It really seems like pinpointing the system that has a problem should be easy.

When an engine stalls and won't restart my approach as a tech is usually fairly simple. Remove fuel pump fuse, open throttle, crank engine for 15-20 seconds. At 60-90 deg. F temp this will dry the plugs. Then spray a touch of starting fluid into the intake. If the problem is fuel related the engine will start and stall. If the engine doesn't start I check spark.

Checking spark involves placing an ST125 or similar in the coil wire in series. If you get a bunch of regular sparks then we move on to testing at the plugs. I check multiple plugs because I too have seen way too many of the L31 cap/rotors that fail (due to moisture, and there is a partial cure). If plenty of spark but the engine tries to fire at the wrong time I pull the cap, grab the rotor, and give it a good twist. If it turns the distributor is junk and needs replacement. This happens more often than it should.

If spark and fuel are good then I move on to checking sensor values, plug condition, and engine compression. These engines are fairly reliable and usually the first two tests are enough.




I agree that the distributors and caps for these engines are notorious for problems. The pressed steel rotor "plate" will loosen on the distributor shaft and cause misfires.