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    No water from cooling hose.

    1977 50 HP Ran into 1' mudflat and killed motor. Poled out to deeper water and restarted engine but got no water flow from cowling tube. Dropped lower unit at the house and remover water pump. No clogs or issues to be found in pump assembly or lower unit intake screen. Blew compressed air...
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    Lower Unit Ratio Question

    My 1977 50 HP should have a 2/1 ratio as suggested by experts on this forum. I bought a used LU that seems to have around 1.75 to one. My question is.....wouldn't a 1.75 turn the propeller shaft faster than a 2 to 1 Ratio? If I'm getting a full prop rev before I turn the drive shaft twice, then...
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    Lower Unit Issues

    1977 50 Hp Merc 500 Original lower unit destroyer on rock. Replacement is having issues shifting and running. Engine starts and idles fine but when shifting into forward, engine dies repeatedly. After several attempts I can slowly nurse RPM's up until it stopes at about 3/4 throttle. Not enough...
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    50 HP Lower Unit Drive Shaft

    I have a 1977 500 with a busted lower unit housing. I bought a replacement on ebay that has a drive shaft that is 3" shorter than the one I have. Looks like my choice is to swap drive shafts. My question is how do you remove the water pump base? There is nothing to grab and it is preventing me...
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    1978 Merc 500 Turning over too slow to start.

    My Merc will spin what seems to me fast enough to start, but it won't. When I hook a battery charger to the battery, the engine spins fast and starts. After running a while, the engine starts easily throughout the day. The Marine Starting Battery is almost new and checks out with a load tester...
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    Mercury 500 Needs more throttle

    When my 1977 Mercury 500 runs at full throttle it seems to me to not be wide open. If I back off my throttle stop screw to get more RPM's, do I need to do anything with timing as well? I used to get 30MPH on my boat but after a trip to a mechanic to help me solve leaking carb issues, I am only...
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    1977 50 HP Loss of Power

    Engine has performed great for years until recently. Became hard to start. I installed carb and fuel pump kits which I have done before. First time on water ran pretty good except hesitation when accelerating. Second time on water ran several miles up and down Tennessee river with no problem...
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    Mercury 500 Needle valve

    My new needle valves are spring loaded and my question is....how do I adjust my float valve with spring needles? I am concerned about distorting springs when attempting to get proper float measurements.
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    Merc 500 Choke Shutter Plate

    Putting my fuel pump integrated carbs back together and totally forgot how the choke shutter plate springs are supposed to fit over shaft. Any videos or pictures available to guide me through this? Many thanks!
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    Run Carbs dry?

    I have read many recommendations from you guys to always run your carbs dry after each use. My question is....I use my 1977 Merc 500 once a week, almost every week. With this kind of usage would you guys still run dry after each use or do I use too frequently for this preventative measure? thanks
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    Ethanol Fuel

    I posted earlier about my 1977 50hp engine being hard to start. Spark good....compression 120 on all cylinders. I have been using an unleaded with 10% ethanol for years. I do not have a convienent source for non-ethanol between me and my fishing holes. I have a friend with a 1973 Evinrude that...
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    Merc 500 Hard to start.

    After several years of great service my 1977 50 HP has been getting harder and harder to start. She is electronic ignition. I am going to start with new spark plugs. What are your recommendations? If that doesn't improve things then i will do the compression test ect. Thanks
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    Durn Mercury made some great engines!

    I have had my 1977 Mercury 500 for four years now. I go fishing at least one a week and sometimes twice. My Merc fires up everytime and runs as long as I want her to. Saturday on the Tennessee River we put on several more miles with her running wide open and never a miss or hesitation of any...
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    15 HP 4 Stroke Loosing Power

    I have a new 4 Stroke purchased this past winter and the last several times out it is stalling at full throttle. It runs fine at 3/4 throttle but when I try to open it up it will surge like a fuel starvation issue in a carburetor engine. This unit was carefully broken in over several fishing...
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    8Hp 4 stroke carb question

    I have an 8HP 4 stroke (Tohatsu i understand) that i have replaced carburetor after years of good performance followed by bad performance and hard starting. I had cleaned carb repeatedly but did not improve starting. The replacement carb does not have the primer bulb spring valve but it does...
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    1977 50 HP Fuel Pump Issue

    I have the carbs with the intragal fuel pumps and my question concerns the fuel pump kits. There are several different diaphrams included with the kits. Which one is the right one for my motor? One is a very thin black rubber and another is a thicker black rubber, and finaly one is a thicker...
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