"Mixture is 50/1.
To repeat
"Mixture is 50/1.
To repeat myself, if you indeed have the proper compression and spark on all cylinders, ihncluding that bottom cylinder (#3), I'm still at the bottom carburetor or the reed plate. To inspect the reed plate properly, it would be necessary to remove the intake manifold.
Is fuel actually entering that bottom carburetor. Remove the drain plug on the bottom front portion of the float chamber for confirmation. When you stuck two fingers into that carburetor throat, you should have felt fuel being drawn up thru the high speed venturi.
I've reread everything here but see no mention of the model number of that engine. What is it? The 1983 70/75hp models do not have any adjustable needle valves and your mention of adjusting a needle makes me wonder exactly what engine that might be.
It escapes me which cylinder operates the fuel pump on that engine. Check to see if the pressure line/fitting/surface might be faulty.
Should those carburetors have adjustable needle valves at the top front portion of the uppper body, adjust as follows.
(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.
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