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Mercury 80hp Stalls and locks in reverse

T

TRColT

New member
Hi
I have a Mercury 80Hp Thunderbolt (1978 or 1979)
Everything runs great when I shift to foward, but I can't get it to reverse without killing and locking the engine.
When I put it in reverse, the propeller start to spin a little then the engine dies. The shift cable can't move anymore (foward or neutral) It is stuck there. The engine won't crank with the starter either. I need to go to the propeller and spin it by hand until it makes a "clic" and get back to neutral.

When I try it on the trailer with the muff, it shifts easily foward and reverse. When I get the boat to the water, the problem happen.
I've dropped the lower unit and spins the input shaft by hand while moving the shift arm. Once again, everything is fine on foward and reverse.


​
If I put the fast idle lever up to about 1200 RPM, I can shift it to reverse without killing it, but it's way to high for a smooth engagement.

Anyone ever encounter this problem?

Thanks ​
 
Last edited:
Today I spent another 2 hours trying to play with adjustement on the shifter cable. I don't think it changes anything. It doesn't get better or worst.

I noticed something when I move the slider with the cable shifter removed. Before engaging to reverse, it's like i'm pushing on a spring. I don't get this feeling when sliding to foward. It might be normal...
 
That's normal. Are you sure there's nothing wrapped around the prop shaft (where you can't see it with the prop in place)??

Jeff
 
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