The engine in my 2004 XC70 has started a habit of difficult starting first thing in the morning, and after sitting for several hours.

I would crank the engine over, it will attempt to start, run very rough for a couple seconds, then stall. Sometimes, it will run rough, then suddenly run fine.

About a week and a half ago, I replaced the fuel filter with a Volvo filter. It was after the filter change this starting/stalling behavior started.

My immediate thought was fuel line pressure dropping below minimums when the car sat for several hours. Upon starting, the fuel pressure would slowly increase to operating range, and the car would run fine. I checked the fittings around the fuel filter and Shraeder valve for evidence of leakage, and found none. Also, I do not smell any gas in the fuel filter area.

The only other places I can think of where fuel pressure could be bleed off would be the check valve in the fuel pump (one of my old 740's had this problem), or one of the fuel injectors. The fuel pump is upstream from the filter, so any possible crude that may have gotten into the line should not impact the pump. As for the injectors, I was careful to not get any crude into the fuel line, although one never knows. (BTW, I really like the quick connectors on the fuel filter. So much easier than breaking free rusted bolts and fittings on my old 740's. I live in upstate NY where the roads are bathed in salt all winter.)

The coincidence of this problem occuring right after the fuel filter change has me wondering. Any thoughts from those out there as to what could be the cause of this glitch?

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Gary D