Re: Don't know if I have 10HP or 6HP
Sounds like you need a carburetor rebuild and/or a new fuel pump. Try squeezing the bulb in the fuel line, while running it. If it wants to run then, the pump may be your problem. Also be sure that the vent in your tank is open.
If you bought the motor last year and didn't replace the water pump impeller then, I would do it now. Its not hard, but be aware that the link that allows separation of the upper and lower shift rods, is inside of the lower portion of the midsection, right where the gearcase is bolted on. There is no removable plate to get at it, so you have to remove the four bolts that hold the gearcase on and then drop it a bit. You won't have much room to work (about 1/2" or less), but you will see the brass link, once the gearcase and midsection are separated slightly. Shifting the motor into reverse also gives you a little more room. There are two screws/bolts in the link (both have a hex head a screwdriver slot) and I recommend removing the lower one.
There is a roll-pin in the top of the driveshaft and a slot in a portion of the upper exhaust housing, so you may have to rotate the driveshaft a little, in order to line the roll pin and the slot up. This pin will have to come out in order to remove the impeller but be sure to replace it, as it holds a seal assembly in place, once the motor is put back together. You will not see the seal assembly, because it is held in place in the upper end of the midsection. Without the roll-pin, however, it is not compressed to the point of creating the needed seal.
Be aware also, that there are two different water pump impeller diameters, depending on which pump housing you have. The older aluminum housings have one size and the newer, plastic housings (stainless cup inside) have a much smaller impeller.
Another thing to check, is the thermostat. It is located on the top of the cylinderhead, inside of the triangular housing that has three bolts holding the top on. The cooling system in your motor is designed with a bypass circuit (see the vertical tube running down the back of the cylinderhead), so you will still get water flow out the back of the midsection, even if the t-stat is not opening up. For this reason, its important to make sure that the t-stat is actually opening at the correct water temperature.
BTW, a second look at your motor suggests to me that it is a Johnson, with an Evinrude transom bracket. I say that, because I can see some blue paint on the transom bracket, while the rest of the motor is Forest Green. Both the paint color and the hood latch in the back of the lower cowl, suggest a '68 or '69 Johnson 6hp. I'm inclined to think it is a '68, because it has a rivit plate type badge on the front of the hood, rather than the plastic badge that the '69s have.
Don't worry about the 10hp Erude v. the 35hp thing - some of us have waaaaaay too much time on our hands and can spot these things easily, because we fiddle with them all of the time. I happen to own a pair of '58 Bigtwins and three 6hp motors like yours, so all of this trivia info is just the result of fooling with both over the years.
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