Having read hundreds of forum posts on Volvo Penta Fuel Cell failures, it seemed that the primary approach was to test the pump (Thanks Don) and then spend $750 to replace the unit, hoping that it wouldn't crap out again next year. Here's my story on how I fixed my fuel cell.
I have a 2000 Regal 2150 with a Volvo Penta 5.0GIPEFS. At times under load, the engine would crap out, but never die. After testing the system per Don's instructions, I discovered that when the engine was craping out, the fuel pressure was dropping from 30psi down to as low as 10psi. With everything pointing to a bad fuel cell, I decided I had nothing to lose by taking it apart.
The fuel cell only has a few screws and then it pulls apart. I discovered several problems. First, as has been reported elsewhere, the paint inside the fuel cell was peeling. This caused the screens on both pumps to plugs. After blasting the two screens clean, I discovered that the low pressure relief value was blocked open by what looked like a metal shaving. I think, but can not confirm, that between the pump screens being plugged and the low pressure valve being blocked open, the high pressure pump was starving for fuel.
After cleaning everything out, I put it back together and took the boat out. After buring through 10-gallons of fuel at 55mph, I still had perfect fuel pressure and no problems. My advice to anyone with Volvo Penta Fuel Cell problems, you have nothing to lose by taking apart a faulty fuel cell to clean it. Worst case, you still have to buy a new one.
PLEASE BE WARNED: There is a ton of gas inside of this fuel cell. Be prepared to dispose of the gas and try not to blow yourself up when doing it in your garage. While this was easy for me, I was at one time an ASE certified mechanic, so it may not be so easy for you.
Here is one more picture of the corrosion inside of the fuel cell:
P.S. Shame on Volvo Penta for designing such a terrible fuel cell and not making parts available to repair it!