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1973 Mercury 2 stroke stalls when put in gear

H

Hakrak

New member
Hi all, I am having some issues with my 1973 mercury two stroke when I put it in gear and try to drive it slow. It does not stall if I shift it quickly to full throttle and ease it a bit works fine. It just seems to stall when I shift it into gear with no throttle and minimum speed. It idles fine. Any idea why this happens?
 
Do you mean the idle mixture screw? I did adjust it to about two turns out so it does idle fine when in neutral. If o open it more it will bog down when idling
 
Have a tach? Idle speed in the water, boat moving in F gear should be around 675 set by your throttle linkage knurled idle set screw on one of the arms (the arm) connected to remote throttle linkage inside the engine. Fast enough to take going into gear but slow enough to engage with out a "clunking" of the drive train. If you have that and there is nothing actually wrong with your engine your idle mixture screw is used to prevent what you are experiencing. It is only opened enough for you to hammer down on the throttle from the above condition and the engine take the throttle, put the boat on plane, and not hesitate.

If you do/try to do that and it fails, you need to start cleaning up your fuel system starting with cleaning your carbs and installing new kits, a new fuel pump kit wouldn't hurt as the diaphragm gets stiff with age and doesn't pump like new, maybe a new fuel filter (cut the old one open and if black dots or crystalline tan particles do what I suggest next. Swab out a couple of your internal fuel lines and if little black flakes inside, replace the lines; a new bulb and fuel line to the tank probably wouldn't Hurt..........all just little things that should be done over the years that you may not have known needed to be done.
 
Thank you for your reply, unfortunately I do not have a tachometer but the engine was not idling before so I had to remove the carb and apart out the passages. Now it does idle fine and the idle screw seems to be set accordingly about two turns out as if if move it either direction starts to run rough. I realize that the cold start lever does not connect to the throttle but seems more like it’s a spark advancer that goes under the flywheel to adjust the rpm’s. If I lift that cold start lever slightly to increase the rpm and then shift into gear it does engage but with the clunking noise
 
The fuel pump might have been messed up as I was getting air into the fuel line for some time and now it seems like there is no vaccume and I have to pump manually. Not sure how that could affect what I am seeing tho
 
What motor , a 4 HP or 115 HP ?---The fuel pump runs with crankcase PRESSURE pulses.----Perhaps throttle plate opens too early.----That will stall your motor every time.
 
40hp the throttle plate to me looks like it opens to late but I don’t know much about boats. Looks like it’s starts opening when the leaver is almost horizontal
 
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