I'm thinking it's the fuel pump,I need to know where it is and how to change it
If you are saying the engine starts and runs for 15 seconds and dies and then starts again for another 15 seconds and dies . . . the distributor seems to be doing its job. You might want to check if there is a fuel restriction somewhere (filter or pump).
Fuel pump
The P1684 code simply means that the battery has been disconnected within the last 50 starts.
Caravan Convertible
If if starts bubbling even if the engine is cold, most likely blown head gasket. If only when engine warm, stuck thermostat.
wheels off van raised engine shakes side to side at 40 kmh
if it starts and runs for just a few seconds then dies it is generally a carburetor issue. clean or replace the carb and that should solve your issue.
caravan
It's probably your IAC.
The contour warm air blower starts on a timer 45 seconds after the burner initially starts, not on temparture
Diagnosis: Engine Won't Start or RunCheck related link below
change fuel filter