1/4 cup in 10 full, timed with a clock, seconds, sounds low. 6V system or 12V system, makes no difference. Your test is good, it is real life condition. Simulating trying to start a motor that may have no gas in the carb bowl. Starts immediately? Then dies. Does it die immediately? Like real fast? That there is electrics. The ignition switch or foot switch or if you had a ballast system, it would be that. After it dies, check the throat of carb for squirt. Run a gravity gas feed into carb inlet without blowing yourself up. Seems odd there would be just enough gas in bowl for one squirt start and nothing left to run a minute. I'm going with electrics until you try some stuff. Check the linkage too.....and choke.
Erratic spurts is one thing.....it will pulse but be a evenly spaced steady pulse, and strong if battery is good. After lines are full, maybe one pulse per second. Try 15 clock seconds and see how much gas you get. The cam shaft is only running at half speed of the crank, so 10 seconds is short. On the other hand 1/4 cup will fill a carb bowl. So OK, I talked myself back to electrics/spark.
BOTTOM LINE: Your truck won't stay running, right? We should start there with normal trouble shooting. Gas/spark/air/compression.
I don't know what motor or ignition system we are talking about. Would be nice to know that. What key switch? solenoid or foot start? Must be 6V???? Must be 39 or 47?????? You have no right to remain silent, nothing you say will be held against you.
