Loss of fuel pressure

[jehutyd]

Just trying to get some information hopefully. I have an 06 Suzuki XL7 that I got about 6 months ago. The AC was squealing so I had a shop change the serpentine belt and when I got the car back, it started up fine at the shop squealing went away. Now whenever I go to start the vehicle I have to put the key in and wait 10 seconds for the fuel pump to build pressure and the vehicle to start. It took a bit of internet research to figure out that I think that is what the problem is. Some of the possible causes I am found are fuel pump check valve bleeding fuel pressure back into the tank, a dirty fuel filter that is making it difficult to get fuel through, or a fuel pump that is just starting to go out. Of those three can anybody tell me if any of them would start to show symptoms over time or would it be like it was where one day it was fine, the next it was not working at all? I don't want to blame the shop messing the vehicle until I feel confident it wasn't a coincidence. The vehicle does have over 100k miles so things may go wrong with it. With that said is there anything else that you could think of that could cause the issue, and is there anything in the area of the belts that could cause the issue that the shop may have messed up? I will outline specifically how it is below.

1) If I put the key in and just turn it all the way to start it will turn over and not actually start. After 2-3 tries of putting it all the way to start it finally will.
2) If I put the key in and move it to on and just let it sit for about 10 seconds it will start right up.
3) If I turn the vehicle off for less than 5 minutes it starts right back up if I just put the key in and go all the way to start. Anything longer then that and I need to wait about 10 seconds at the "on" position before moving it to the "start" position.
4) I did notice driving it around that it is idling a bit rougher then before. When it is actually driving though the engine feels smoother.

Thank you everybody for your time and opinions and help.

[DeltaP]

Try turning the key to "on" for 5 seconds and then off, do not start. Do this several times in a row without starting. Then turn the key to "start" and hold it there till it starts. If it starts you have a fuel pressure problem. Change the fuel filter then if no positive results check the fuel pressure and compare to OEM specifications.