You can expect a little more pain at the pump over the holiday weekend, with the price of gas going up this month. The price of diesel and kerosene, however, went down again.With effect May 16, the Finance Ministry says the maximum price of petroleum products change is as follows: Gas +1.9 cents a litre; diesel -2.7 cents a litre, kerosene -5 cents a litre.As a consequence, the Ministry says the maximum retail prices displayed at the pumps are:Gas just over $2.12 a litre; diesel $1.86 a litre, kerosene; $1.55 a litre.Last month the price of gas went down 4.8 cents from March, hitting $2.10 per litre, some ten cents a litre lower than it was one year ago.