Re: 76 40hp Evinrude wont stay running
If you haven't already, clean the carburetor thoroughly, and manually clean the high speed jet that is located in the bottom center portion of the float chamber with a piece of single strand steel wire.
If any of the carb gaskets are questionable, replace thm.
Depending on which type fuel pump you might have........
(Fuel Pump Diaphragm Test)
(Two Hose Type Only)
(J. Reeves)
Note: This pertains only to the regular Two Hose type fuel pumps.
Leave the hoses attached to the fuel pump. Remove only the two screws that attach the fuel pump to the powerhead. Re-insert those two screws and install a nut to each of them so that the fuel pump is securely clamped together. With the fuel line attached to the engine, pump the primer bulb while observing the pressure/vacuum operating hole on the back side of the fuel pump. Should any fuel leak out that hole, the diaphragm is faulty.
If the diaphragm is faulty, the fuel pump will require rebuilding or replacing. Note that repair kits are not available for all fuel pumps, in which case replacing the pump would be necessary.
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(Fuel Pump Diaphragm Test)
(Three Hose Type Only)
(J. Reeves)
Note: This pertains only to the regular Three Hose type fuel pumps.
Remove only the pressure/vacuum hose that leads from the fuel pump to the crankcase. Leave the other hoses attached. With the fuel line attached to the engine, pump the primer bulb while observing the pump pressure/vacuum fitting that you just removed the hose from. Should any fuel leak out that fitting, the diaphragm is faulty.
NOTE: If the carburetor is obviously flooding, clamp the hose shut that leads to the carburetor.
If the diaphragm is faulty, the fuel pump will require rebuilding or replacing. Note that repair kits are not available for all fuel pumps, in which case replacing the pump would be necessary.
(Carburetor Float Setting)
(J. Reeves)
With the carburetor body held upside down, the float being viewed from the side, adjust the float so that the free end of the float (the end opposite the hinge pin) is ever so slightly higher (just ever so slightly off level) than the other end. And when viewed from the end, make sure it is not cocked.
(Carburetor Adjustment - Single S/S Adjustable Needle Valve)
(J. Reeves)
Initial setting is: Slow speed = seat gently, then open 1-1/2 turns.
Start engine and set the rpms to where it just stays running. In segments of 1/8 turns, start to turn the S/S needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running.
Eventually you'll hit the point where the engine wants to die out or it will spit back (sounds like a mild backfire). At that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.
Note 1: As a final double check setting of the slow speed valve(s), if the engine has more than one carburetor, do not attempt to gradually adjust all of the valves/carburetors at the same time. Do one at a time until you hit the above response (die out or spit back), then go on to the next valve/carburetor. It may be necessary to back out "all" of the slow speed adjustable needle valves 1/8 turn before doing this final adjustment due to the fact that one of the valves might be initially set ever so slightly lean.
Note 2: If the engine should be a three (3) cylinder engine with three (3) carburetors, start the adjustment sequence with the center carburetor.
When you have finished the above adjustment, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.
. It stayed runnin and stopped and started up without a hitch, just have to get my throttle controls fixed now, havin problems with it now.