Driving my C-10 home after work today (11 mile drive, mostly highway) and it started misfiring or stumbling going uphill on rhe highway. Going back down hills it was fine...for a while, then it started kind of misfiring in general. Limped it home and went inside to eat and chill for a bit. Went back out 2 hours later and took it for a test run. Ran fine for 5 minutes until I hit the first hill, started stumbling again until I leveled back out. Ran fine for several minutes on flat land and then started stumbling again regardless. It is a 283 with points and condenser. (old points and condenser, and coil) Could it be that the coil is failing and when it was still fairly cool only the load of going uphill bothered it until it warmed up and started failing even on flat land? I know it is either fuel or spark. Just wondering if anybody has seen a similar situation before I switch out the fuel pump and carb off of one of my spare engines.
I've been driving it every day for the last couple of months because my daughter took my other daily ride. It likes gas so I put at least a half tank in a few times a week.
Look at the coil. Run it in the dark and look for sparking. It sounds like your coil may be the suspect.
Before you change parts (better idea than the parts shotgun, so thumbs up), remove the fuel filter and blow through it. Check fuel pump output. Check dwell and timing. Pull one spark plug and look at condition and 'color'.
With a miss under load, most people first think it will be fuel. Most times it turns out to be an ignition problem. Start with points / coil.
Fill the fuel tank up until it will take no more. Drive the car up a hill. If that solves the issue, perhaps your fuel gauge is a little off, and you were approaching empty. Hills make the problem worse as the fuel slooshes away from the suction. If that doesn't solve it, check float level on the carburettors. Cheers, Harv
Okay, thanks for all your help. I have to work at 3am so I was away from the computer for a while to make a long shot in a scramble to get it figured out before I had to go to bed. (now) Anyway, it dawned on me that I had a spare coil in my hibernating Rambler wagon in the corner of the barn. All my other stuff is capacitance discharge. It didn't take long to switch out the coils. Took it on a shakedown run and, lo and behold, it ran crisper than it had in a long time. No more stumbling. I really felt like it was going to be fuel related but I got lucky on the first shot from the parts shotgun. Doesn't happen that way very often. Thanks again. This place is such a resource for everything.
After dark open the hood with the engine warm at idle and mist the cap, wires and coil LIGHTLY with a spray bottle of water. If the wires leak you will see it.
In hindsight, about a month ago I noticed the headlights and instrument cluster were very bright. Checked the battery with a multimeter and it was charging at close to 19v around 2k rpm. Put a one-wire alternator in it to bypass the apparently faulty voltage regulator. (fixed the problem) The super-charge session probably contributed to the slow death of the coil.....
Check the cap. I had a cap that was cracked between two posts. I think is was carboned up and trying to fire both at the same time.
People will keep posting with suggestions on what to fix, without reading that you fixed the issue. As payment for getting lucky with the parts shotgun, you have to try at least the first three to even out your debt Cheers, Harv
Happy to hear you found and fixed the problem. Many years back I had an early S-10 pickup that had the exact same issues as you described. It was the coil also.
I built a shed in my backyard. Local laws allow 10ft to the peak without a permit. I am a little over. My dad said not to worry about it, if a neighbor calls the town and it is determined to be too tall, rather than lower the roof you can simply raise the ground the shed is on. Point being ... the first solution to the problem that comes to mind (I built the shed too tall, I will now have to shorten it) may not be the only solution (pack 4 inches of dirt on the ground, directly below the peak). So easy How does this apply to your issue? Simple ... you are having a problem with hills causing a miss-fire. Rather than search for what you think is probably the most likely cause, you actually have the ability to change the rules of the game here ... it is as easy as moving to the prairies. No hills, no problem I get such a rush out of helping people In advance of your "thank you so much, I hadn't even considered that" I say to you "you sir, are very welcome"
Do take a look at plugs & wires too. Sometimes ignition coils die because another faulty part push up the voltage needed to make a spark (such as a worn spark plug with larger spark gap or a wire with an internal break the spark also has to jump), the increased voltage puts a bigger load on the insulation internal of the coil, eventually letting the spark punch a hole through and suddenly you have a coil unable to supply a high voltage - the spark will simply occur internal of the coil instead when it's easier to reach ground that way. Other times it finds other ways to ground that is easier than sparking on the plugs, such as carbon tracking in the distributor. Have you noticed that modern cars seem to eat ignition coils for breakfast? Same problem, but there it's a result of intentionally running the engines under conditions that demand a high voltage. The engines run lean to reduce emissions, lean mixes cause higher spark voltages (and are harder to ignite so you need a high energy spark). To increase chances if igniting that lean mix spark plugs have larger gaps, making longer sparks that again bump up the voltage. On top of that the engines run high compression to give descent economy, also bumping up the voltage required. No wonder the modern engines kill ignition coils all the time, alternately get the spark in the wrong location i.e. carbon tracking to ground somewhere externally. Unfortunately there's not much you can do to help the coil in these engines, apart from staying on top of maintenance, not letting plugs wear to too large gaps. That's a lot of words just to say that a bad coil (or other ignition part) sometimes is a symptom, not the cause.
Glad you found it. I found long ago that missing under load at lower speeds, especially when applying throttle to accelerate was almost always ignition. Wires, Plugs, point gap, condenser or coil..
I should probably put new wires on it. I cannot remember the last time I did but I've owned the truck since '92. Surely I replaced them once this century but can't swear to it.
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