I have rebuilt the engine in My boat, however the engine runs perfectly at idle and will rev up to redline when out of gear, but when you put the boat in gear and put a load on it WOT it will not even get past 2900 rpm. The engine has all new fuel pumps ,filter, hoses, distributor, manifolds, Volvo penta SX drive checked out with no issues. new oil in drive. There is one very strange thing with this engine, and that is that even though i replaced the thermostat it seems to be running too cool around 120 Degrees F. This engine uses the ford 5.0 Fuel injected engine, and perhaps there is some faulty sensor, but i put a scan tool on it and it did not give any codes at all. The same prop is being used, and the prop is in good condition. I understand that this engine has a SLOW circuit. Would this have an effect on the engine while under Load? Can anyone out there please help me with some direction as to the cause? I have spent months working on the boat, and i have called several volvo penta service facilities to get some information but due to the age, and the limited production of this particular engine nobody has had much experience with it.
