I have a coleman 7956a856 that I was trying to light (the pilot). There is air being pulled through the unit around the pilot. This keeps extinguishing the pilot flame and makes it difficult to re-light. What is causing this suction of air up into the exhaust pipe?

High wind conditions across the roof will create those conditions. It is also possible the pilot orifice is partially restricted not allowing enough gas to come out of the pilot causing a small pilot flame which in turn would extinguish easily.

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