There are other factors to consider as well. When an engine won't turn at full rpm but the load seems normal, fuel filters could be clogged — the engine simply can't get enough fuel to make full power. But not definitively so. "If the electronic control module senses it doesn't have enough turbo boost, it tells the engine not to add more fuel," limiting both rpm and load, said Charlie Schloemer, president of Palm Beach Power in West Palm Beach. Low fuel pressure and elevated fuel temperature are good indicators of clogged secondary fuel filters. Most electronic engines also display turbo boost. Electronic engine displays can help diagnose problems, even over the phone, Schloemer said, "but you have to know what those readings should be when the boat is running well."