reverse problem

[Ridethe93gt]

i've got a 1973 IMP Aztec w/ a 302 inboard and a mercruiser 888 outboard.....i just put a new motor in (which i found out was in vain(water in the oil)) but anyways...the boat will shift fine forward-netural-reverse when its not running...but when its running and i try to shift to reverse it kills the motor....and if i leave it in reverse it will turn over but not start.....forward works fine.....what could be the cause of this????? a saftey switch???

thanks in advance for your help,

JJ

[redtech]

cable adjustment

[Ridethe93gt]

i thought that too but i figuard out it was a switch that is triggard when you throw it in reverse...from what im told this switch is suppose to just flip on then right back off to kill the engine while shifting....looking at it i cant figuare out how it would do this....it looks to me like when it shifts it just puts it in the off position and stays there when fully in reverse and there is noway to adjust it to do otherwise.....so i unhooked the switch and tried it and it shifts fine.....no grinding or anything....is it ok to leave it this way or am i about to mess something up??

[redtech]

no not ok to leave it this way the interupe is to allow you to get the drive out of gear you can run into big problem pulling the control lever back to nuetral if left like this
please check the following before boating like this
intermediate cable routing and condition
the cable should not make any sharp bends and move freely

[Poida]

Hi Redtech

How does this work then? Reason for wanting to know is I want to separate my gear lever from my throttle control. As it is now, the lever is all in one.

The setup you are talking of here, it sounds like the gear lever and throttle control are separate, is this true? I can't understand why you would want your engine to cut out when you are changing gears because you wouldn't want to start it again everytime you change gears, bit difficult when docking.

The only thing I can think of is there is a system which will not allow you to change gears if your engine is running to fast, leading to shearing of shafts, gears etc. if you change gears. I was thinking of doing some kind of arrangement like that on my boat when I convert.

Is this what we are talking about here?
I need educating.

Poida

[marshmat]

The switch in question is common to many engines. What it does is to momentarily kill the engine, only for a few milliseconds, as the clutch dog or cone disengages. For a brief moment while the clutch mechanism is moving, its teeth or surfaces are only just on the verge of being engaged, and if a power pulse from the engine coincides with this instant, a bit of metal can be scraped off of the clutch mechanism. So by killing the engine for a few milliseconds as the clutch moves, we can guarantee that no power pulse will coincide with that instant where the mechanism is most vulnerable. Once the clutch has moved, the spark plugs get their power back and the engine keeps on turning. (All of this should happen in less than a couple of revolutions, usually, and so the engine doesn't actually stop turning.)
What we have here appears to be that the momentary-kill switch is jammed, and so does not return to its normal position quickly enough after the shift. I would suggest thoroughly inspecting all throttle/shift connections and cables, then replacing the switch.

[Poida]

Thanks Marshmat, since I have clutch plates, I think then a kill switch would not seem neccessary.

[redtech]

Poida, Marshmat is right in what he said and the merc uses this switch in just about everything from a tr to an alpha drive as far as the shift and throttle gos they are two differant functions inside the same box if you would like to have differant levers just a differant control box will do there are two cables intering your control box now one is shift and the other throttle