When I first bought my Land Cruiser I could barely limp it home. Whenever I gave it more than half throttle and caused the secondary to open up on the two barrel carburetor, the engine would flood and I would slow down and usually backfire. After replacing all the usual ignition components--plugs, wires, cap, rotor & points--I decided it was time for a carburetor rebuild. Once I got the rebuild kit I pulled it off the engine and started to take it apart. This all went fine and I started to realize why the engine was being flooded whenever I gave it any gas. The secondary jet was nearly twice as large as the replacement jet! I was at the same elevation as the previous owner, so the reason was just a very long time between rebuilds. I finished putting it all back together and was amazed at the power i was getting from the old beast. However, things were still not all where they should have been.
I still had serious idle problems and the occasional backfire, so the troubleshooting began. After checking to make sure that I hadn't missed anything with the carburetor installation I figured I should check all the vacuum connections. The carburetor connections and distributor connections were ok, but the brake booster line had a large enough crack I could stick my little finger through it. The idling problems soon cleared up and I was on my way to the next little problem.
Well, on the way home from work one day my FJ40 suddenly backfired and died. I tried getting her started back up, but to no avail. When I got her towed home (I was only a mile away) and into the garage I found the source of the problem. When I had replaced the condenser on the side of the distributor, I had apparently not tightened the nut holding it enough and it was loose. Once I got that tightened back up everything worked just fine.