"I have a 7.4GL volvo penta, 4
"I have a 7.4GL volvo penta, 4-bbl holly carb. W/DP-E179 drive unit in a 24' pursuit denali 1996 that I just bought. A volvo certifed mechanic has replaced cap, rotor,wires,props outer bearing in outdrive,water pump,adjusted timing,rebuilt carb,pulled and checked disterbtor checked compression,checked fuel pump,after all of this the boat ran the same. It runs good at high speed 3000rpm or more. but has vibration at lower speeds the fuel pump does make a whining noise at low speed ,mechanic said that was ok.3-plugs fowl out after about 5hrs running time this could be leaking seals on valves but why would the engine not run smooth when the plugs are just put in new and It runs great at high speeds for a few hours.my next step is to have the heads rebuilt and exhaust manifolds checked out. does anyone have other ideas my check is running short. thanks tom"
"I have a 7.4GL volvo penta, 4-bbl holly carb. W/DP-E179 drive unit in a 24' pursuit denali 1996 that I just bought. A volvo certifed mechanic has replaced cap, rotor,wires,props outer bearing in outdrive,water pump,adjusted timing,rebuilt carb,pulled and checked disterbtor checked compression,checked fuel pump,after all of this the boat ran the same. It runs good at high speed 3000rpm or more. but has vibration at lower speeds the fuel pump does make a whining noise at low speed ,mechanic said that was ok.3-plugs fowl out after about 5hrs running time this could be leaking seals on valves but why would the engine not run smooth when the plugs are just put in new and It runs great at high speeds for a few hours.my next step is to have the heads rebuilt and exhaust manifolds checked out. does anyone have other ideas my check is running short. thanks tom"