2004 S60 2.4 101,000 miles and sometimes the car will not start after sitting a few hours, it never happens in the morning after the car has been sitting all night, but it has happened at the parking lot at my work twice, first time it did not start after first few cranks, second attempt started normally, tonight after sitting for 3 hours at my work, it cranked for about 8 seconds before it finally sputtered to life. Car drives perfectly fine once running with no issues at all, no CEL or any lights.

Read a few things about installing a universal check valve, cannot find anything anywhere as to a guide on how to do it on these cars, it has a steel fuel tank, I cannot find the fuel filter for the life of me so I assume its one of the models that doesn't have one.

So in that case, would anyone happen to know how I would install a universal check valve? what size is the fuel line? which fuel line would I install it on, could I install it right before the fuel rail? or do I have to do it at the back of the car by the tank?

I don't feel like shelling out the 300$ for a replacement because they were stupid enough to design the check valve into the fuel pump unit.

So please, someone help me on this one??