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mercruiser 470 sterndrive troubles

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vernelyon

New member
I have a late '70s boat with a mercruiser 470 i/o. When hooked to water boot in yard in runs and shifts well. In the lake, after about 15 minutes running at slow to medium speed the engine begins to die. It is hard to shift into nuetral. Once in nuetral it starts right up but shifting it into forward or reverse causes it to die. I checked the lub in the outer drive unit and it is full. Propeller turns freely. Outer unit raises and lowers without problems. There doesn't seem to be any problems with the shift cable. Engine will run at any rpm while in nuetral. This is driving me nuts. Any advice from anyone will help.

Verne
 
It sounds like the problem is originating with the interupt switch. If you trace back your shifter cable to the spot where the front and rear cables connect, you will find a micro-switch that momentary shorts out the ignition to make it easier to shift out of gear. It is only meant to make the motor hestitate for a second but if switch is defective or out of adjustment it can kill the motor completely when attempting to shift gears.
 
Thanks for the tip. I checked out the momentary switch and it operates correctly. I'm thinking that maybe the problem lies with the fuel system. I installed an inline fuel/water filter last year but left the check valve in the fuel tank outlet fitting. Perhaps with the boats forward movement some debris is temporarily clogging the check valve. Sitting in my yard with a water muff it runs great but its not going anywhere. I've checked the linkage and everything seems to operate smoothly.
 
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