I changed the filter on our TR97 with the 7.5L and ever since have had nothing but trouble with air. You have to prime it each time you shut 'er down and restart, will run just fine otherwise. There is an air bubble in whatever the plastic bulb is under the lift/supply pump on occasion. I cracked the line just before the injection pump several times and got air out and did the same at the bleader on the filter housing. The only difference is a new filter which is a Napa and is some sorta improved reverse flow deal. So where would the air be coming from?