Sand and rocks in 92 XP, help?

[tmskislc]

Near the end of last season, my girlfriend started up my 92 XP Sea Doo on the shore and sucked a bunch of small rocks and sand into the machine. After, the machine would run fine for about 2 minutes and then stop running. It would not start again. If you let it sit for a few minutes it would start back up and run again for a few minutes and then stop. I paid to have a tech look at the machine and he stated that the impeller had been damaged and that he had corrected it to where he thought it work fine. He felt that the machine was not getting the proper water due to the damaged impeller and was overheating and stopping. He also flushed the engine and stated that there was a lot of sand in the engine. I looked at the impeller and it looks good to me (no big dents or knicks). Today, I tried the waverunner out and nothing has changed. It will run fine for a few minutes and then die. What would be the next step in trying to solve the problem? I was thinking about pulling off the head and seeing if there is sand buildup in the machine, but I am not too familar with the way the engine works. Does the water go through all areas of the engine or just the top head part of the engine? In other words, is pulling the head to clean out the sand a waste of time because the entire engine would need to be taken apart to get the debris out. I am figuring there is somekind of blockage somewhere. Any help would be greatly appreciated.