Transaction declined while trying to purchase gas

Symptoms

Attempted purchase at a gas pump fails, even though the card is assigned to a pocket with funds. This can happen even if there are enough funds in the pocket to cover the standard cost of a tank of gas. 

Resolution

Please enable Credit Line or ensure that you have over $150 in the pocket your card is pointing to. This will ensure the original authorization is accepted and you are able to continue with your transaction. 

Cause

Likely what has occurred is a result of how merchants like gas stations, hotels, and rental car companies, treat debit card transactions. Such merchants typically reserve a larger amount than the expected cost (say $100 at the gas pump) because they cannot predict how much available funds are in a debit account. By attempting to authorize more than the anticipated cost, the merchant is assured there will be enough funds in the account to cover the end purchase amount.