no power in forward gear

[Kalvyn]

I have a 69 merc 650 65 hp thunderbolt. My motor runs great when i have it hooked up with a hose and adaptor but when i put the boat in a body of water it idles high and when i try to retard the distributor to the idle stop screw it kills the motor. As i'm trying to back off the throttle and rpms drop while still in neutral the motor kicks. I can get it into forward gear but when i throttle up the boat gets to 6 mph and stays there. When i switch to reverse i have plenty of power. I have nit picked this motor and still can't figure it out. I have checked spark(replaced distributor wires too), carbs, and timing. Still no luck. All checks well. Motor fires up like a champ. Timing advances with throttle, carbs open up????There is one weird thing though, is that my Seloc Manual calls out my motor to have a type three ignition. All the components signify type two but there is one wire that is characteristic to a type three. It's hard to explain but look at both diagrams if you have a manual (in the back of book) and it is a brown wire that comes from the harness to the fuse box on the second terminal down. It leads to the box and is a tachometer hook up????? Don't know if i should unhook or not. If anybody can help it would be greatly appreciated.
Thanks

 

[CharlieB]

Re: no power in forward gear

Verify spark on each cyl is able to throw a hot blue arc across a 7/16 gap. A bad dist cap or wire leaving a dead cyl will sound and rev fine on the hose but be a dog in the water.

Verify compression on each cyl, same reasoning as above.

Carb idle adjustment, should be perfected while on the water and in Forward gear. This is required for proper mixture requires the exhaust back-pressure of the water in the mid-section and the load of the prop.

Initial adjustment on the hose to best idle speed plus 1/8 turn out should get you close enough to get started on the water.

Repost with your progress.

 

[Kalvyn]

Re: no power in forward gear

Thanks for the advice. Check the spark on all plugs. They were good. And while i was doing that i verified the the firing order and found out that i had #3 and #4 wires switched. Reconnected and took the boat out to test compression cause i was told to run true compression at full throttle. Took it out and it ran great. Haven't had enough time to run it for any good period of time cause the weather but I'm going to this weekend. Just glad it was something fairly simple. Thanks again