BOAT ENGINE (MerCruiser GM 305) PROBLEMS!?
Hi, I have a 1983 MerCruiser GM 305 marine engine. The engine wont run right and boat wont even plane out. It was running not great but would plane out and get up to 3100 RPM, then I checked timing with a timing light and it was jumping from 8 BTC to 10 ATC.
So now I got a boat that will get up to 1500 RPM in water. It will run at 4500 RPM in nutral but back fire through carb. Also wont open 4 barrel when in water trying to plane.The carb is a Rochester Q-jet 4 barrel . I have NO POWER
Here is all I did, I rebuilt Carb, new points, new condenser, Cleaned/checked advancing springs, new plugs, new wires, new filters(gas,oil,water separator), belts, did compression check(155psi is all), new timing chain and new distributor cap. On my manifold is says it should run at 4400-4600 RPM in water at WOT and I have only seen it run like that when I first bought it 3 years ago and that only lasted a month or so. I don't want to have to rebuild engine as I just rebuilt one for my race boat. Also the boat runs great at idle. I don't think it is the cam, or timing chain as it was running OK while running at the top 3100 I got out of it a few days ago. I want it back to the 4500 RPM it is suppose to be. I need this running soon as this is my charter boat.
Thank you
Hi, I have a 1983 MerCruiser GM 305 marine engine. The engine wont run right and boat wont even plane out. It was running not great but would plane out and get up to 3100 RPM, then I checked timing with a timing light and it was jumping from 8 BTC to 10 ATC.
So now I got a boat that will get up to 1500 RPM in water. It will run at 4500 RPM in nutral but back fire through carb. Also wont open 4 barrel when in water trying to plane.The carb is a Rochester Q-jet 4 barrel . I have NO POWER
Here is all I did, I rebuilt Carb, new points, new condenser, Cleaned/checked advancing springs, new plugs, new wires, new filters(gas,oil,water separator), belts, did compression check(155psi is all), new timing chain and new distributor cap. On my manifold is says it should run at 4400-4600 RPM in water at WOT and I have only seen it run like that when I first bought it 3 years ago and that only lasted a month or so. I don't want to have to rebuild engine as I just rebuilt one for my race boat. Also the boat runs great at idle. I don't think it is the cam, or timing chain as it was running OK while running at the top 3100 I got out of it a few days ago. I want it back to the 4500 RPM it is suppose to be. I need this running soon as this is my charter boat.
Thank you