1987 OMC Cobra Power

Last summer I took the boat ou

Last summer I took the boat out of storage and all summer it didnt have any high end torque. Could barely go on plane...

Any idea what could be the issue?

The summer before it was fine. What could have happened during the winter?

The carb was replaced last year and we tried cleaning the fuel system with some adatives.

Good day Bill
Could you give

Good day Bill
Could you give us some info on the type of craft engine type size and so on.
There is a lot of help here.

Frank

May need information on outdri

May need information on outdrive as well. Last year I had some of the same problems but turned out the outdrive was the cause. In my 88 OMC Cobra.

"Its a 1987 Bayliner 2750 5.7l

"Its a 1987 Bayliner 2750 5.7l 260hp and the outdrive has recently been rebuilt.

But it was fine before the boat went away for the winter. otherwise fires up idles good and smooth, until you put a load on it.

I have been thinking exhaust as the boat was overheating and the flappers melted. I was told by the mechanic that all the pieces are now out as thats what caused the outdrive to go the last time as plastic was melted around the shifter rod.

New plugs cap condenser and rotor all new last year. Coil?

Otherwise how about fuel delivery? carb and filter on the carb was replaced last year. Fuel pump?"

"If you want to pursue the fue

"If you want to pursue the fuel delivery then the easiest way to rule out anything beyond the engine would be to hook up a small portable tank and run from that. There are at least 3 things that could cause a delivery problem, the fuel pickup in the tank could be partially clogged, the anti-syphon valve (usually on top of the tank where the fuel line is attached) could also be partially clogged and the air vent for the tank could be clogged causing too much vacuum in the tank for the pump to overcome. You can do a water test check for the air vent problem. While out running and experiencing the problem just crack the fuel cap open, if you hear swish and the engine picks then the vent is the problem."

I'm assuming the problem b

I'm assuming the problem began after the overheating? What caused the engine to run hot? I would start with a compression check if you haven't done one. You could have more damage from the overheating.
Also assuming the carb was replaced in an attempt to solve the power problem? Is the new carb a direct replacment? Have you checked to see if you are actually opening the throttle fully?

"The Carb is a direct replacem

"The Carb is a direct replacement and I believe the throttle was fully open.... I hope to start working on this as the weather gets warmer, the first thing I want to test is the exhaust is flowing free, any ideas on the best way to test this towards the stern drive? I will remove all the risers see if they are clear and will replace the flappers as they have melted away."

"If the flappers are gone then

"If the flappers are gone then I would remove the drive, chances are you find one or both right in the exhaust tube causing an obstruction."

"That was already done last ye

"That was already done last year, found parts of the flappers in the drive and removed them.... anywhere else parts could hide in the exhaust path???"