ish for the couple I checked (incl the no. 1 cylinder), I also pulled the valve cover just to make sure all was normal. I fired it up and went around the block and it ran fine, pulled it back in the garage and pulled the no. 1 plug and it looked fine, checked the points and they are good at 28 degrees and backed the timing off a bit to 8 degrees. Just drove it to my son's soccer practice and all seems normal, of course I'm hyper aware now. So who knows what happened, I've loaded up my diagnostic tools and I'll carry them with me for a few days. I'll let you guys know if it acts up again.

Big thanks for all the suggestions!

Good luck!
P.S. Great profile pic!