Mystery solved??
A couple weeks back my Bronco would not start. It would fire, cough and try to catch, but it was firing rough - to the point I thought the timing chain jumped.
Through trying to get it started and then diagnose, the battery got low. I put it on the charger and walked away without a solution (timing, compression, fuel, spark - all OK).
It has always fired right up cold with one pedal pump.
Next day, it fired right up and I drove it for a couple days - no issues. The battery was almost 8 years old and since it fired right up after charging it, I decided the battery had a cell was bad or something worst internally. Bought a new battery and been fine since.
Off on a week long camp/trout fishing trip with the Bronco. Rained and rained and rained. On the 4th day during a rain break, I jumped in the Bronco to go somewhere. Nope, it would fire, cough and try to catch, but it was firing rough just as before. Crap. And a long way from home or a full tool set. We swapped a battery from my friend's truck and I finally got it to catch. Ran rough, but ran. Several minutes later it smoothed out and all was well. For sanity and testing, I put my battery in his truck - his started fine - ugh... Decided it was not the battery, but a mystery. Drove it from time to time the rest of the week and then back home with no issues.
On the way home, I had plenty of drive time to consider this mystery. Condition wise, what was the same between these events? Then I thought - rain. The first time, it had rained for a week at home. Once back and settled, I grabbed a good light and a good pair of glasses - BINGO! Hard to see, but check the center post at approx 9 o-clock.
Darn cheap auto store cap lasted 60,000 miles. Well, it still works - mainly on good weather days. Reminds me of Toby - "I ain't as good as I once was, but I'm as good once as I ever was."