Re: 1998 Evinrude 50 SP "Runability Problem"
The 1998 50hp Evinrude was manufactured a few years after I retired. However, in reply to your email request.......<br /><br />Remove the spark plugs and double check the compression. While doing so, check closely for water traces on the spark plugs which might actually be water or what appears to be very small round objects more or less welded to the electrodes and porcelain.<br /><br />Are the spark plugs the correct plugs, and are they gapped properly?<br /><br />With the s/plugs still removed, rig up a spark tester whereas you can set a 7/16" gap.<br /><br />At the starter solenoid, use a jumper arrangement to connect from the battery side of the starter solenoid to the 3/8" nut that engages the solenoid (not the 3/8" ground nut). A automotive push button type jumper is prefered for safety, but even a small jumper wire will suffice.<br /><br />Have the ignition key in the ON position and crank the engine via the jumper arrangement. The spark should jump that 7/16" gap with a strong blue lightning like flame.... a real SNAP!<br /><br />Disconnect the throttle cable from the engine so that you can move the throttle linkage at the engine by hand from the idle position to full throttle/full spark advance position.<br /><br />Crank the engine and while slowly moving the throttle linkage from idle to full throttle, observe the spark. It should stay exactly the same..... strong blue etc etc. If moving the throttle affects the quality of the spark, that should lead you in the area of the problem.<br /><br />If when checking the spark,even at a idle, you find that it is weak, erratic, orange looking, disconnect the large RED electrical connector at the engine, then check the spark again. If you now have good spark, the problem is usually a intermitenmt shorting ignition switch, in which case, replace the switch.<br /><br />If originally the spark was weak, and even disconnecting the large RED electrical plug resulted in no improvement, the most logical suspected component would be the stator/charge coil assy (under the flywheel) that provides approximately 300 AC volts (beginning of the ignition system) to the powerpack. If that stator/charge coil is failing, melting down, whatever, then obviously there is no way that the ignition can perform normally.<br /><br />Keep in mind that advice is helpful if it is followed. Jump over something as in the term "short cut" and the advice is useless. You may not fall into this catagory but it's something worth mentioning.<br /><br />Note.... If all is okay in the spark department, I'd suggest that you remove and double check the carburetors. Remove and manually clean all fixed jets, run solid wire thru all passageways/tubes etc. If the slow speed jet is adjustable, the following may be of some interest.<br /><br />(Carburetor Adjustment - Single S/S Adjustable Needle Valve)<br />(J. Reeves)<br /><br />Initial setting is: Slow speed = seat gently, then open 1-1/2 turns.<br /> <br />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.<br /> <br />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. <br /> <br />Note: 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.<br /><br />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.<br /><br />So..... What are you going to do with the rest of the day?
