Re: 91 johnson 40hp out board motor
If the engine stopped due to overheating, the engine would be seized, and it would be impossible to crank it over until it cooled off somewhat.<br /><br />You should have a warning horn that beeps momentarily when you turn the ignition key to the ON position. If it does, then I would assume that the warning system is operational. In which case, if the engine overheated, the warning horn would sound off steady before the engine was hot enough to do any damage.<br /><br />Also, if the engine got that hot, the paint would be discolored and any wire in close proximity to the powerhead would be melted.<br /><br />When the engine stopped running, was the fuel primer bulb flat? If so, I would suspect a fuel restriction between the primer bulb and the fuel supply. If you're using portable tanks, make sure the vent is open if it exists.<br /><br />If you have a built in tank, see the following and use the info that would apply to your engine:<br /><br />(Fuel Anti Siphon Valve)<br />(J. Reeves)<br /> <br />Many of the later OMC V/6 engines incorporate a fuel restriction warning via a vaccum device attached to the powerhead. If the engine overheats, or if you have a fuel restriction, the warning is the same.... a steady constant beep.<br /> <br />NOTE... Only the V/6 & V/8 engines have the above "Fuel Restriction Warning". The warning horn will not sound on the other models. <br /><br />The fact that a engine is not overheating, but the warning horn sounds off with a constant steady beep, and that the rpms drop drastically would indicate that the engine is starving for fuel due to a fuel restriction. Check the built in fuel tank where the rubber fuel line attaches to the tank fitting. That fitting is in all probability a "Anti Siphon" valve which is notorious for sticking in a semi closed position. It will be aluminum, about 2" long, and the insides of it will consist of a spring, a ball, and a ball seat. If this valve exists, remove it, knock out those inner components which will convert it to a straight through fitting, then re-install it. Hopefully that cures the problem.
