I have replaced my alternator but when I pull the negative connector off of the battery the engine shuts off. Could there be another problem than the alternator?

Your alternator is not made to continue running the vehicle - during an absence of battery voltage and amperage. That's a crazy thing people do - remove the battery cable to see if the charging system is working. There is so much wrong with that hypothesis of testing. Have you checked the state of charge of battery - and its ability to sustain a load and charge? That's the first stop. Battery voltage and amperage has much more to do with the concern than the charging system does. That's secondary - and maybe problematic also but - you must start at the beginning. Seek guidance at a local shop near you. https://repairpal.com/auto-repair-near-me Click the link or call us at 877-913-1554. We'll gladly find you a certified RepairPal shop in your area.