The worst problems I face always seem to be electrical. Most of them are small and easy to fix, but extremely annoying when they occur. I have always had a bit of ignition trouble due to a bit of wobble in the distributor playing games with the dwell, but for the most part the igntion just worked, provided I kept up with points adjustment. One month it didn't.
On the way to work one morning I started having massive running issues. I kept stalling off idle and barely kept it moving down the road if I managed to get started without killing the engine. This really shouldn't happen with the straight six unless something is very wrong. Or fourth gear gets the clutch dropped. It was sputtering and backfiring and the exhaust backfire even managed to blow a large hole in the middle of my very rusty muffler. Needless to say I was having a bad morning. Things weren't much better after work when I couldn't make it up a small incline and out of my parking space after checking timing, dwell, fuel system, replacing points with the spare set along with the condensor and pondering the dirty spark plugs with a blank stare. I got a ride home and made arrangements to tow it.
The next day before towing I started it and drove it around like nothing was wrong. Of course I had a meter with me then, but with nothing wrong I was out of luck. I wouldn't be finding the problem for several weeks yet. A couple of weeks later was a nice humid day in Colorado. My Land Cruiser limped on the way to work again. This time I was ready and had what I needed to figure out the problem. Everything checked out perfectly. Voltage was behaving as it should and every connection and switch was acting properly. Of course I still had running problems.
At this point I had checked out the entire ignition system except that one random accessory I basically forgot I had. The tachometer. Several years of not being able to predict the weather and a tendency to forget even the bikini top at home had taken a toll on the poor little gauge. Now was its time for revenge. After unplugging a few wires the old F fired right up and ran great. Hooking the tach back up knocked her right back down. Well, at least I found the problem. Looking back I remembered it being a little humid (raining two days before) the last time this had happened. Now even changes in humidity were shorting out the tach and effectively bypassing my points. I smacked myself on the forehead a few times for not checking that piece of the system before but then realized how lucky I was to get as far as I did in that condition. I am still looking to get a new tach, but haven't decided what to get yet. This one definately needs to be waterproof. I don't really need it for driving, but it does give me aonther indication of running condition and is nice when using the pto winch to get a solid reference point.